, J 6: dantur per iptam naluram
intellect
in.
Windelband - History of Philosophy
But in addition to sensation, perception has also the feeling-element of pleasure and pain, and out of this, in connection with the move ment of ideas, develop desire, love and hate, hope, fear,1 and — as the result of all such changes of the practical consciousness —
finally, the moral will. So knowledge and morality grow upon the soil of the sensibility.
This systematic construction had great success. The systematic impulse, which was repressed in the metaphysical field (cf. § 34, 7), threw itself with all the greater energy upon this "analyst* of the hnman mind" as a substitute; and as Condillac himself had already woven many acute observations into his exposition of the develop ment process, so a whole throng of adherents found opportunity to take part in the completion of this stiucture by slight changes and sin[tings of the phases, by innovations in nomenclature and by more or less valuable deductions. The Government of the . Revolu tion recognised as philosophy only this study of the empirical development of intelligence, and Destutt de Tracy gave it later the name "Ideology. ''1 So it came about that at the beginning of our century philosophers were in France usually called ideologists.
7. With reference to the nature of the mind in which these trans formations of sensation (sentir) were held to take place, a great part of the ideologists remained by Condillac's positivistic reserve ; others went on from Voltaire's problematical to Lamettrie's assertive mate rialism, — at first, in Hartley's fashion emphasising the thorough going dependence of combinations of ideas upon nervous processes, then with express maintenance of the materiality of the psychical activities. This development is most clearly to be seen in the case of Diderot. He set out from the position of Shaftesbury and Locke, but the sensualistic literature became more potent from step to step
1 In toe development of the practical series of conscious acta, the Influence of Descartes' and Spinoza's theory of the emotions and passions asserted itself with Condillac and his disciples, as also in part among the English associa- Uunal psychologists.
* It U not impossible that this nomenclature in case of de Tracy was intended to be the counterpart to Fichie's " Wissenschaftslehre," — Science of Knowl edge (cf. below. Pan VI. ch. 8).
458 The Enlightenment : Theoretical Questions. [Part V.
in the Editor of the Encyclopaedia ; he followed up the hypotheses of hylozoism1 (cf. below, § 34, 9), and finally took part in the com
of the Sy8thne de la Nature. This work set forth the human psychical activities within the framework of its metaphysics as the fine invisible motions of the nerves, and treated their genetic process just as Lamettrie had done. Among the later ideologists
Cabanis is prominent in this respect bf the newness of his physio logical point of view ; he takes account of the progress of natural science in so far as to seek the conditions of the nerves, to which man's psychical states (le moral) must be referred, no longer merely in mechanical motions, but in chemical changes. Ideation is the secretion of the brain, just as other secretions are produced by other organs.
In opposition to this, another line of ideology held fast to Locke's principle that all content of ideas may indeed be due to the senses, but that in the functions directed toward combining such content the peculiar character of the mind's nature shows itself. The leader of this line of thought was Bonnet. He, too, in a manner similar to that of Condillac, adopts the mode of consideration commended by Lamettrie, adverting to Arnobius, but he is much too well-schooled as an investigator of Nature to fail to see that sensation can never be resolved into elements of motion, that its relation to physical states is synthetic, but not analytic. Hence he sees in the mechanism of the nervous system only the causa occasionalis for the spontaneous reaction of the mind, and the substantiality of the mind seems to him to be proved by the unity of conscioumess. He connects with this theory all sorts of fantastic hypotheses. ' Religious ideas speak in his assumption of the immaterial mind-substance, but sensualism admits an activity of this substance only in connection with the body ; for this reason, in order to explain immortality and the un interrupted activity of the mind, Bonnet helps himself by the hypothesis of an aethereal body which is joined essentially with the soul and takes on a coarser material external organism, according to its dwelling-place in each particular case.
This union of sensualism with the maintenance of self-subsistent substantiality and capacity of reaction on the part of the mind passed over to Bonnet's countryman, Rousseau, who combated with its aid the psychological theories of the Encyclopaedists. He found that this characteristic quality of the mind, the unity of its function, evinces itself in feeling (sentiment), and opposed this original natu-
- ■ > The decisive transition-writing is cPAlembert's Dream. 2 In the Paling&netie* Philosophiques.
position
Chap. 1, § 33. ] Innate Ideas : Bonnet, Rousseau, Reid. 459
ralness of its essence to the cold and indifferent mechanism of ideas, which would debase the mind to an unconditional dependence upon the outer world. The feeling of individuality rebelled with him against a doctrine according to which there is nothing in man's consciousness but the play, as if upon an indifferent stage, of a mass of foreign contents accidentally coming together, which unite and then separate again. He wished to bring out the thought that it is not the case that the mental life merely takes place within us, but that it is rather true that we are ourselves present as actively deter mining personalities. This conviction dictated Rousseau's opposi tion to the intellectualistic Enlightenment, which in the sensualism of Gondii lac and of the Encyclopaedists wished to regard man's inner life as only a mechanical product of sensational elements excited from without: to psychological atomism Rousseau opposes the principle of the Monadology.
In the same manner, and perhaps not without influence from Rousseau in his arguments, St. Martin raised his voice against the prevailing system of Condillac ; he even came out of his mystical retreat to protest in the sessions of the Ecoles Normales ' against the superficiality of sensualism. The ideologists, he says, talk a great deal about human nature; but instead of observing it they devote their energies to put it together (composer).
8. The Scottish philosophers are the psychological opponents of sensualism in all its forms. The common ground on which this contrast developed is that of psychology regarded as philosophy.
For Reid, also, and his disciples seek the task of philosophy in the investigation of man and his mental capacities ; indeed, they fixed still more energetically and one-sidedly than the various schools of their opponents the methodical point of view that all philosophy must be empirical psychology. But this view of the human physi cal activity and its development is diametrically opposed to that of the sensualists. The latter hold the simple, the former the com plex, the latter the individual ideas, the former the judgments, the latter the sensuous, the former the internal, the latter the particular, the former the general, to be the original content of the mind's activity. Reid acknowledges that Berkeley's idealism and Hume's scepticism are as correct consequences from Locke's principle as is Hartley's materialism ; but just the absurdity of these consequences refutes the principle.
In opposition to this, Reid will now apply the Baconian method of induction to the facts of inner perception in order to attain by an
i Seances dts /■>. . Vorm. , UI. 01 ft
460 The Enlightenment: Theoretical Questions. [Part V.
analysis of these to the original tiiiths, which are given from the beginning in connection with the nature of the human mind, and which assert themselves in the development of its activities as determining principles. Thus, putting aside all help of physiology, the fundamental science psychology shall be perfected as a kind of natural science of inner observation. In the solution of this task, Reid himself, and after him especially Dugald Stewart, develop a considerable breadth and comprehensiveness of vision in the appre hension of the inner processes and a great acuteness in the analysis of their essential content : a multitude of valuable observations on
the genetic processes of the mental life is contained in their exten sive investigations. And yet these investigations lack in fruitful- ness of ideas as well as in energetically comprehensive cogency. For they everywhere confuse the demonstration of that which can be discovered as universally valid content in the psychical func tions, with the assumption that this is also genetically the original and determining : and since this philosophy has no other principle than that of psychological fact, it regards without criticism all that can in this manner be demonstrated to be actual content of mental activity, as self-evident truth. The sum-total of these principles is designated as common sense, and as such is held to form the supreme rule for all philosophical knowledge.
9. In the philosophy of the German Enlightenment all these tendencies mingle with the after-workings of the Cartesian and Leibnizian rationalism. The twofold tendency in the method of this latter system had taken on a fixed systematic form through the agency of Christian Wolff. According to him, all subjects should be regarded both from the point of view of the eternal truths and from that of the contingent truths : for every province of reality there is a knowledge through conceptions and another through facts, an a priori science proceeding from the intellect and an a posteriori science arising from perception. These two sciences were to combine in the result in such a way that, for example, em pirical psychology must show the actual existence in fact of all those activities which, in rational psychology, were deduced from the metaphysical conception of the soul, and from the " faculties " resulting from this conception. On the other hand, following Leib niz's precedent, the distinction in value of the two modes of knowl edge was so far retained as to regard only the intellectual knowledge as clear and distinct insight, while empirical (or, as they said at that time, historical) knowledge was regarded as a more or less obscure and confused idea of things.
Psychologically, the two kinds of knowledge were divided, in
Chap 1, § 33. ] Innate Ideas : Wolff, Lambert. 461
accordance with the Cartesian model, into the idea; innatat and the idem adventitim. Yet Wolff himself, agreeably to the metaphysical direction of his thought, laid less weight upon the genetic element. But the opposite was the case with his adherents and opponents, who were already standing under the influence of the French and
Knglish theories. The general course of the development was that the importance which Leibniz and Wolff had conceded to empiricism was increased more and more by the penetration of the Lockian
The psychological method gained the preponderance over the metaphysico-ontological step by step, and within the psy chological method increasing concessions were made to sensualism, of such a nature that ultimately not only earnest men of science like Rudiger and"Lossius, but especially a great part of the "popu lar philosophers supported completely the doctrine that all human ideas arise from sense-perception. The motley and irregular series of stages in which this process completed itself has only a literary- historical interest,1 because no new arguments came to light in con nection with it.
Only one of these men used the psychologico-epistemological dualism which prevailed in the German philosophy of the Enlight. enment, to make an original and fruitful turn. Heinrich Lambert,
who was fully abreast of the natural science of his time, had grown into intelligent sympathy with the mathematico-logical method as completely as he had into an insight into the worth of experience : and in the phenomenology of his New Qrganon, in attempting to fix the limits for the psychological significance of these two elements of knowledge, he disposed the mixture of the a priori and a posteriori constituents requisite for knowing reality, in a way that led to the distinction ofform and content in ideas. The content-elements of thought, he taught, can be given only by per
ception : but their mode of connection, the form of relation which is thought between them, is not given from without, but is a proper activity of the mind. This distinction could be read out of Locke's ambiguous exposition:1 but no one had conceived it so sharply and precisely from this point of view as Lambert. And this point of view was of great imj>ortanee for the genetic consideration of the ideas of the human mind. It followed from that was neither possible to derive the content from the mere form, nor the form of knowledge from the content. The first refuted the logical rational
Cf. W. Winilflband, Onrh. d. nrurrrn Phttntnphlr. $$ KUA.
Ct. thr dem'inmratlon in O. Harwnnwin, Lurke'i l. *hrt ron der mrn*r\ lieken Ertrnntniu in Vergleif. htmg mil Leibnis' KritUt dentil** (l^ipa 1801, Abhandl d. tHrht. On. d. WiMMtueh. ).
principles.
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462 the Enlightenment : Theoretical Questions. [Pam V.
ism with which Wolff would spin all ontology and metaphysics oat from the most general principles of logic, and ultimately from the one principle of contradiction ; the other took the basis away from sensualism, which thought that with the contents of perception the knowledge also of their relations was immediately given. Out of this grew for the " improvement of metaphysics " the task of dis solving out these relating forms from the total mass of experience, and of making clear their relation to content. But Lambert sought in vain for a single unifying principle for this purpose,1 and his " Archilektonik" finally contented itself with making a collection of them not based on any internal principle.
10. While all these theories as to the origin of human ideas were flying about in the literary market, the reconciling word upon the problem of innate ideas had been long spoken, but was waiting in a manuscript in the Hanoverian library for the powerful effect which its publication was to produce. Leibniz, in his Nouveaux Essais, had provided the Lockian ideology with a critical commentary in detail, and had embodied within it the deepest thoughts of his phi losophy and the finest conclusions of his Monadology.
Among the arguments with which Locke combated the doctrine that ideas were innate, had been that with which he maintained that there could be nothing in the mind of which the mind knew nothing. This principle had also been pronounced by him 2 in the form that the soul thinks not always. By this principle the Car tesian definition of the soul as a res cogitans was brought into ques tion : for the essential characteristic of a substance cannot be denied it at any moment. In this sense the question had been often dis cussed between the schools. Leibniz, however, was pointed by his Monadology to a peculiar intermediate position. Since, in his view, the soul, like every monad, is a " representing " power, it must have perceptions at every moment: but since all monads, even those which constitute matter, are souls, these perceptions cannot pos sibly all be clear and distinct. The solution of the problem lies, therefore, again in the conception of unconscious representations or
petites perceptions (cf. above, § 31). The soul (as every monad) always has ideas or representations, but not always conscious, not always clear and distinct ideas ; its life consists in the development of the unconscious to conscious, of the obscure and confused to clear and distinct ideas or representations.
In this aspect Leibniz now introduced an extremely significant
1 Thi* is best seen in his interesting correspondence with Kant, printed in the works of the latter.
« Essay II. 1, 10 f.
Chap. 1, § 33. ] Innate Idea* : Leibniz. 463
conception into psychology and epistemology. He distinguished between the states in which the soul merely has ideas, and those in which it is conscious of them. The former he designated as percep tion, the latter as apperception. 1 He understood, therefore, by apperception the process by which unconscious, obscure, and con fused representations are raised into clear and distinct consciousness, and thereby recognised by the soul as its own and ajypropriated by
The genetic process of the psychical life consists in the changing of unconscious into conscious representations or ideas, in taking up perceptions into the clearness and distinctness of self-
consciousness. In the light of the Monadology Leibniz's methodo logical view of the empirical or contingent truths (cf. § 30, 7) took on a peculiar colouring. The fact that the monads have no windows makes it impossible to conceive of perception metaphysically as a working of things upon the soul : * the ideas of sense, or sense-pres entations, must rather be thought as activities which the soul, by virtue of the pre-established harmony, develops in an obscure and confused manner (as petites perceptions), and the transformation which takes place in them can be regarded only as a process of making them distinct and of clearing them up, — as a taking up into self-consciousness, as apperception.
Sensibility and understanding, the distinction between which with Leibniz coincides with that of different degrees of clearness and distinctness, have, therefore, in his view, the same content, only
that the former has in obscure and confused representation what the latter possesses as clear and distinct. Nothing comes into the soul from without; that which it consciously represents has been already unconsciously contained within it: and on the other hand, the soul cannot bring forth anything in its conscious ideas which has not been within it from the beginning. Hence Leibniz must decide that in a certain sense, that is, unconsciously, all ideas are innate ; and that in another sense, that consciously, no idea innate in the human soul. He designates this relation, which had been previously sketched in the principles of the Monadology, by the name virtual innateness of ideas.
This thought, which at once treated as the controlling point of view at the opening of the New Essays, carried out especially with reference to the universal or eternal truths. This was indeed the burning question here the one party (the Neo-1'latonists, and in part the Cartesians) maintained that these were innate "axtu-
Print, it la Nat. el At la GrOrt, where the relationship with the Lockian redaction comes out strongly Xout. Em. II.
• . V. B. IV.
self-consciousness.
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464 The Enlightenment : Theoretical Questions. [Part V.
ally," as fully formed (fertige) truths; the others (Hobbes, and in part Locke) would explain them from the co-operation of sensa tional elements. Leibniz, however, carries out the thought that such principles are contained already in perception, as petites percep tions, that is, as the involuntary forms of relating thought, but that after this unconscious employment of them they are apperceived, that raised to clear and distinct consciousness and so recognised in connection with experience. The form of the soul's activity which afterwards brought to clearness and distinctness of intel lectual apprehension as universal principle, an eternal truth, inheres already in the sensuous representation, though unclear and confused. Hence while Locke had appropriated for his own use the scholastic principle nihil est in intellectu quod non fuerit in sensu, Leibniz adds thereto nisi intellectus ipse. 1
11. When the Nouveaux Essais were printed in 1765, they excited great attention. Lessing was translating them. That the life of the soul transcends all that clear and distinctly conscious, and rooted in obscurely presaged depths, was an insight of the highest value for the literature which was just struggling out of the intel lectual dryness of the Enlightenment, and out of insipid correctness to an unfolding full of genius, — and an insight all the more valua ble as coming from the same thinker that Germany honoured as the father and hero of its Enlightenment. In this direction Leibniz worked especially upon Herder: we see not only in his aesthetic views,' but still more in his prize essay " On the Knowing and Feel ing of the Human Soul. "
Under the preponderance of the methodological point of view, the Leibnizo-Wolffian school had strained the opposition between rational and empirical knowledge as far as possible, and had treated under standing and sensibility as two separate faculties. The Berlin Academy had wished to see the mutual relation of these two sepa rated powers, and the share which each has in human knowledge, investigated Herder played the true Leibniz — as the latter had developed himself in the Nouveaux Essais — against the prevailing system of the schools when he emphasised in his treatise the living unity of man's psychical life, and showed that sensibility and under standing are not two different sources of knowledge, but only the different stages of one and the same living activity with which the monad comprehends the universe within itself. All the ideas with which the soul raises itself in its development, step by step; from the consciousness of its immediate environment to the knowledge of
Nouv. Ess. II. Cf. principally the fourth Kritische Waldcken.
1
1, 2.
2
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Chap. 1, § 33. ] Innate Ideas : Herder, Kant. 465
the harmony of the universe, are innate within the soul as internal
This deeper unity of sensibility and understanding, Herder called feeling; and in this also in his inquiry as to the "Origin of Language," he found the function which embraces all senses like a unity, and by means of which the psycho-physical mechanism of producing and hearing sounds (Tonens and H&rens) is raised to
become the expression of thought.
12. More important still was another effect of the work of Leib
niz. It was no less a thinker than Kant who undertook to build up the doctrine of the Nouveaux Essais into a system of epistemology
(cf. § 34, 12). The Konigsberg philosopher was stimulated by that work to one of the most important turns in his development, and completed it in his Inaugural Dissertation. 1 He had already grown out of the Wolffian school-metaphysics and had been long employed with the examination of the empirical theories, and yet could not satisfy himself with them. * On the contrary, he was proceeding in the direction of establishing metaphysics upon a new basis, and was following Lambert's attempts to make a beginning at the work in connection with the distinction of form and content in knowledge. Now Leibniz showed with reference to the " eternal truths " that they inhered already as involuntary relating forms within sense experience itself, to be raised and brought to clear and distinct con sciousness by the reflection of the understanding. This principle of virtual innateness is the nerve of Kant's Inaugural Dissertation: the
metaphysical truths lie in the soul as laws of its activity,' to enter into active function on occasion of experience, and then to become object and content of the knowledge of the understanding.
Kant now applies this point of view in a new and fruitful manner to sensuous knowledge. From methodical reiisons he opposed this to intellectual knowledge much more sharply even than the Wolffians : but on this account the question for him was, whether there are perhaps in the world of the senses just such original form-relations as had been pointed out in the intellectual world by Leibniz and recognised by Kant himself (cf. 5 8, and the whole Sectio IV. of the treatise De mundi sensibilis et intelligibilix forma et principiis) : and thus he discovered the " pure Forms of the sensibility " — qxire and time. They are not innate in the ordinary sense, but acquired, yet not abstracted from the data of sensibility, but ab ipsa mentis
powers.
1 The dependence of this essay upon the Xoureaux Etsais has been shown by W. ' Windelband. Yiertetjahrtehr. f. u-Utensch. Philot. . I. , 1876, pp. 234 ft*.
Tills la best proved by the essay which apparently stands farthest removed from metaphysics. The Ihreamn of a (ihost Seer. Cf. also Part VI. ch. 1.
1 De Jtundi Sens, et Int.
, J 6: dantur per iptam naluram intellect in. Cf. | 8, aJao the corollary to f 8.
466 The Enlightenment : Theoretical Questions. [Part V.
actione secundum perpetuus leges sensa sua coordinante [from the very action of the mind co-ordinating its sensations according to perpetual laws], and like the intellectual Forms they are recognised by attending to the mind's activity on occasion of experience, — the business of mathematics.
Another formulation was given to the principle of virtual innate- ness by Tetens. He wrote his essays on human nature and its development under the impression received from Kant's Inaugural Dissertation. He, too, declares that the " acts of thought " are the first original relation-thoughts (Verhctttnissgedanken) : we learn them by applying them when we think; and thus they prove themselves to be the natural laws of thought. The universal prin ciples which lie at the basis of all philosophical knowledge are, accordingly, " subjective necessities " in which the essential nature of the thinking soul itself comes to consciousness.
§ 34. Knowledge of the Outer World.
The background of all these theories is their epistemological pur
This, however, assumes from the beginning a somewhat narrower place under the presupposition of the naive realism which became attached to the Cartesian metaphysics. The principle of the cogito ergo sum made the self-knowledge of the mind's nature appear as the original certainty, as that which was self-evident and immediately free from doubt ; but the greater the difference in kind which was conceived to exist between the world of consciousness and that of space and bodies, the greater the difficulties that pre sented themselves with reference to the possibility of knowing this latter world. This fact was taught at once by the metaphysical development immediately after Descartes (cf. § 31), and the same was now repeated in the most various forms in connection with the translation of these same thoughts into the language of empirical psychology and sensualism.
There is thus in the epistemology of modern philosophy from its beginning a superiority attributed to inner experience, by virtue of which knowledge of the outer world becomes problematical. In this an after- working of the Terminism, with which the Middle Ages had ended, asserts itself throughout the whole extent of modern thought as a determining mode of view : the heterogeneity of the outer and inner worlds gives the mind a proud feeling of a substantial quality peculiar to itself as contrasted with things, but at the same time a certain degree of uncertainty and doubtfulness in orienting itself in this world which is to it strange and foreign. In this way
pose.
Chap. 1, § 34. ] Knowledge of the Outer World : Locke. 467
the very statement of the fundamental problem in the philosophy of the Enlightenment shows itself to be an echo of that deepening of the mind within itself, that placing of consciousness upon an inde pendent basis over against the outer world, with which the ancient philosophy ended its course. In this was rooted the power of the Augustinian spirit over modern philosophy.
1. The preponderance of the inner experience asserts itself very strongly also with Locke, although in principle he placed sensation and reflection upon an equality psychologically, and in his genetic theory even made the latter dependent upon the former. But in assigning the epistemological values this relation is at once reversed in the spirit of the Cartesian principles. For the dualism of finite substances wjiich the great French metaphysician had propounded is quietly introduced by Locke in conjunction with the dualism of the sources of experience : sensation is designed to furnish knowledge of the corporeal outer world, reflection to give knowledge of the activities of the mind itself: and in this consideration it is naturally found that the latter is much more suited to its task than the former. Our knowledge of our own states is intuitive and the most certain of all ; and with a knowledge of our states we are at the same time perfectly and undoubtedly sure of our own existence also. Locke presents this doctrine of the certainty of knowledge of self with an almost verbal adherence to Descartes. ' With reference to our knowledge of the corporeal world, on the other hand, his attitude is much more reserved Such a knowledge is possible oi. 'y through sensation ; and although it still deserves the name knowledge, it yet lacks complete certainty and adequacy. Primarily, it is only the presence of the idea in the mind that is intuitively certain ; that a thing corresponds to the idea is not intuitively certain, and demon stration can at most teach that there is a thing there, but can predicate nothing concerning this thing.
To be sure, Locke is not at all in agreement with himself on this point. In connection with his theory of the ideas of sensation, he adopts the doctrine of the intellectual nature of the sense qualities quite in the form worked out by Descartes (cf. § 31, 2), designates them happily by the distinction of primary and secondary qualities, adds, as tertiary qualities, such powers as express the relation of one body to another, declares primary qualities to be those which really belong to bodies in themselves, and reckons, also, impenetrability in this class, in addition to those assigned to it by Descartes. As compared with the doctrine of Hobbes, this is in its essence a
> Kt$at IV. A, 3.
468 The Enlightenment : Theoretical Question*. [Part V.
decided relapse into the mode of thought of Democritus and Epicurus, as is shown, also, in the fact that Locke follows the theory of images in tracing stimulations • to the affection of the nerves by minute particles streaming out from objects. 1 On the whole, there fore, the fundamental Cartesian basis of mathematical knowledge of Nature is here reaffirmed, and even more widely extended.
But Locke's decision in connection with his analysis of the idea of substance has an entirely different purport. Like Occam, he distinguishes from intuitive knowledge and knowledge given by sensation, demonstrative knowledge: this has to do, not with the relation of ideas to the outer world, but with the relation of ideas to one another. In its value as knowledge it stands after the intui tive, but superior to the sensitive. 5 Demonstrative thinking is then conceived of entirely terministically, something as in the case of Hobbes, as a reckoning with concept signs. The necessity attach ing to the demonstration holds only within the world of ideas ; it concerns, as one class, general or abstract ideas to which no proper reality corresponds in natura rerum. If ideas are once present, judgments may be formed concerning the relations which exist between them, quite apart from any reference to the things them selves; and it is with such judgments alone that demonstrative knowledge has to do. Such "complex" ideas are thought-things, which, after they have been fixed by definition, can enter into the union with others determined in each case by the respective con tents, without thereby acquiring any relation to the outside world. Among these modes of union, that which is expressed by the idea of substance (the category of inherence) is conspicuous in an especial manner. For all other contents and relations can be thought only as belonging to some substance. This relation, therefore, has Reality, — the idea of substance according to Locke's expression, ectypal, — but only in the sense that we are forced to assume real substrate for the modes given in particular ideas, without being able to make any assertion as to what this substrate itself is. Substance is the supporter, itself unknown, of known qualities, which we have occa sion to assume belong together.
This view that substances are unknowable does not, indeed, hinder Locke from taking in hand at another passage,8 in an entirely Cartesian fashion, a division of all substances into " cogitative and incogitative. " On the other hand, he applies the view to his treat-
Essay, II. IT. Cf. also B. Rlittenauer, Zur VorgescMchte des Idealism*! und Kriticismus (Freiburg, 1882), and Geil, op. cit. , pp. 66 ft".
lb. IV. 2.
»Ib. II. 23,20; IV. 10. 9.
»1
8, 7
a
is,
Chap. 1, § 34. ] Knowledge of the Order World : Berkeley . 469
roent of the cogito ergo sum. This principle he carries over entirely from the metaphysical realm into that of empirical psychology. . . Self-certainty is for him thafr^jftne " internal sense " ; intuition in this case refers only to our states and activities, not to our essence ; it shows us, indeed, immediately and without doubt, that we are, but not what we are. The question a^ to the substance of the soul (and accordingly the question als»> As torts relation to the body) is as incapable of an answer as the question as to the " what" of any substance whatever.
Nevertheless, Locke holds it to be possible to gain a demonstrative certainty of the existence of Ood. For this purpose he adopts the first of the Cartesian proofs (cf. § 30, 5) in a somewhat modified form, and adds the ordinary cosmological argument An infinite, eternal, and perfect being must be thought, an ultimate cause of finite substances of which man intuitively knows himself to be one.
So manifold and full of contradictions are the motifs which cross in Locke's doctrine of knowledge. The exposition, apparently so easy and transparent, to which he diluted Cartesianism, glides over and away from the eddies which come up out of the dark depths of its historical presuppositions. But as the ambiguous, indeterminate nature of his psychology unfolded itself in the antithesis in the fol lowing developments, so, too, this episteinological metaphysics offered points of departure for the most varied transformations.
2. The very first of these shows an audacious energy of one-sided- ness in contrast with the indecisiveness of Locke. Berkeley brought the ascendeucy of inner experience to complete dominance by putting an end to the wavering position which Locke had taken upon the question as to the knowledge of bodies. This he did with the aid of his extreme Nominalism and with a return to the doctrines of Hobbes. He demolished the conception of corporeal substance. Ac cording to the distinction of primary and secondary qualities, it was held that a part of that complex of ideas which perception presents us as a body should be separated out, and another part retained as alone real; but this distinction, as Hobbes had already taught (cf. f 31, 2), is in the nature of the case erroneous. The "mathe matical " qualities of ladies are as truly ideas within us as the sense qualities, and Berkeley had demonstrated exactly this point with analogous arguments in his Theory of Vi»ion. He attacks the warrant of the distinction of Descartes (and of Democritus). But while, according to this view, all qualities of bodies without excep
tion are ideas in us, Locke has retained as their real supporter a superfluous unknowable "substance " ; in a similar way others speak of matter as the substrate of sensible qualities.
470 The Enlightenment : Theoretical Questions. [Part V.
But in all these cases, says Berkeley, it is demanded of us to regard an abstraction as the only actual reality. Abstract ideas, however, do not exist, — they do not exist even in the mind, to say nothing of existing in natura rerum. Locke was then quite right in saying that no one could know this "substance ": no one can even think it; it is a fiction of the schools. For the naive consciousness, for "common sense," whose cause Berkeley professes to maintain against the artificial subtlety of philosophers, bodies are just exactly what is perceived, no more and no less ; it is only the philosophers who 3eek for something else behind what is perceived, — something mysterious, abstract, of which they themselves cannot say what it is. For the unperverted mind, body is what one sees, touches, tastes, smells, and hears : its esse is percipi.
Body is then nothing but a complex of ideas. If we abstract from a cherry all the qualities which can be perceived through any of the senses, what is left ? Nothing. The idealism which sees in a body nothing farther than a bundle of ideas is the view of the common man ; it should be that of philosophers also. Bodies possess no other reality than that of being perceived. It is false to suppose that there is in addition to this a substance inherent within them, which "appears" in their qualities. They are nothing but the sum of these qualities.
In reply to the question that lies close at hand, in what the differ ence consists between the " real " or actual body and that which is only imagined or dreamed of, if all bodies are only perceived, Berkeley answers with a spiritualistic metaphysics. The ideas which constitute the existence of the outer world are activities of spirits. Of the two Cartesian worlds only one has substantial existence ; only the res cogitantes are real substances, the res extensa are their ideas. But to finite spirits the ideas are given, and the origin of all ideas is to be sought only in the infinite Spirit, in God. The reality of bodies consists, therefore, in this, that their ideas are
communicated by God to finite spirits, and the order of succession in which God habitually does this we call laws of Nature. Hence Bishop Berkeley finds no metaphysical difficulty in supposing that God under certain circumstances departs from the usual order for some especial end, and in this case man speaks of miracles. Ou the other hand, a body is unreal which is presented only in the indi vidual mind according to the mechanism of memory or imagination, and without being at the same time communicated to the mind by God. And finally, since the actual corporeal world is thus changed into a system of ideas willed by God, the purposiveness which its arrangement and the order of its changes exhibit gives rise to no further oroblem.
Chap. 1, § 34. ] Knowledge of the Outer World : Collier. 471
The parallelism between this inference from Locke and that which Malebranche had drawn from Descartes is unmistakable ; and Malebranche and Berkeley are also at one in holding that God alone is the active force in the world, and that no individual thing is efficiently operative (cf. § 31, 8). It is extremely interesting to see how the extreme Realism of the Frenchman and the extreme Nominalism of the Englishman amount to the same thing. The grounds on which the views are based could not be more different : the result is the same. For what still separated the two could be easily removed out of the way. This was proved by a contemporary and countryman of Berkeley's, Arthur Collier (1680-1732) in his interesting treatise Clavis Universalis. 1 Malebranche,1 indeed, as a Cartesian, had not directly demurred to the reality of the corporeal world, but had held that we could understand the knowledge of this world by man, only on the hypothesis that the ideas of bodies in God are the common original, in accordance with which God pro duces, on the one hand, the actual bodies, and, on the other, the
ideas of these bodies in finite minds. Collier showed now that in this theory the reality of the corporeal world played a completely superfluous rSle : since no actual relation between the corporeal world and human ideas is assumed, the value of human ideas for knowledge remains quite the same if we posit only an ideal cor poreal world in God, and regard this as the real object of human knowledge.
The idealism, which proceeded in this way from the cogito ergo turn along several paths, was attended by still another paradox as a by-product, which is occasionally mentioned in the literature of the eighteenth century without any definite name or form. Each individual mind has certain, intuitive knowledge only of itself and of its states, nor does it know anything of other minds
through ideas, which refer primarily to bodies and by an argument from analogy are interpreted to indicate minds. If, however, the whole corporeal world is only an idea in the mind, every individual is ultimately certain only of his own existence ; the reality of all else, all other minds not excluded, is problematical and cannot be demonstrated. This doctrine was at that time designated as Egoism, now it is usually called Solipsism. It is a metaphysical
1 The alternative title of the book reads, A Xev> Inquiry after Trvth. being m Demonstration of the Son-Existence or Impossibility of an External World
It wwi edited together with Berkeley's treat in* in the (iennan •• Collection of the Principal Writings which deny the Reality of their oxen Body ( . '. ') and of the tehole Corporeal World," by Kechenbach (Koitock. 1766).
* Wh<>«e doctrine had become known in England by the agency especially of John Sorris (Essai (Tun Theorie du Monde Idial, Lond. 1704).
(Lond. 1123).
except
472 Tlit EnliyhteniHtnt : Theoretical Questions. [Part V
sport which must be left to the taste of the individual; for the solipsist refutes himself by beginning to prove his doctrine to others.
Thus, following in the train of the Meditations, in which Descartes recognised self-consciousness as the rescuing rock in the sea of doubt, the result was finally reached which Kant later characterised as a scandal to philosophy ; namely, that a proof was demanded for the reality of the outer world, and none adequate could be found. The French materialists declared that Berkeley's doctrine was an insane delusion, but was irrefutable.
3. The transformation of Locke's doctrine by Berkeley leads farther in a direct line to Hume's theory of knowledge. To the nominalistic denial of abstract ideas the penetrative and profound Scot attached his distinction of all intellectual functions into im pressions, and ideas which are copies of impressions ; and coincident with his distinction is that of intuitive and demonstrative knowl edge. Each kind of knowledge has its own kind of certainty. Intuitive knowledge consists simply in the affirmation of actually present impressions. What impressions I have, I can declare with absolute certainty. I can make no mistake in this, in so far as I keep within the bounds of simply stating that I have a perception possessing this or that simple or complex content, without adding any conceptions which would put any interpretation upon this content.
As among the most important of these impressions which have immediate intuitive certainty Hume reckons the relations in space and time of the contents of sensation, — the fixing of the co-exist ence or succession of elementary impressions. The spatial order in which the contents of perception present themselves is undoubtedly given immediately with the contents themselves, and we likewise possess a sure impression as to whether the different contents are perceived at the same time or in succession. Contiguity in space and time is therefore intuitively given together with the impres sions, and of these facts the human mind possesses a knowledge which is perfectly certain and in nowise to be questioned. Only,
in characterising Hume's doctrine, it must not be forgotten that this absolutely certain matter-of-fact quality, which belongs to impressions, is solely that of their presence as mental states. In this meaning and restriction intuitive knowledge embraces not only the facts of inner experience, but also those of outer experience, but at the price of recognising that the latter are properly only species of the former, — a knowledge, that of mental states.
Contiguity in space and time however, but the most elementary
is,
is,
Chap. J, $ 34. ] Knowledge of the Outer World: Hume. 478
form of association between perceptions ; besides this Hume reckons two other laws, those of resemblance (or contrast, respectively) and causality. As regards the former of these two forms of relation, we hare a clear and distinct impression of the likeness or unlike- ness of sensations, and of the different degrees of these ; it consists in the knowledge of the degree of resemblance in our own (sensi tive) action, and belongs therefore to the impressions of the inner sense, which Locke called reflection. On this is based, consequently, a demonstrative knowledge of complete certainty ; it concerns the forms of that comparison between magnitudes which we perform upon the given contents of our ideas, and is nothing but an analysis of the regularity with which this takes place. This demonstrative science is mathematics ; it develops the laws of equality and propor tion with reference to numbers and space, and Hume is inclined to concede a still higher epistemological value to arithmetic than to geometry. 1
4. But mathematics is also the sole demonstrative science; and is that just because it relates to nothing else than the possible rela tions between contents of ideas, and asserts nothing whatever as to any relation of these to a real world. In this way the terministic principle of Hobbes (cf. § 30, 3) is in complete control with Hume, but the latter proceeds still more consistently with his limitation of this theory to pure mathematics. Fo»Hume declares that no asser tion respecting the external world is capable of demonstration ; all our knowledge is limited to the ascertaining and verifying of
impressions, other.
and to the relations of these mental states to each
Hence it seems to Hume an unauthorised trenching of thought beyond its own territory, when the resemblance between ideas is interpreted as meaning metaphysical identity ; this is the case in
every employment of the conception of substance. Whence is this conception ? It is not perceived, it is not found as a content either in particular sensations or in their relations; substance is the unknown, indescribable support of the known contents of ideas. Whence this idea for which no impression is to be found in the whole circuit of sensations as its necessary original ? Its origin is to be sought in reflection. It is the copy of a frequei tly repeated
conjunction of ideas. By the repeated being together of impres sions, by the custom of the like ideational process there arises by virtue of the law of association of ideas the necessity of the idea of their co-existence, and the feeling of this associative necessity of the
' Treat. I. 2, 1 ; I. 3, 1.
474 The Enlightenment : Theoretical Questions. [Part V.
ideational process is thought as a real belonging together of the elements of association, i. e. as substance.
The thought-form of inherence is thus psychologically explained, and at the same time epistemologically rejected; nothing corre sponds to it further than the feeling of a likeness in the ideational conjunction ; and since we can never know anything of existence except by immediate sense-perception, the Reality of the idea of substance is incapable of proof. It is clear that Hume thus makes Berkeley's doctrine his own, so far as it concerns corporeal things.
But Berkeley had but half done his work upon the idea of substance. He found that bodies are only complexes of sensations ; that their being is identical with their being perceived ; that there is no sense or meaning in hypostatising their belonging together, as an unknown substance : but he let the psychical substances, spirits, the res cogi- tantes, stand ; he regarded them as the supports or agents in which all these ideational activities inhere. Hume's argument applies to this latter class also. What Berkeley showed of the cherry is true also of the " self. " Inner perception, also (such was the form which it had actually taken on already with Locke; cf. above, No. 1), shows only activities, states, qualities. Take these away, and noth ing remains of Descartes' res cogiians either : only the " custom " of constant conjunction of ideas in imagination is at the basis of the conception of a "mind"; the self is only a " bundle of perceptions. " '
The same consideration holds also, mxttatis mutandis, for causality, that form under which the necessary connection between contents of ideas is usually thought : but this is neither intuitively nor de monstratively certain. The relation of cause and effect is not per ceived ; all that we can perceive by the senses is the relation in time, according to which one regularly follows the other. If, now, thought interprets this sequence into a consequence, this post hoc into a propter hoc,1 this too has no basis in the content of the ideas causally related to each other. From a "cause" it is not possible to deduce logically its " effect " ; the idea of an effect does not con tain within it that of its cause. It is not possible to understand the causal relation analytically. ' Its explanation is, according to
1 Treat.
finally, the moral will. So knowledge and morality grow upon the soil of the sensibility.
This systematic construction had great success. The systematic impulse, which was repressed in the metaphysical field (cf. § 34, 7), threw itself with all the greater energy upon this "analyst* of the hnman mind" as a substitute; and as Condillac himself had already woven many acute observations into his exposition of the develop ment process, so a whole throng of adherents found opportunity to take part in the completion of this stiucture by slight changes and sin[tings of the phases, by innovations in nomenclature and by more or less valuable deductions. The Government of the . Revolu tion recognised as philosophy only this study of the empirical development of intelligence, and Destutt de Tracy gave it later the name "Ideology. ''1 So it came about that at the beginning of our century philosophers were in France usually called ideologists.
7. With reference to the nature of the mind in which these trans formations of sensation (sentir) were held to take place, a great part of the ideologists remained by Condillac's positivistic reserve ; others went on from Voltaire's problematical to Lamettrie's assertive mate rialism, — at first, in Hartley's fashion emphasising the thorough going dependence of combinations of ideas upon nervous processes, then with express maintenance of the materiality of the psychical activities. This development is most clearly to be seen in the case of Diderot. He set out from the position of Shaftesbury and Locke, but the sensualistic literature became more potent from step to step
1 In toe development of the practical series of conscious acta, the Influence of Descartes' and Spinoza's theory of the emotions and passions asserted itself with Condillac and his disciples, as also in part among the English associa- Uunal psychologists.
* It U not impossible that this nomenclature in case of de Tracy was intended to be the counterpart to Fichie's " Wissenschaftslehre," — Science of Knowl edge (cf. below. Pan VI. ch. 8).
458 The Enlightenment : Theoretical Questions. [Part V.
in the Editor of the Encyclopaedia ; he followed up the hypotheses of hylozoism1 (cf. below, § 34, 9), and finally took part in the com
of the Sy8thne de la Nature. This work set forth the human psychical activities within the framework of its metaphysics as the fine invisible motions of the nerves, and treated their genetic process just as Lamettrie had done. Among the later ideologists
Cabanis is prominent in this respect bf the newness of his physio logical point of view ; he takes account of the progress of natural science in so far as to seek the conditions of the nerves, to which man's psychical states (le moral) must be referred, no longer merely in mechanical motions, but in chemical changes. Ideation is the secretion of the brain, just as other secretions are produced by other organs.
In opposition to this, another line of ideology held fast to Locke's principle that all content of ideas may indeed be due to the senses, but that in the functions directed toward combining such content the peculiar character of the mind's nature shows itself. The leader of this line of thought was Bonnet. He, too, in a manner similar to that of Condillac, adopts the mode of consideration commended by Lamettrie, adverting to Arnobius, but he is much too well-schooled as an investigator of Nature to fail to see that sensation can never be resolved into elements of motion, that its relation to physical states is synthetic, but not analytic. Hence he sees in the mechanism of the nervous system only the causa occasionalis for the spontaneous reaction of the mind, and the substantiality of the mind seems to him to be proved by the unity of conscioumess. He connects with this theory all sorts of fantastic hypotheses. ' Religious ideas speak in his assumption of the immaterial mind-substance, but sensualism admits an activity of this substance only in connection with the body ; for this reason, in order to explain immortality and the un interrupted activity of the mind, Bonnet helps himself by the hypothesis of an aethereal body which is joined essentially with the soul and takes on a coarser material external organism, according to its dwelling-place in each particular case.
This union of sensualism with the maintenance of self-subsistent substantiality and capacity of reaction on the part of the mind passed over to Bonnet's countryman, Rousseau, who combated with its aid the psychological theories of the Encyclopaedists. He found that this characteristic quality of the mind, the unity of its function, evinces itself in feeling (sentiment), and opposed this original natu-
- ■ > The decisive transition-writing is cPAlembert's Dream. 2 In the Paling&netie* Philosophiques.
position
Chap. 1, § 33. ] Innate Ideas : Bonnet, Rousseau, Reid. 459
ralness of its essence to the cold and indifferent mechanism of ideas, which would debase the mind to an unconditional dependence upon the outer world. The feeling of individuality rebelled with him against a doctrine according to which there is nothing in man's consciousness but the play, as if upon an indifferent stage, of a mass of foreign contents accidentally coming together, which unite and then separate again. He wished to bring out the thought that it is not the case that the mental life merely takes place within us, but that it is rather true that we are ourselves present as actively deter mining personalities. This conviction dictated Rousseau's opposi tion to the intellectualistic Enlightenment, which in the sensualism of Gondii lac and of the Encyclopaedists wished to regard man's inner life as only a mechanical product of sensational elements excited from without: to psychological atomism Rousseau opposes the principle of the Monadology.
In the same manner, and perhaps not without influence from Rousseau in his arguments, St. Martin raised his voice against the prevailing system of Condillac ; he even came out of his mystical retreat to protest in the sessions of the Ecoles Normales ' against the superficiality of sensualism. The ideologists, he says, talk a great deal about human nature; but instead of observing it they devote their energies to put it together (composer).
8. The Scottish philosophers are the psychological opponents of sensualism in all its forms. The common ground on which this contrast developed is that of psychology regarded as philosophy.
For Reid, also, and his disciples seek the task of philosophy in the investigation of man and his mental capacities ; indeed, they fixed still more energetically and one-sidedly than the various schools of their opponents the methodical point of view that all philosophy must be empirical psychology. But this view of the human physi cal activity and its development is diametrically opposed to that of the sensualists. The latter hold the simple, the former the com plex, the latter the individual ideas, the former the judgments, the latter the sensuous, the former the internal, the latter the particular, the former the general, to be the original content of the mind's activity. Reid acknowledges that Berkeley's idealism and Hume's scepticism are as correct consequences from Locke's principle as is Hartley's materialism ; but just the absurdity of these consequences refutes the principle.
In opposition to this, Reid will now apply the Baconian method of induction to the facts of inner perception in order to attain by an
i Seances dts /■>. . Vorm. , UI. 01 ft
460 The Enlightenment: Theoretical Questions. [Part V.
analysis of these to the original tiiiths, which are given from the beginning in connection with the nature of the human mind, and which assert themselves in the development of its activities as determining principles. Thus, putting aside all help of physiology, the fundamental science psychology shall be perfected as a kind of natural science of inner observation. In the solution of this task, Reid himself, and after him especially Dugald Stewart, develop a considerable breadth and comprehensiveness of vision in the appre hension of the inner processes and a great acuteness in the analysis of their essential content : a multitude of valuable observations on
the genetic processes of the mental life is contained in their exten sive investigations. And yet these investigations lack in fruitful- ness of ideas as well as in energetically comprehensive cogency. For they everywhere confuse the demonstration of that which can be discovered as universally valid content in the psychical func tions, with the assumption that this is also genetically the original and determining : and since this philosophy has no other principle than that of psychological fact, it regards without criticism all that can in this manner be demonstrated to be actual content of mental activity, as self-evident truth. The sum-total of these principles is designated as common sense, and as such is held to form the supreme rule for all philosophical knowledge.
9. In the philosophy of the German Enlightenment all these tendencies mingle with the after-workings of the Cartesian and Leibnizian rationalism. The twofold tendency in the method of this latter system had taken on a fixed systematic form through the agency of Christian Wolff. According to him, all subjects should be regarded both from the point of view of the eternal truths and from that of the contingent truths : for every province of reality there is a knowledge through conceptions and another through facts, an a priori science proceeding from the intellect and an a posteriori science arising from perception. These two sciences were to combine in the result in such a way that, for example, em pirical psychology must show the actual existence in fact of all those activities which, in rational psychology, were deduced from the metaphysical conception of the soul, and from the " faculties " resulting from this conception. On the other hand, following Leib niz's precedent, the distinction in value of the two modes of knowl edge was so far retained as to regard only the intellectual knowledge as clear and distinct insight, while empirical (or, as they said at that time, historical) knowledge was regarded as a more or less obscure and confused idea of things.
Psychologically, the two kinds of knowledge were divided, in
Chap 1, § 33. ] Innate Ideas : Wolff, Lambert. 461
accordance with the Cartesian model, into the idea; innatat and the idem adventitim. Yet Wolff himself, agreeably to the metaphysical direction of his thought, laid less weight upon the genetic element. But the opposite was the case with his adherents and opponents, who were already standing under the influence of the French and
Knglish theories. The general course of the development was that the importance which Leibniz and Wolff had conceded to empiricism was increased more and more by the penetration of the Lockian
The psychological method gained the preponderance over the metaphysico-ontological step by step, and within the psy chological method increasing concessions were made to sensualism, of such a nature that ultimately not only earnest men of science like Rudiger and"Lossius, but especially a great part of the "popu lar philosophers supported completely the doctrine that all human ideas arise from sense-perception. The motley and irregular series of stages in which this process completed itself has only a literary- historical interest,1 because no new arguments came to light in con nection with it.
Only one of these men used the psychologico-epistemological dualism which prevailed in the German philosophy of the Enlight. enment, to make an original and fruitful turn. Heinrich Lambert,
who was fully abreast of the natural science of his time, had grown into intelligent sympathy with the mathematico-logical method as completely as he had into an insight into the worth of experience : and in the phenomenology of his New Qrganon, in attempting to fix the limits for the psychological significance of these two elements of knowledge, he disposed the mixture of the a priori and a posteriori constituents requisite for knowing reality, in a way that led to the distinction ofform and content in ideas. The content-elements of thought, he taught, can be given only by per
ception : but their mode of connection, the form of relation which is thought between them, is not given from without, but is a proper activity of the mind. This distinction could be read out of Locke's ambiguous exposition:1 but no one had conceived it so sharply and precisely from this point of view as Lambert. And this point of view was of great imj>ortanee for the genetic consideration of the ideas of the human mind. It followed from that was neither possible to derive the content from the mere form, nor the form of knowledge from the content. The first refuted the logical rational
Cf. W. Winilflband, Onrh. d. nrurrrn Phttntnphlr. $$ KUA.
Ct. thr dem'inmratlon in O. Harwnnwin, Lurke'i l. *hrt ron der mrn*r\ lieken Ertrnntniu in Vergleif. htmg mil Leibnis' KritUt dentil** (l^ipa 1801, Abhandl d. tHrht. On. d. WiMMtueh. ).
principles.
*•
it, I.
it
462 the Enlightenment : Theoretical Questions. [Pam V.
ism with which Wolff would spin all ontology and metaphysics oat from the most general principles of logic, and ultimately from the one principle of contradiction ; the other took the basis away from sensualism, which thought that with the contents of perception the knowledge also of their relations was immediately given. Out of this grew for the " improvement of metaphysics " the task of dis solving out these relating forms from the total mass of experience, and of making clear their relation to content. But Lambert sought in vain for a single unifying principle for this purpose,1 and his " Archilektonik" finally contented itself with making a collection of them not based on any internal principle.
10. While all these theories as to the origin of human ideas were flying about in the literary market, the reconciling word upon the problem of innate ideas had been long spoken, but was waiting in a manuscript in the Hanoverian library for the powerful effect which its publication was to produce. Leibniz, in his Nouveaux Essais, had provided the Lockian ideology with a critical commentary in detail, and had embodied within it the deepest thoughts of his phi losophy and the finest conclusions of his Monadology.
Among the arguments with which Locke combated the doctrine that ideas were innate, had been that with which he maintained that there could be nothing in the mind of which the mind knew nothing. This principle had also been pronounced by him 2 in the form that the soul thinks not always. By this principle the Car tesian definition of the soul as a res cogitans was brought into ques tion : for the essential characteristic of a substance cannot be denied it at any moment. In this sense the question had been often dis cussed between the schools. Leibniz, however, was pointed by his Monadology to a peculiar intermediate position. Since, in his view, the soul, like every monad, is a " representing " power, it must have perceptions at every moment: but since all monads, even those which constitute matter, are souls, these perceptions cannot pos sibly all be clear and distinct. The solution of the problem lies, therefore, again in the conception of unconscious representations or
petites perceptions (cf. above, § 31). The soul (as every monad) always has ideas or representations, but not always conscious, not always clear and distinct ideas ; its life consists in the development of the unconscious to conscious, of the obscure and confused to clear and distinct ideas or representations.
In this aspect Leibniz now introduced an extremely significant
1 Thi* is best seen in his interesting correspondence with Kant, printed in the works of the latter.
« Essay II. 1, 10 f.
Chap. 1, § 33. ] Innate Idea* : Leibniz. 463
conception into psychology and epistemology. He distinguished between the states in which the soul merely has ideas, and those in which it is conscious of them. The former he designated as percep tion, the latter as apperception. 1 He understood, therefore, by apperception the process by which unconscious, obscure, and con fused representations are raised into clear and distinct consciousness, and thereby recognised by the soul as its own and ajypropriated by
The genetic process of the psychical life consists in the changing of unconscious into conscious representations or ideas, in taking up perceptions into the clearness and distinctness of self-
consciousness. In the light of the Monadology Leibniz's methodo logical view of the empirical or contingent truths (cf. § 30, 7) took on a peculiar colouring. The fact that the monads have no windows makes it impossible to conceive of perception metaphysically as a working of things upon the soul : * the ideas of sense, or sense-pres entations, must rather be thought as activities which the soul, by virtue of the pre-established harmony, develops in an obscure and confused manner (as petites perceptions), and the transformation which takes place in them can be regarded only as a process of making them distinct and of clearing them up, — as a taking up into self-consciousness, as apperception.
Sensibility and understanding, the distinction between which with Leibniz coincides with that of different degrees of clearness and distinctness, have, therefore, in his view, the same content, only
that the former has in obscure and confused representation what the latter possesses as clear and distinct. Nothing comes into the soul from without; that which it consciously represents has been already unconsciously contained within it: and on the other hand, the soul cannot bring forth anything in its conscious ideas which has not been within it from the beginning. Hence Leibniz must decide that in a certain sense, that is, unconsciously, all ideas are innate ; and that in another sense, that consciously, no idea innate in the human soul. He designates this relation, which had been previously sketched in the principles of the Monadology, by the name virtual innateness of ideas.
This thought, which at once treated as the controlling point of view at the opening of the New Essays, carried out especially with reference to the universal or eternal truths. This was indeed the burning question here the one party (the Neo-1'latonists, and in part the Cartesians) maintained that these were innate "axtu-
Print, it la Nat. el At la GrOrt, where the relationship with the Lockian redaction comes out strongly Xout. Em. II.
• . V. B. IV.
self-consciousness.
4, 6.
;
:
is
9, 4.
is
1
i,
is
is,
464 The Enlightenment : Theoretical Questions. [Part V.
ally," as fully formed (fertige) truths; the others (Hobbes, and in part Locke) would explain them from the co-operation of sensa tional elements. Leibniz, however, carries out the thought that such principles are contained already in perception, as petites percep tions, that is, as the involuntary forms of relating thought, but that after this unconscious employment of them they are apperceived, that raised to clear and distinct consciousness and so recognised in connection with experience. The form of the soul's activity which afterwards brought to clearness and distinctness of intel lectual apprehension as universal principle, an eternal truth, inheres already in the sensuous representation, though unclear and confused. Hence while Locke had appropriated for his own use the scholastic principle nihil est in intellectu quod non fuerit in sensu, Leibniz adds thereto nisi intellectus ipse. 1
11. When the Nouveaux Essais were printed in 1765, they excited great attention. Lessing was translating them. That the life of the soul transcends all that clear and distinctly conscious, and rooted in obscurely presaged depths, was an insight of the highest value for the literature which was just struggling out of the intel lectual dryness of the Enlightenment, and out of insipid correctness to an unfolding full of genius, — and an insight all the more valua ble as coming from the same thinker that Germany honoured as the father and hero of its Enlightenment. In this direction Leibniz worked especially upon Herder: we see not only in his aesthetic views,' but still more in his prize essay " On the Knowing and Feel ing of the Human Soul. "
Under the preponderance of the methodological point of view, the Leibnizo-Wolffian school had strained the opposition between rational and empirical knowledge as far as possible, and had treated under standing and sensibility as two separate faculties. The Berlin Academy had wished to see the mutual relation of these two sepa rated powers, and the share which each has in human knowledge, investigated Herder played the true Leibniz — as the latter had developed himself in the Nouveaux Essais — against the prevailing system of the schools when he emphasised in his treatise the living unity of man's psychical life, and showed that sensibility and under standing are not two different sources of knowledge, but only the different stages of one and the same living activity with which the monad comprehends the universe within itself. All the ideas with which the soul raises itself in its development, step by step; from the consciousness of its immediate environment to the knowledge of
Nouv. Ess. II. Cf. principally the fourth Kritische Waldcken.
1
1, 2.
2
a
:
it
is
is
is
is,
Chap. 1, § 33. ] Innate Ideas : Herder, Kant. 465
the harmony of the universe, are innate within the soul as internal
This deeper unity of sensibility and understanding, Herder called feeling; and in this also in his inquiry as to the "Origin of Language," he found the function which embraces all senses like a unity, and by means of which the psycho-physical mechanism of producing and hearing sounds (Tonens and H&rens) is raised to
become the expression of thought.
12. More important still was another effect of the work of Leib
niz. It was no less a thinker than Kant who undertook to build up the doctrine of the Nouveaux Essais into a system of epistemology
(cf. § 34, 12). The Konigsberg philosopher was stimulated by that work to one of the most important turns in his development, and completed it in his Inaugural Dissertation. 1 He had already grown out of the Wolffian school-metaphysics and had been long employed with the examination of the empirical theories, and yet could not satisfy himself with them. * On the contrary, he was proceeding in the direction of establishing metaphysics upon a new basis, and was following Lambert's attempts to make a beginning at the work in connection with the distinction of form and content in knowledge. Now Leibniz showed with reference to the " eternal truths " that they inhered already as involuntary relating forms within sense experience itself, to be raised and brought to clear and distinct con sciousness by the reflection of the understanding. This principle of virtual innateness is the nerve of Kant's Inaugural Dissertation: the
metaphysical truths lie in the soul as laws of its activity,' to enter into active function on occasion of experience, and then to become object and content of the knowledge of the understanding.
Kant now applies this point of view in a new and fruitful manner to sensuous knowledge. From methodical reiisons he opposed this to intellectual knowledge much more sharply even than the Wolffians : but on this account the question for him was, whether there are perhaps in the world of the senses just such original form-relations as had been pointed out in the intellectual world by Leibniz and recognised by Kant himself (cf. 5 8, and the whole Sectio IV. of the treatise De mundi sensibilis et intelligibilix forma et principiis) : and thus he discovered the " pure Forms of the sensibility " — qxire and time. They are not innate in the ordinary sense, but acquired, yet not abstracted from the data of sensibility, but ab ipsa mentis
powers.
1 The dependence of this essay upon the Xoureaux Etsais has been shown by W. ' Windelband. Yiertetjahrtehr. f. u-Utensch. Philot. . I. , 1876, pp. 234 ft*.
Tills la best proved by the essay which apparently stands farthest removed from metaphysics. The Ihreamn of a (ihost Seer. Cf. also Part VI. ch. 1.
1 De Jtundi Sens, et Int.
, J 6: dantur per iptam naluram intellect in. Cf. | 8, aJao the corollary to f 8.
466 The Enlightenment : Theoretical Questions. [Part V.
actione secundum perpetuus leges sensa sua coordinante [from the very action of the mind co-ordinating its sensations according to perpetual laws], and like the intellectual Forms they are recognised by attending to the mind's activity on occasion of experience, — the business of mathematics.
Another formulation was given to the principle of virtual innate- ness by Tetens. He wrote his essays on human nature and its development under the impression received from Kant's Inaugural Dissertation. He, too, declares that the " acts of thought " are the first original relation-thoughts (Verhctttnissgedanken) : we learn them by applying them when we think; and thus they prove themselves to be the natural laws of thought. The universal prin ciples which lie at the basis of all philosophical knowledge are, accordingly, " subjective necessities " in which the essential nature of the thinking soul itself comes to consciousness.
§ 34. Knowledge of the Outer World.
The background of all these theories is their epistemological pur
This, however, assumes from the beginning a somewhat narrower place under the presupposition of the naive realism which became attached to the Cartesian metaphysics. The principle of the cogito ergo sum made the self-knowledge of the mind's nature appear as the original certainty, as that which was self-evident and immediately free from doubt ; but the greater the difference in kind which was conceived to exist between the world of consciousness and that of space and bodies, the greater the difficulties that pre sented themselves with reference to the possibility of knowing this latter world. This fact was taught at once by the metaphysical development immediately after Descartes (cf. § 31), and the same was now repeated in the most various forms in connection with the translation of these same thoughts into the language of empirical psychology and sensualism.
There is thus in the epistemology of modern philosophy from its beginning a superiority attributed to inner experience, by virtue of which knowledge of the outer world becomes problematical. In this an after- working of the Terminism, with which the Middle Ages had ended, asserts itself throughout the whole extent of modern thought as a determining mode of view : the heterogeneity of the outer and inner worlds gives the mind a proud feeling of a substantial quality peculiar to itself as contrasted with things, but at the same time a certain degree of uncertainty and doubtfulness in orienting itself in this world which is to it strange and foreign. In this way
pose.
Chap. 1, § 34. ] Knowledge of the Outer World : Locke. 467
the very statement of the fundamental problem in the philosophy of the Enlightenment shows itself to be an echo of that deepening of the mind within itself, that placing of consciousness upon an inde pendent basis over against the outer world, with which the ancient philosophy ended its course. In this was rooted the power of the Augustinian spirit over modern philosophy.
1. The preponderance of the inner experience asserts itself very strongly also with Locke, although in principle he placed sensation and reflection upon an equality psychologically, and in his genetic theory even made the latter dependent upon the former. But in assigning the epistemological values this relation is at once reversed in the spirit of the Cartesian principles. For the dualism of finite substances wjiich the great French metaphysician had propounded is quietly introduced by Locke in conjunction with the dualism of the sources of experience : sensation is designed to furnish knowledge of the corporeal outer world, reflection to give knowledge of the activities of the mind itself: and in this consideration it is naturally found that the latter is much more suited to its task than the former. Our knowledge of our own states is intuitive and the most certain of all ; and with a knowledge of our states we are at the same time perfectly and undoubtedly sure of our own existence also. Locke presents this doctrine of the certainty of knowledge of self with an almost verbal adherence to Descartes. ' With reference to our knowledge of the corporeal world, on the other hand, his attitude is much more reserved Such a knowledge is possible oi. 'y through sensation ; and although it still deserves the name knowledge, it yet lacks complete certainty and adequacy. Primarily, it is only the presence of the idea in the mind that is intuitively certain ; that a thing corresponds to the idea is not intuitively certain, and demon stration can at most teach that there is a thing there, but can predicate nothing concerning this thing.
To be sure, Locke is not at all in agreement with himself on this point. In connection with his theory of the ideas of sensation, he adopts the doctrine of the intellectual nature of the sense qualities quite in the form worked out by Descartes (cf. § 31, 2), designates them happily by the distinction of primary and secondary qualities, adds, as tertiary qualities, such powers as express the relation of one body to another, declares primary qualities to be those which really belong to bodies in themselves, and reckons, also, impenetrability in this class, in addition to those assigned to it by Descartes. As compared with the doctrine of Hobbes, this is in its essence a
> Kt$at IV. A, 3.
468 The Enlightenment : Theoretical Question*. [Part V.
decided relapse into the mode of thought of Democritus and Epicurus, as is shown, also, in the fact that Locke follows the theory of images in tracing stimulations • to the affection of the nerves by minute particles streaming out from objects. 1 On the whole, there fore, the fundamental Cartesian basis of mathematical knowledge of Nature is here reaffirmed, and even more widely extended.
But Locke's decision in connection with his analysis of the idea of substance has an entirely different purport. Like Occam, he distinguishes from intuitive knowledge and knowledge given by sensation, demonstrative knowledge: this has to do, not with the relation of ideas to the outer world, but with the relation of ideas to one another. In its value as knowledge it stands after the intui tive, but superior to the sensitive. 5 Demonstrative thinking is then conceived of entirely terministically, something as in the case of Hobbes, as a reckoning with concept signs. The necessity attach ing to the demonstration holds only within the world of ideas ; it concerns, as one class, general or abstract ideas to which no proper reality corresponds in natura rerum. If ideas are once present, judgments may be formed concerning the relations which exist between them, quite apart from any reference to the things them selves; and it is with such judgments alone that demonstrative knowledge has to do. Such "complex" ideas are thought-things, which, after they have been fixed by definition, can enter into the union with others determined in each case by the respective con tents, without thereby acquiring any relation to the outside world. Among these modes of union, that which is expressed by the idea of substance (the category of inherence) is conspicuous in an especial manner. For all other contents and relations can be thought only as belonging to some substance. This relation, therefore, has Reality, — the idea of substance according to Locke's expression, ectypal, — but only in the sense that we are forced to assume real substrate for the modes given in particular ideas, without being able to make any assertion as to what this substrate itself is. Substance is the supporter, itself unknown, of known qualities, which we have occa sion to assume belong together.
This view that substances are unknowable does not, indeed, hinder Locke from taking in hand at another passage,8 in an entirely Cartesian fashion, a division of all substances into " cogitative and incogitative. " On the other hand, he applies the view to his treat-
Essay, II. IT. Cf. also B. Rlittenauer, Zur VorgescMchte des Idealism*! und Kriticismus (Freiburg, 1882), and Geil, op. cit. , pp. 66 ft".
lb. IV. 2.
»Ib. II. 23,20; IV. 10. 9.
»1
8, 7
a
is,
Chap. 1, § 34. ] Knowledge of the Order World : Berkeley . 469
roent of the cogito ergo sum. This principle he carries over entirely from the metaphysical realm into that of empirical psychology. . . Self-certainty is for him thafr^jftne " internal sense " ; intuition in this case refers only to our states and activities, not to our essence ; it shows us, indeed, immediately and without doubt, that we are, but not what we are. The question a^ to the substance of the soul (and accordingly the question als»> As torts relation to the body) is as incapable of an answer as the question as to the " what" of any substance whatever.
Nevertheless, Locke holds it to be possible to gain a demonstrative certainty of the existence of Ood. For this purpose he adopts the first of the Cartesian proofs (cf. § 30, 5) in a somewhat modified form, and adds the ordinary cosmological argument An infinite, eternal, and perfect being must be thought, an ultimate cause of finite substances of which man intuitively knows himself to be one.
So manifold and full of contradictions are the motifs which cross in Locke's doctrine of knowledge. The exposition, apparently so easy and transparent, to which he diluted Cartesianism, glides over and away from the eddies which come up out of the dark depths of its historical presuppositions. But as the ambiguous, indeterminate nature of his psychology unfolded itself in the antithesis in the fol lowing developments, so, too, this episteinological metaphysics offered points of departure for the most varied transformations.
2. The very first of these shows an audacious energy of one-sided- ness in contrast with the indecisiveness of Locke. Berkeley brought the ascendeucy of inner experience to complete dominance by putting an end to the wavering position which Locke had taken upon the question as to the knowledge of bodies. This he did with the aid of his extreme Nominalism and with a return to the doctrines of Hobbes. He demolished the conception of corporeal substance. Ac cording to the distinction of primary and secondary qualities, it was held that a part of that complex of ideas which perception presents us as a body should be separated out, and another part retained as alone real; but this distinction, as Hobbes had already taught (cf. f 31, 2), is in the nature of the case erroneous. The "mathe matical " qualities of ladies are as truly ideas within us as the sense qualities, and Berkeley had demonstrated exactly this point with analogous arguments in his Theory of Vi»ion. He attacks the warrant of the distinction of Descartes (and of Democritus). But while, according to this view, all qualities of bodies without excep
tion are ideas in us, Locke has retained as their real supporter a superfluous unknowable "substance " ; in a similar way others speak of matter as the substrate of sensible qualities.
470 The Enlightenment : Theoretical Questions. [Part V.
But in all these cases, says Berkeley, it is demanded of us to regard an abstraction as the only actual reality. Abstract ideas, however, do not exist, — they do not exist even in the mind, to say nothing of existing in natura rerum. Locke was then quite right in saying that no one could know this "substance ": no one can even think it; it is a fiction of the schools. For the naive consciousness, for "common sense," whose cause Berkeley professes to maintain against the artificial subtlety of philosophers, bodies are just exactly what is perceived, no more and no less ; it is only the philosophers who 3eek for something else behind what is perceived, — something mysterious, abstract, of which they themselves cannot say what it is. For the unperverted mind, body is what one sees, touches, tastes, smells, and hears : its esse is percipi.
Body is then nothing but a complex of ideas. If we abstract from a cherry all the qualities which can be perceived through any of the senses, what is left ? Nothing. The idealism which sees in a body nothing farther than a bundle of ideas is the view of the common man ; it should be that of philosophers also. Bodies possess no other reality than that of being perceived. It is false to suppose that there is in addition to this a substance inherent within them, which "appears" in their qualities. They are nothing but the sum of these qualities.
In reply to the question that lies close at hand, in what the differ ence consists between the " real " or actual body and that which is only imagined or dreamed of, if all bodies are only perceived, Berkeley answers with a spiritualistic metaphysics. The ideas which constitute the existence of the outer world are activities of spirits. Of the two Cartesian worlds only one has substantial existence ; only the res cogitantes are real substances, the res extensa are their ideas. But to finite spirits the ideas are given, and the origin of all ideas is to be sought only in the infinite Spirit, in God. The reality of bodies consists, therefore, in this, that their ideas are
communicated by God to finite spirits, and the order of succession in which God habitually does this we call laws of Nature. Hence Bishop Berkeley finds no metaphysical difficulty in supposing that God under certain circumstances departs from the usual order for some especial end, and in this case man speaks of miracles. Ou the other hand, a body is unreal which is presented only in the indi vidual mind according to the mechanism of memory or imagination, and without being at the same time communicated to the mind by God. And finally, since the actual corporeal world is thus changed into a system of ideas willed by God, the purposiveness which its arrangement and the order of its changes exhibit gives rise to no further oroblem.
Chap. 1, § 34. ] Knowledge of the Outer World : Collier. 471
The parallelism between this inference from Locke and that which Malebranche had drawn from Descartes is unmistakable ; and Malebranche and Berkeley are also at one in holding that God alone is the active force in the world, and that no individual thing is efficiently operative (cf. § 31, 8). It is extremely interesting to see how the extreme Realism of the Frenchman and the extreme Nominalism of the Englishman amount to the same thing. The grounds on which the views are based could not be more different : the result is the same. For what still separated the two could be easily removed out of the way. This was proved by a contemporary and countryman of Berkeley's, Arthur Collier (1680-1732) in his interesting treatise Clavis Universalis. 1 Malebranche,1 indeed, as a Cartesian, had not directly demurred to the reality of the corporeal world, but had held that we could understand the knowledge of this world by man, only on the hypothesis that the ideas of bodies in God are the common original, in accordance with which God pro duces, on the one hand, the actual bodies, and, on the other, the
ideas of these bodies in finite minds. Collier showed now that in this theory the reality of the corporeal world played a completely superfluous rSle : since no actual relation between the corporeal world and human ideas is assumed, the value of human ideas for knowledge remains quite the same if we posit only an ideal cor poreal world in God, and regard this as the real object of human knowledge.
The idealism, which proceeded in this way from the cogito ergo turn along several paths, was attended by still another paradox as a by-product, which is occasionally mentioned in the literature of the eighteenth century without any definite name or form. Each individual mind has certain, intuitive knowledge only of itself and of its states, nor does it know anything of other minds
through ideas, which refer primarily to bodies and by an argument from analogy are interpreted to indicate minds. If, however, the whole corporeal world is only an idea in the mind, every individual is ultimately certain only of his own existence ; the reality of all else, all other minds not excluded, is problematical and cannot be demonstrated. This doctrine was at that time designated as Egoism, now it is usually called Solipsism. It is a metaphysical
1 The alternative title of the book reads, A Xev> Inquiry after Trvth. being m Demonstration of the Son-Existence or Impossibility of an External World
It wwi edited together with Berkeley's treat in* in the (iennan •• Collection of the Principal Writings which deny the Reality of their oxen Body ( . '. ') and of the tehole Corporeal World," by Kechenbach (Koitock. 1766).
* Wh<>«e doctrine had become known in England by the agency especially of John Sorris (Essai (Tun Theorie du Monde Idial, Lond. 1704).
(Lond. 1123).
except
472 Tlit EnliyhteniHtnt : Theoretical Questions. [Part V
sport which must be left to the taste of the individual; for the solipsist refutes himself by beginning to prove his doctrine to others.
Thus, following in the train of the Meditations, in which Descartes recognised self-consciousness as the rescuing rock in the sea of doubt, the result was finally reached which Kant later characterised as a scandal to philosophy ; namely, that a proof was demanded for the reality of the outer world, and none adequate could be found. The French materialists declared that Berkeley's doctrine was an insane delusion, but was irrefutable.
3. The transformation of Locke's doctrine by Berkeley leads farther in a direct line to Hume's theory of knowledge. To the nominalistic denial of abstract ideas the penetrative and profound Scot attached his distinction of all intellectual functions into im pressions, and ideas which are copies of impressions ; and coincident with his distinction is that of intuitive and demonstrative knowl edge. Each kind of knowledge has its own kind of certainty. Intuitive knowledge consists simply in the affirmation of actually present impressions. What impressions I have, I can declare with absolute certainty. I can make no mistake in this, in so far as I keep within the bounds of simply stating that I have a perception possessing this or that simple or complex content, without adding any conceptions which would put any interpretation upon this content.
As among the most important of these impressions which have immediate intuitive certainty Hume reckons the relations in space and time of the contents of sensation, — the fixing of the co-exist ence or succession of elementary impressions. The spatial order in which the contents of perception present themselves is undoubtedly given immediately with the contents themselves, and we likewise possess a sure impression as to whether the different contents are perceived at the same time or in succession. Contiguity in space and time is therefore intuitively given together with the impres sions, and of these facts the human mind possesses a knowledge which is perfectly certain and in nowise to be questioned. Only,
in characterising Hume's doctrine, it must not be forgotten that this absolutely certain matter-of-fact quality, which belongs to impressions, is solely that of their presence as mental states. In this meaning and restriction intuitive knowledge embraces not only the facts of inner experience, but also those of outer experience, but at the price of recognising that the latter are properly only species of the former, — a knowledge, that of mental states.
Contiguity in space and time however, but the most elementary
is,
is,
Chap. J, $ 34. ] Knowledge of the Outer World: Hume. 478
form of association between perceptions ; besides this Hume reckons two other laws, those of resemblance (or contrast, respectively) and causality. As regards the former of these two forms of relation, we hare a clear and distinct impression of the likeness or unlike- ness of sensations, and of the different degrees of these ; it consists in the knowledge of the degree of resemblance in our own (sensi tive) action, and belongs therefore to the impressions of the inner sense, which Locke called reflection. On this is based, consequently, a demonstrative knowledge of complete certainty ; it concerns the forms of that comparison between magnitudes which we perform upon the given contents of our ideas, and is nothing but an analysis of the regularity with which this takes place. This demonstrative science is mathematics ; it develops the laws of equality and propor tion with reference to numbers and space, and Hume is inclined to concede a still higher epistemological value to arithmetic than to geometry. 1
4. But mathematics is also the sole demonstrative science; and is that just because it relates to nothing else than the possible rela tions between contents of ideas, and asserts nothing whatever as to any relation of these to a real world. In this way the terministic principle of Hobbes (cf. § 30, 3) is in complete control with Hume, but the latter proceeds still more consistently with his limitation of this theory to pure mathematics. Fo»Hume declares that no asser tion respecting the external world is capable of demonstration ; all our knowledge is limited to the ascertaining and verifying of
impressions, other.
and to the relations of these mental states to each
Hence it seems to Hume an unauthorised trenching of thought beyond its own territory, when the resemblance between ideas is interpreted as meaning metaphysical identity ; this is the case in
every employment of the conception of substance. Whence is this conception ? It is not perceived, it is not found as a content either in particular sensations or in their relations; substance is the unknown, indescribable support of the known contents of ideas. Whence this idea for which no impression is to be found in the whole circuit of sensations as its necessary original ? Its origin is to be sought in reflection. It is the copy of a frequei tly repeated
conjunction of ideas. By the repeated being together of impres sions, by the custom of the like ideational process there arises by virtue of the law of association of ideas the necessity of the idea of their co-existence, and the feeling of this associative necessity of the
' Treat. I. 2, 1 ; I. 3, 1.
474 The Enlightenment : Theoretical Questions. [Part V.
ideational process is thought as a real belonging together of the elements of association, i. e. as substance.
The thought-form of inherence is thus psychologically explained, and at the same time epistemologically rejected; nothing corre sponds to it further than the feeling of a likeness in the ideational conjunction ; and since we can never know anything of existence except by immediate sense-perception, the Reality of the idea of substance is incapable of proof. It is clear that Hume thus makes Berkeley's doctrine his own, so far as it concerns corporeal things.
But Berkeley had but half done his work upon the idea of substance. He found that bodies are only complexes of sensations ; that their being is identical with their being perceived ; that there is no sense or meaning in hypostatising their belonging together, as an unknown substance : but he let the psychical substances, spirits, the res cogi- tantes, stand ; he regarded them as the supports or agents in which all these ideational activities inhere. Hume's argument applies to this latter class also. What Berkeley showed of the cherry is true also of the " self. " Inner perception, also (such was the form which it had actually taken on already with Locke; cf. above, No. 1), shows only activities, states, qualities. Take these away, and noth ing remains of Descartes' res cogiians either : only the " custom " of constant conjunction of ideas in imagination is at the basis of the conception of a "mind"; the self is only a " bundle of perceptions. " '
The same consideration holds also, mxttatis mutandis, for causality, that form under which the necessary connection between contents of ideas is usually thought : but this is neither intuitively nor de monstratively certain. The relation of cause and effect is not per ceived ; all that we can perceive by the senses is the relation in time, according to which one regularly follows the other. If, now, thought interprets this sequence into a consequence, this post hoc into a propter hoc,1 this too has no basis in the content of the ideas causally related to each other. From a "cause" it is not possible to deduce logically its " effect " ; the idea of an effect does not con tain within it that of its cause. It is not possible to understand the causal relation analytically. ' Its explanation is, according to
1 Treat.
