Condillac’s philosophical writings may be studied from three points of view. Like Locke, he begins with a polemic against innate ideas and abstract systems. This· takes up a large part of the Essai sur l’ Origine and almost the whole of the Traité des Systèmes. In the Logique and the Art de Raisonner he expounds and illustrates the analytic method, which he regards as the only true method of science, and which is further illustrated in La Langue des Calculs. L’Art de Penser consists largely of quotations from the Essai sur l'Origine. In the Traité des Sensations, Condillac applies his analytic method to the solution of the psychological problem of the origin of our ideas and the formation of the mental faculties. It cannot be said that he strictly confines himself to the questions-here assigned to his different works. His inveterate antipathy to innate ideas and abstract systems, his favour for analysis, and his peculiar psychological doctrines appear more or less in them all.

Condillac’s main attacks are directed against the innate ideas of Descartes, Μ al eb ran che’s theory of the mental faculties, the monadology of Leibnitz, and the first part of Spinoza’s Ethisc. He thinks that innate ideas were assumed because men had not sagacity and penetration enough to go back to the origin of ideas and trace their genesis, and he finds the consequences of the system to be the multiplication of abstract principles, and a pretence of accounting for everything by the use of abstract terms. Malebranche is justly censured for giving comparisons-instead of reasons in his explanation of understanding and will. In criticizing the monadology of Leibnitz, Condillac exaggerates the vagueness and inadequacy of the ideas furnished by the reason, and the clearness of those of the senses. He cannot comprehend how each monad represents the universe in virtue of its relations toit. But may there not be a sense in which the ultimate particular in the infinitude of its relations is a mirror of the universe? Condillac regarded Spinozism as the best example of an abstract system, and criticized in detail the first part of the Ethik, in order to show that Spinoza failed both as to clearness of ideas and precision in the use of signs—two essential conditions of the geometrical method which he adopted. Condillac divides the various philosophical systems into three classes :—(1) abstract systems which rest only on abstract principles; (2) hypotheses, or systems grounded on mere suppositions; (3)one true system, that of Locke, which is evolved from the facts of experience. The first he treats with unmitigated scorn; the second he admits under limitations; the third alone he regards as the true method of philosophy.

An act of reasoning, according to Condillac, consists in detecting a judgment which is implicitly contained in another. Sometimes, to go from the known to the unknown, it is necessary to pass through a series of intermediate judgments, each of which is contained in the one preceding. For example, the judgment that mercury will risa to a certain height in the barometer is contained implicitly in the judgment that air has weight; but we require a seriea of intermediate judgments to see that the former is a consequence of the latter. The evidential force of a reasoning: thus consists in the identity between the judgments of which it consists. They are the same; only the expression changes. Such a principle could not be made to cover all the varieties of reasoning. Accordingly Condillac tries to reduce them all to the mathematical form. To reason is to calculate, and to calculate is to reason; aud reasoning, like calculation, comes to be a merely mechanical operation. Condillac rejects the common explanation of reasoning, that it is a comparison of two terms with a common third to find their relation to each other. He sees no need for a middle term. The force of the demonstration, he thinks, lies in the identity of the two extremes, which is made evident by decomposing them. Of the syllogism he says that it makes reasoning consist in the form of expression rather than in the development of the ideas, and that most of its rules have been framed with a view to concluding from the genus to the species, whereas thought sets out from particulars.

Regarding the criterion of truth, he attacks the Cartesian test of truth, and proposes instead of it his own criterion of identity. In the Essai sur Γ Origine des Connaissances he brings two objections against Descartes :—(1) the methodic doubt is insufficient and even useless, because, while calling our ideas in question, it leaves them in all their indeterminateness; (2) it is impracticable, for we cannot doubt about the relations which exist between familiar and determinate ideas like those of numbers. Of the Cartesian criterion of truth, “all that is contained in the clear and distinct idea of a thing may be affirmed of it with truth,” Condillac says that it is both useless and dangerous, and should not have been extended to cases different from the one which gave it birth. For Condillac the sign of truth is identity. The evidence of a proposition is in the identity of the two terms. The evidence of a reasoning is in the identity of the successive propositions. No definition, however, is given of identity. It is said to be recognized when a proposition can be expressed in terms equivalent to these,—“the same is the same.” But •Condillac draws a distinction between identical propositions that are frivolous and those which are instructive, and explains the latter to be those in which the terms are identical in thought, but different in expression. Condillac held that three kinds of evidence are needed to arrive at certainty—the evidence of fact, the evidence of feeling, and the evidence of reason. The evidence of fact informs us of the relations which bodies have to us; it can have no other object. The evidence of feeling enables us to distinguish what passes in us, the modes or states of the mind. Some good remarks are made in chapter iii., part i., of EArt de Penser, on the attentive observation of consciousness. The evidence of reason is discussed in the first three chapters of the first part of If Art de Raisonner. There Condillac merely formulates the principle of identity, and cites as examples the geometrical theorems which his pupil will require, that he may understand the rest of the work.

Condillac was of opinion that one method of analysis is common to all the sciences. Our cognitions ought to form a system in which all is strictly connected together. Every series of facts should be reduced to an initial fact, of which the others are only transformations. Identity is a rule of method as well as a criterion of certainty; and analogy completes the primary lessons which are given us by nature. Condillac takes as his model the method of mathematics, and reiterates through his logical writings that we must take nature for our guide. On the relation of analysis to language he held that there is an innate language, although there are no innate ideas. This language produces a kind of analysis, since it is necessary for the communication of our ideas to analyze and express in succession what is simultaneous in thought. Analysis then reacts on language and improves it. Finally, perfection of language leads to perfection of analysis, and science is only a langue bien faite.

The method of invention is discussed chiefly in the Essai sur V Origine des Connaissances and in the Langue des Calculs. In the former, Condillac bids us take the simple ideas furnished by sensation and reflection, form different collections of them, which in their turn will produce others, aud give distinct names to these different collections. In the Langue des Calculs the idea of analogy is .developed. This is not the analogy set forth in the Art de Raisonner, which consists only in forming more or less probable conjectures about the unknown from the known. The analogy of the Logique and the Langue des Calculs is that which creates and regulates languages, which causes us to invent different systems of signs and submit them to uniform rules.

Reasoning cannot have the purely subjective character which Condillac’s theory assigns to it. It takes its departure from the idea, which is objective, and therefore establishes a real relation between the mind and its object. On the question of the need for a middle term it is not enough to decompose the two ideas. The two decompositions must meet at a point, and that is the middle term. Laromiguière preserves the intermediate ideas, which he thinks are found by analysis of the extremes. So they are. But it has been urged that there is a twofold analysis—of the species into its genera and of the genus into its species —whereby the middle term is found. Condillac is inconsistent with himself in his criticism of Descartes. His first objection to the methodic doubt is based on the opinion that all our errors proceed from the indeterminate character of language, and that the use of definite signs is the only security against error. But he believes that analysis makes language; and the methodic doubt is a kind of analysis, for it remounts to the primary truths. His second objection, that we cannot doubt about mathematical relations, is invalidated by his own statement that mathematics are only part of metaphysics. Condillac is right in saying that the Cartesian criterion of truth lacks a theory of ideas and of their origin. But it is not to be condemned as useless because it is incomplete. Condillac was led away by the supposed need for a sign whereby to recognize truth. As Hegel would have put it, he refused to go into the water until he could swim. But it would be as difficult to determine the value of the sign as that of the truth itself. Some such criterion as identity is the only resource of empiricism. But if the notion of identity is derived from experience, it cannot give certainty. If, that it may serve as the basis of logic, it is regarded as necessary, then empiricism cannot reconcile it with its psychology. Laromiguière tries to get over the difficulty of accounting for progress in a system based on the notion of identity, by drawing a distinction between partial identity and total identity, and saying that the former alone should be admitted. But what is partial identity 1 Condillac himself takes refuge in extreme idealism. Truth, he says, considered in itself and in the divine intelligence, is one and identical. But he had himself laid down the rule to limit our consideration to the condition of human knowledge, and of course he had no idea of developing thought as such from its primal unit by a dialectic process after the manner of Hegel. As to the three kinds of evidence, Condillac in reality reduces the evidence of fact to that of feeling aud that of reason. His numerous contradictions are largely due to his attempts to defend the authority of the senses, while he accepts the idealistic theory of external perception. The objections to identity as a criterion of truth apply as well to Condillac’s statement of the evidence of reason. And if the three kinds of evidence are inadequate taken separately, they cannot suffice when combined. Condillac rightly insisted that there is one fundamental method for all the sciences; but he nowhere reconciles this unity of method with the variety of form which it assumes as applied to different objects. By demanding at the outset the initial fact, of which all the others are to be shown to be transformations, he virtually quits the safe road of experience. He errs, too, in thinking that the method of mathematics is applicable to all the sciences. His oft-repeated advice to follow nature would have been advantageously accompanied by a clearer explanation of what nature is. One thing which he certainly excludes from it is the mind viewed as the seat of intellectual principles. Condillac’s analysis combines what are generally regarded as the two distinct processes of analysis and synthesis. Synthesis he conceives to be that method which starts from abstract principles, and accordingly he treats it with supreme disdain. But while banishing the name he retains the thing, and insists that no analysis is complete without a process of recomposition.

The logic of Condillac finds its most important application in psychology. In the Essai sur l , 0rigine des Connaissances he starts from sensation as the primitive fact, and seeks to show that all the ideas and operations of the mind are only transformations of it. He neglected, however, to make sure of his way back to the primitive fact of sensation, before using it as his starting point. Under the influence of Locke, he simply assumed it, and applied his ingenuity to derive from it all the ideas and operations of the mind. Throughout the Essai sur V Origine he confounds sensation with perception in a way that vitiates his whole argument. At the outset he affirms that sensations are ideas, because representative of objects. It is difficult to understand in what sense he uses such language. For a long time it was supposed that he regarded the pure sensation as the primary element of consciousness; but his more recent followers have adopted a different interpretation. They try to make out that his meaning was that in the simplest state of consciousness the whole mind is to be found, equipped with all its so-called faculties. Condillac found an opinion prevailing that the mind is partitioned off, as it were, into a variety of different faculties, each having its separate function, which it discharges independently of the others. It was against this opinion, they say, that he contended. He maintained that the mind is not a congeries of faculties, but is one and indivisible, and appears in all its forms of activity in the simplest state of consciousness. This opinion is difficult to reconcile with his avowed purpose, to which he adheres throughout all his psychological treatises, of tracing the genesis of the faculties; for sensation would then not be a primitive fact, from which all the later furniture of the mind is derived by a process of transformation. There would, in fact, be no generation of the faculties, for all would be given in the rudimentary consciousness, and any reasoned account of their relations to each other would need to refer to something anterior to the individual consciousness. Probably the more correct view to take of Condillac’s psychology is that when he tried to deal with sensation, pure and simple, he found it impossible to do so, and was compelled to invest the mere sensation with all the ideas of reason, that it might do duty in his system. No doubt either interpretation would save Condillac’s consistency with his great principle of identity. The sameness of the elementary sensation with the higher faculties and ideas is secured, whether the faculty is degraded to the level of the sensation, or the sensation is raised to the level of the faculty. And there is much in Condillac to countenance either view. But it is probable that if he had been willing to concede that the mind is all in the primary sensation, in the sense in which his later followers understand him, he would have felt the necessity of exhibiting the relations of the different mental onerations, which in such case would be moments of the sensation, anterior to the sensation, instead of subsequent to it, in terms of the relations of different sensations to each other. The opening sentences of the Traité des Sensations show that Condillac was aware of the difficulties attending the study of our rudimentary consciousness on the presuppositions of sensationalism. If the mind at birth was a tabula rasa, there can be no traces left of our primary state. It is in vain therefore to interrogate our consciousness to learn what it was then. To show how all proceeds from sensation, we must consider our senses separately. As Condillac could not do this by examining his own consciousness, he devised the experiment of the statue. It is supposed to be possessed of a mind destitute at first of every sort of ideas, and only to have the use of its senses at the pleasure of the experimenter, who opens them at his choice to their appropriate impressions. A beginning is made with the sense of smell, because it seems to contribute least to our knowledge. The other senses are successively experimented on, singly and in groups, and at last the statue is found to have become an animal able to preserve itself. Condillac claims to have stripped man for the first time of all his habits. Feeling is observed at its birth, and proof is given of how we acquire the use of our faculties. The principle of their development is found in the various degrees of pleasure and pain attaching to our sensations; for none of them are indifferent absolutely. The contrast between pleasure and pain impels us to court some sensations and flee others. A sense of need is produced by the want of an object judged necessary for happiness. Needs beget desires; old needs repeated and new ones formed are the ground of the development of our knowledge and our faculties. The outcome of Condillac’s psychology is given in briefest form in chapters vii. and viii. of the Logique. Laromiguière corrected Condillac by substituting attention for sensation as the principle of the active half of the mental phenomena. Cousin pointed out that attention is a voluntary act. He showed the essential difference between desire and will, as also between sensation and desire, and remarked that the organic impression must not be confounded with the sensation. If the sensation is the condition of the exercise of the faculties, still it is not the principle of any.

Condillac defines personality to be a collection of sensations plus the ability to say “me.” But this plus is of vast importance. How comes it that this particular collection of sensations can say “me ì” Because, answers Condillac, it is a collection of present and remembered sensations. But whether does the statue say “me” because it can remember its sensations, or remember its sensations because it can say “me ”î Is not all that is involved in saying me already involved in memory, so that his answer merely repeats the fact which it professes to explain î Condillac thought so in his first stage, as he then found the feeling of one’s own existence to be an essential element of reminiscence. Then, indeed, reminiscence was distinguished by him from memory, but only in an artificial w ay. A collection of sensations is a less correct account of personality than the synthetic unity of Kant. What renders the collection possible! For Condillac its essential condition, a unifying principle, is wanting. That cannot be found in sensation. It is a condition of the ordering of sensations, and is the all-important unit out of which a true philosophy of spirit must grow. Sensations cannot give an answer to the question what constitutes experience. Even Mill had to confess that it...