Category

Our knowledge of Hindu philosophy, and of the relations in which it may have stood to Greek speculation, scarcely enables us to give decisive answers to various questions that naturally arise on observation of their many resemblances (see Hindu philosophy. an article by Richard Garbe in Monist, iv. 176-193). Yet the similarity between the two is so striking that, if not historically connected, they must at least be regarded as expressions of similar philosophic needs. The Hindu classification to which we specially refer is that of Kanada, who lays down six categories, or classes of existence, a seventh being generally added by the commentators. The term employed is Padārtha, meaning “signification of a word.” This is in entire harmony with the Aristotelian doctrine, the categories of which may with truth be described as significations of simple terms, τὰ κατὰ μηδεμίαν συηπλοκὴν λεγόμενα. The six categories of Kanada are Substance, Quality, Action, Genus, Individuality, and Concretion or Co-inherence. To these is added Non-Existence, Privation or Negation. Substance is the permanent substance in which Qualities exist. Action, belonging to or inhering in substances, is that which produces change, Genus belongs to substance, qualities and actions; there are higher and lower genera. Individuality, found only in substance, is that by which a thing is self-existent and marked off from others. Concretion or Co-inherence denotes inseparable or necessary connection, such as that between substance and quality. Under these six classes, γένη τοῦ ὄντος, Kanada then proceeds to range the facts of the universe.1

Within Greek philosophy itself there were foreshadowings of the Aristotelian doctrine, but nothing so important as to warrant the conclusion that Aristotle was directly influenced by it. Doubtless the One and Many, Being and Non-Being, of the Greek philosophy Eleatic dialectic, with their subordinate oppositions, may be called categories, but they are not so in the Aristotelian sense, and have little or nothing in common with the later system. Their starting-point and results are wholly diverse. Nor does it appear necessary to do more than mention the Pythagorean table of principles, the number of which is supposed to have given rise to the decuple arrangement adopted by Aristotle. The two classifications have nothing in common; no term in the one list appears in the other; and there is absolutely nothing in the Pythagorean principles which could have led to the theory of the categories.2

One naturally turns to Plato when endeavouring to discover the genesis of any Aristotelian doctrine, and undoubtedly there are in the Platonic writings many detached discussions in which the matter of the categories is touched upon. Special Plato. terms also are anticipated at various times, e.g. ποιότης in the Theaetetus, ποιεῖν and πάσχειν in the Gorgias, and πρός τι in the Sophist.3 But there does not seem to be anything in Plato which one could say gave occasion directly and of itself to the Aristotelian doctrine; and even when we take a more comprehensive view of the Platonic system and inquire what in it corresponds to the widest definition of categories, say as ultimate elements of thought and existence, we receive no very definite answer. The Platonic dialectic never worked out into system, and only in two dialogues do we get anything like a list of ultimate or root-notions. In the Sophist, Being, Rest and Motion (τὸ ὄν αύτὸ καὶ στάσις καὶ κίνησις) are laid down as μέγιστα τῶν γενῶν.4 To these are presently added the Same and the Other (ταὐτὁν καὶ θάτερον), and out of the consideration of all five some light is cast upon the obscure notion of Non-Being (το μὴ ὄν). In the same dialogue (262 seq.) is found the important distinction of ὄνομα and ῥῆμα, noun and verb. The Philebus presents us with a totally distinct classification into four elements—the Infinite, the Finite, the Mixture or Unity of both and the Cause of this unity (τὸ ἄπειρον, τὸ πέρας, ἡ σύμμιξις, ἡ αίτία). It is at once apparent that, however these classifications are related to one another and to the Platonic system, they lie in a different field from that occupied by the Aristotelian categories, and can hardly be said to have anything in common with them.

The Aristotelian doctrine is most distinctly formulated in the short treatise Κατηγορίαι, which generally occupies the first place among the books of the Organon. The authenticity of the treatise was doubted in early times by some of the Aristotle. commentators, and the doubts have been revived by such scholars as L. Spengel and Carl Prantl. On the other hand, C.A. Brandis, H. Bonitz, and Ed. Zeller are of opinion that the tract is substantially Aristotle’s. The matter is hardly one that can be decided either pro or con with anything like certainty; but this is of little moment, for the doctrine of the categories, even of the ten categories, does not stand or fall with only one portion of Aristotle’s works.

It is surprising that there should yet be so much uncertainty as to the real significance of the categories, and that we should be in nearly complete ignorance as to the process of thought by which, Aristotle was led to the doctrine. On both points It is difficult to extract from the matter before us anything approaching a satisfactory solution. The terms employed to denote the categories have been scrutinized with the utmost care, but they give little help. The most important—κ. τοῦ ὄντος or τῆς οὐσίας, γένη τοῦ ὄντος or τῶν ὄντων, γένη simply, τὰ πρῶτα or τὰ κοινὰ πρῶτα, αἱ πτῶσεις, or αἱ διαιρέσεις—only indicate that the categories are general classes into which Being as such may be divided, that they are summa genera. The expressions γένη τῶν κατηγορίων and σχήματα τῶν κ., which are used frequently, seem to lead to another and somewhat different view. κατηγορία being taken to mean that which is predicated, γένη τῶν κ. would signify the most general classes of predicates, the framework into the divisions of which all predicates must come. To this interpretation there are objections. The categories must be carefully distinguished from predicables; in the scholastic phraseology the former refer to first intentions, the latter to second intentions, i.e. the one denote real, the other logical connexion. Further, the categories cannot without careful explanation be defined as predicates; they are this and something more. The most important category, οὐσία, in one of its aspects cannot be predicate at all.

In the Κατηγορίαι Aristotle prefixes to his enumeration a grammatico-logical disquisition on homonyms and synonyms, and on the elements of the proposition, i.e. subject and predicate. He draws attention to the fact that things are spoken of either in the connexion known as the proposition, e.g. “a man runs,” or apart from such connexion, e.g. “man” and “runs.” He then proceeds, “Of things spoken of apart from their connexion in a proposition (τῶν κατὰ μηδεμίαν συμπλοκὴν λεγομένων), each signifies either Substance (οὐσία), or Quantity (ποσόν), or Quality (ποιόν), or Relation (πρός τι,) or Where (i.e. Place, ποῦ), or When (i.e. Time, ποτέ), or Position (κεῖσθαι), or Possession (ἔχειν), or Action (ποιεῖν), or Passion (πάσχειν). οὐσία, the first category, is subdivided into πρώτη οὐσία or primary substance, which is defined to be τόδε τι, the singular thing in which properties inhere, and to which predicates are attached, and δεύτεραι οὐσίαι, genera or species which can be predicated of primary substances, and are therefore οὐσία. only in a secondary sense. Nevertheless, they too, after a certain fashion, signify the singular thing, τόδε τι” (K. p. 3 b 12, 13). It is this doctrine of πρώτη οὐσία that has raised doubts with regard to the authenticity of the Κατηγορίαι But the tenfold classification, which has also been captiously objected to, is given in an acknowledged writing of Aristotle’s (see Topica, i. 9, p. 103 b 20).5 At the same time it is at least remarkable that in two places where the enumeration seems intended to be complete (Met. p. 1017 a 25; An. Pos. i. 22, p. 83 a 21), only eight are mentioned, ἔχειν and κεῖσθαι being omitted. In other passages6 six, five, four, and three are given, frequently with some addition, such as καὶ αἱ ἄλλαι κ. It is also to be observed that, despite of this wavering, distinct intimations are given by Aristotle that he regarded his list as complete, and he uses phrases which would seem to indicate that the division had been exhaustively carried out. He admits certainly that some predicates which come under one category might be referred to another, but he declines to deduce all from one highest class, or to recognize any relation of subordination among the several classes.

The full import of the categories will never be adequately reached from the point of view taken up in the Κατηγορίαι, which bears all the marks of an early and preliminary study. For true understanding we must turn to the Metaphysics, where the doctrine is handled at large. The discussion of Being in that work starts with a distinction that at once gives us a clue. τὸ ὄν is spoken of in many ways; of these four are classified—τὸ ὄν κατὰ συμβεβηκός, τὸ ὄν ὼς ὰληθές, τὸ ὄν δυνάμει καὶ ἑνεργείᾳ, and τὸ ὄν κατὰ τὰ σχήματα τῶν κατηγορίων. It is evident from this that the categories can be regarded neither as purely logical nor as purely metaphysical elements. They indicate the general forms or ways in which Being can be predicated; they are determinations of Being regarded as an object of thought, and consequently as matter of speech. It becomes apparent also why the analysis of the categories starts from the singular thing, for it is the primary form under which all that is becomes object of knowledge, and the other categories modify or qualify this real individual. Πάντα δὲ τὰ γιγνόμενα ὑπό τέ τινος γίγνεται καὶ ἔκ τινος καὶ τὶ. Τὸ δὲ τὶ λέγω καθ᾽ ἑκάστην κατηγορίαν᾽ ἢ γὰρ τόδε ἢ ποσὸν ἢ ποιὸν ἢ ποῦ (Met. p. 1032 a 13-15).... The categories, therefore, are not logical forms, but real predicates; they are the general modes in which Being may be expressed. The definite thing, that which comes forward in the process from potentiality to full actuality, can only appear and be spoken of under forms of individuality, quality, quantity and so on. The nine later categories all denote entity in a certain imperfect fashion.

The categories then are not to be regarded as heads of predicates, the framework into which predicates can be thrown. They are real determinations of Being—allgemeine Bestimmtheiten, as Hegel calls them. They are not summa genera of existences, still less are they to be explained as a classification of namable things in general. The objections Mill has taken to the list are entirely irrelevant, and would only have significance if the categories were really—what they are not—an exhaustive division of concrete existences. Grote’s view (Aristotle, i. 108) that Aristotle drew up his list by examining Various popular propositions, and throwing the different predicates into genera, “according as they stood in different logical relation to the subject,” has no foundation. The relation of the predicate category to the subject is not entirely a logical one; it is a relation of real existence, and wants the essential marks of the prepositional form. The logical relations of τὸ ὂν are provided for otherwise than by the categories.

Aristotle has given no intimation of the course of thought by which he was led to his tenfold arrangement, and it seems hopeless to discover it. Trendelenburg in various essays has worked out the idea that the root of the matter is to be found in grammatical considerations, that the categories originated from investigations into grammatical functions, and that a correspondence will be found to obtain between categories and parts of speech. Thus, Substance corresponds to noun substantive, Quantity and Quality to the adjective, Relation partly to the comparative degree and perhaps to the preposition, When and Where to the adverbs of time and place. Action to the active, Passion to the passive of the verb, Position (κεῖσθαι) to the intransitive verb, ἔχειν to the peculiar Greek perfect. That there should be a very close correspondence between the categories and grammatical elements is by no means surprising; that the one were deduced from the other is both philosophically and historically improbable. Reference to the detailed criticisms of Trendelenburg by Ritter, Bonitz, and Zeller will be sufficient.

Aristotle has also left us in doubt on another point. Why should there be only ten categories? and why should these be the ten? Kant and Hegel, it is well known, signalize as the great defect in the Aristotelian categories the want of a principle, and yet some of Aristotle’s expressions would warrant the inference that he had a principle, and that he thought his arrangement exhaustive. The leading idea of all later attempts at reduction to unity of principle, the division into substance and accident, was undoubtedly not overlooked by Aristotle, and Fr. Brentano7 has collected with great diligence passages which indicate how the complete list might have been deduced from this primary distinction. His tabular arrangements (pp. 175, 177) are particularly deserving of attention. The results, however, are hardly beyond the reach of doubt.

There was no fundamental change in the doctrine of the categories from the time of Aristotle to that of Kant, and only two proposed reclassifications are of such importance as to require notice. The Stoics adopted a fivefold arrangement of Later Greek. highest classes, γενικώτατα. τὸ ὄν or τὶ, Being, or somewhat in general, was subdivided into ὑποκείμενα or subjects, ποιά or qualities in general, which give definiteness to the blank subject, πὼς ἔχοντα, modes which further determine the subject, and πὼς ἔχοντα, definite relative modes. These categories are so related that each involves the existence of one higher than itself, thus there cannot be a πρός τι πὼς ἔχον which does not rest upon or imply a πὼς ἔχον, but πὼς ἔχον is impossible without ποιόν, which only exists in ὑποκείμενον, a form or phase of τὸ ὄν.8

Plotinus, after a lengthy critique of Aristotle’s categories, sets out a twofold list. τὸ ἔν, κίνησις, στάσις, ταὐτότης, ἑτερότης are the primitive categories (πρῶτα γένη) of the intelligible sphere. οὐσία, πρός τι, ποιά, ποσόν, κίνησις are the categories of the sensible world. The return to the Platonic classification will not escape notice.

Modern philosophy, neglecting altogether the dry and tasteless treatment of the Aristotelian doctrine by scholastic writers, gave a new, a wider and deeper meaning to the categories. They now appear as ultimate or root notions, the metaphysical Modern philosophy. or thought elements, which give coherence and consistency to the material of knowledge, the necessary and universal relations which obtain among the particulars of experience. There was thus to some extent a return to Platonism, but in reality, as might easily be shown, the new interpretation was, with due allowance for difference in point of view, in strict harmony with the true doctrine of Aristotle. The modern theory dates in particular from the time of Kant, who may be said to have reintroduced the term into philosophy. Naturally there are some anticipations in earlier thinkers. The Substance, Attribute and Mode of Cartesianism can hardly be classed among the categories; nor does Leibnitz’s chance suggestion of a fivefold arrangement into Substance, Quantity, Quality, Action and Passion, and Relations, demand any particular notice. Locke, too, has a classification into Substances, Modes and Relations, but in it he has manifestly no intention of drawing up a table of categories. What in his system corresponds most nearly to the modern view of these elements is the division of kinds of real predication. In all judgments of knowledge we predicate either (1) Identity or Diversity, (2) Relation, (3) Co-existence, or necessary connexion, or (4) Real existence. From this the transition was easy to Hume’s important classification of philosophical relations into those of Resemblance, Identity, Time and Place, Quantity or Number, Quality, Contrariety, Cause and Effect.

These attempts at an exhaustive distribution of the necessary relations of all objects of knowledge indicate the direction taken by modern thought, before it received its complete expression from Kant.

The doctrine of the categories is the very kernel of the Kantian system, and, through it, of later German philosophy. To explain it fully would be to write the history of that philosophy. The categories are called by Kant Root-notions of the Kant. Understanding (Stammbegriffe des Verstandes), and are briefly the specific forms of the a priori or formal element in rational cognition. It is this distinction of matter and form in knowledge that marks off the Kantian from the Aristotelian doctrine. To Kant knowledge was only possible as the synthesis of the material or a posteriori with the formal or a priori. The material to which a priori forms of the understanding were applied was the sensuous content of the pure intuitions, Time and Space. This content could not be known by sense, but only by intellectual function. But the understanding in the process of knowledge makes use of the universal form of synthesis, the judgment; intellectual function is essentially of the nature of judgment or the reduction of a manifold to unity through a conception. The specific or type forms of such function will, therefore, be expressed in judgments; and a complete classification of the forms of judgments is the key by which one may hope to discover the system of categories. Such a list of judgments Kant thought he found in ordinary logic, and from it he drew up his well-known scheme of the twelve categories. These forms are the determinations of all objects of experience, for it is only through them that the manifold of sense can be reduced to the unity of consciousness, and thereby constituted experience. They are a priori conditions, subjective in one sense, but objective as being universal, necessary and constitutive of experience.

The table of logical judgments with corresponding categories is as follows:—

Judgments.		Categories.
Universal Particular Singular	I. Of Quantity	Unity. Plurality. Totality.
Affirmative Negative Infinite	II. Of Quality	Reality. Negation. Limitation.
Categorical Hypothetical Disjunctive	III. Of Relation	Inherence and Subsistence (Substance and Accident). Causality and Dependence (Cause and Effect). Community (Reciprocity).
Problematical Assertoric Apodictic	IV. Of Modality	Possibility and Impossibility. Existence and Non-Existence. Necessity and Contingency.

Kant, it is well known, criticizes Aristotle severely for having drawn up his categories without a principle, and claims to have disclosed the only possible method by which an exhaustive classification might be obtained. What he criticized in Aristotle is brought against his own procedure by the later German thinkers, particularly Fichte and Hegel. And in point of fact it cannot be denied that Kant has allowed too much completeness to the ordinary logical distribution of propositions; he has given no proof that in these forms are contained all species of synthesis, and in consequence he has failed to show that in the categories, or pure conceptions, are contained all the modes of a priori synthesis. Further, his principle has so far the unity he claimed for it, the unity of a single function, but the specific forms in which such unity manifests itself are not themselves accounted for by this principle. Kant himself hints more than once at the possibility of a completely rational system of the categories, at an evolution from one single movement of thought, and in his Remarks on the Table of the Categories gave a pregnant hint as to the method to be employed. From any complete realization of this suggestion Kant, however, was precluded by one portion of his theory. The categories, although the necessary conditions under which alone an object of experience can be thrown, are merely forms of the mind’s own activity; they apply only to sensuous and consequently subjective material. Outside of and beyond them lies the thing-in-itself, which to Kant represented the ultimately real. This subjectivism was a distinct hiatus in the Kantian system, and against it principally Fichte and Hegel directed criticism. It was manifest that at the root of the whole Fichte. system of categories there lay the synthetizing unity of self-consciousness, and it was upon this unity that Fichte fixed as giving the possibility of a more complete and rigorous deduction of the pure notions of the understanding. Without the act of the Ego, whereby it is self-conscious, there could be no knowledge, and this primitive act or function must be, he saw, the position or affirmation of itself by the Ego. The first principle then must be that the Ego posits itself as the Ego, that Ego = Ego, a principle which is unconditioned both in form and matter, and therefore capable of standing absolutely first, of being the prius in a system. Metaphysically regarded this act of self-position yields the categories of Reality. But, so far as matter is concerned, there cannot be affirmation without negation, omnis determinatio est negatio. The determination of the Ego presupposes or involves the Non-Ego. The form of the proposition in which this second act takes to itself expression, the Ego is not = Not-Ego, is unconditioned, not derivable from the first. It is the absolute antithesis to the primitive thesis. The category of Negation is the result of this second act. From these two propositions, involving absolutely opposed and mutually destructive elements, there results a third which reconciles both in a higher synthesis. The notion in this third is determination or limitation; the Ego and Non-Ego limit, and are opposed to one another. From these three positions Fichte proceeds to evolve the categories by a series of thesis, antithesis and synthesis.

In thus seizing upon the unity of self-consciousness as the origin for systematic development, Fichte has clearly taken a step in advance of, and yet in strict harmony with, the Kantian doctrine. For, after all that can be said as to the demonstrated character of formal logic, Kant’s procedure was empirical, and only after the list of categories had been drawn out, did he bring forward into prominence what gave them coherence and reality. The peculiar method of Fichte, also, was nothing but a consistent application of Kant’s own Remark on the Table of the Categories. Fichte’s doctrine, however, is open to some of the objections advanced against Kant. His method is too abstract and external, and wants the unity of a single principle. The first two of his fundamental propositions stand isolated from one another, not to be resolved into a primitive unity. With him, too, the whole stands yet on the plane of subjectivity. He speaks, indeed, of the universal Ego as distinct from the empirical self-consciousness; but the universal does not rise with him to concrete spirit. Nevertheless the Wissenschaftslehre contains the only real advance in the treatment of the categories from the time of Kant to that of Hegel.9 This, of course, does not imply that there were not certain elements in Schelling, particularly in the Transcendental Idealism, that are of value in the transition to the later system; but on the whole it is only in Hegel that the whole matter of the Kantian categories has been assimilated and carried to a higher stage. The Hegelian philosophy, in brief, is a system of the categories; and, as it is not intended here to expound that philosophy, it is impossible to give more than a few general and quite external observations as to the Hegelian mode of viewing these elements of thought. With Kant, as has been seen, the categories were still subjective, not as being forms of the individual subject, but as having over against them the world of noumena to which they were inapplicable. Self-consciousness, which was, even with Kant, the nodus or kernel whence the categories sprang, was nothing but a logical centre,—the reality was concealed. There was thus a dualism, to overcome which is the first step in the Hegelian system. The principle, if there is to be one, must be universally applicable, all-comprehensive. Self-consciousness is precisely the principle wanted; it is a unity, an identity, containing in itself a multiplicity. The universal in absolute self-consciousness is just pure thinking, which in systematic evolution is the categories; the particular is the natural or multiform, the external as such; the concrete of both is spirit, or self-consciousness come to itself. The same law that obtains among the categories is found adequate to an explanation of the external thing which had so sadly troubled Kant. The categories themselves are moments of the universal of thought, type forms, or definite aspects which thought assumes; determinations, Bestimmungen, as Hegel most frequently calls them. They evolve by the same law that was found to be the essence of ultimate reality—i.e. of self-consciousness. The complete system is pure thought, the Universal par excellence.

After the Hegelian there can hardly be said to have been a philosophical treatment of the categories in Germany which is not more or less a criticism of that system. It does not seem necessary to mention the unimportant modifications introduced by Kuno Fischer, J.E. Erdmann, or others belonging to the school. In the strongly-opposed philosophy of J.F. Herbart the categories can hardly be said to hold a prominent place. They are, with him, the most general notions which are psychologically formed, and he classifies them as follows:—(1) Thing, either as product of thought or as given in experience; (2) Property, either qualitative or quantitative; (3) Relation; (4) The Negated. Along with these he posits as categories of inner process—(1) Sensation, (2) Cognition, (3) Will, (4) Action. Joh. Fr. L. George (1811-1873),10 who in the main follows Schleiermacher, draws out a table of categories which shows, in some points, traces of Herbartian influence. His arrangement by enneads, or series of nine, is fanciful, and wanting in inner principle.

The most imposing of more recent attempts at a reconstruction of the categories is that of F.A. Trendelenburg. To him the first principle, or primitive reality, is Motion, which is both real as external movement, and ideal as inner construction. Trendelenburg. The necessary conditions of Motion are Time and Space, which are both subjective and objective. From this point onwards are developed the mathematical (point, line, &c.) and real (causality, substance, quantity, quality, &c.) categories which appear as involved in the notion of motion. Matter cannot be regarded as a product of motion; it is the condition of motion, we must think something moved. All these categories, “under the presupposition of motion as the first energy of thought, are ideal and subjective relations; as also, under the presupposition of motion as the first energy of Being, real and objective relations.”11 A serious difficulty presents itself in the next category, that of End (Zweck), which can easily be thought for inner activity, but can hardly be reconciled with real motion. Trendelenburg solves the difficulty only empirically, by pointing to the insufficiency of the merely mechanical to account for the organic. The consideration of Modality effects the transition to the forms of logical thought. On the whole, Trendelenburg’s unique fact of motion seems rather a blunder. There is much more involved than he is willing to allow, and motion per se is by no means adequate to self-consciousness. His theory has found little favour.

Hermann Ulrici works out a system of the categories from a psychological or logical point of view. To him the fundamental fact of philosophy is the distinguishing activity (unterscheidende Tätigkeit) of thought. Thought is only possible Ulrici. by distinction, difference. The fixed points in the relations of objects upon which this activity turns are the categories, which may be called the forms or laws of thought. They are the aspects of things, notions under which things must be brought, in order to become objects of thought. They are thus the most general predicates or heads of predicates. The categories cannot be completely gathered from experience, nor can they be evolved a priori; but, by attending to the general relations of thought and its purely indefinite matter, and examining what we must predicate in order to know Being, we may attain to a satisfactory list. Such a list is given in great detail in the System der Logik (1852), and in briefer, preciser form in the Compendium der Logik (2nd ed., 1872); it is in many points well deserving of attention.

The definition of the categories by the able French logician Charles Bernard Renouvier in some respects resembles that of Ulrici. To him the primitive fact is Relation, of which all the categories are but forms. “The categories,” he says, “are the Renouvier, Cousin, Hamilton, Mill. primary and irreducible laws of knowledge, the fundamental relations which determine its form and regulate its movements.” His table and his criticism of the Kantian theory are both of interest.12 The criticism of Kant’s categories by Cousin and his own attempted classification are of no importance. Of little more value is the elaborate table drawn out by Sir W. Hamilton.13 The generalized category of the Conditioned has but little meaning, and the subordinate categories evolve themselves by no principle, but are arranged after a formal and quite arbitrary manner. They are never brought into connexion with thought itself, nor could they be shown to spring from its nature and relations. J.S. Mill presented, “as a substitute for the abortive classification of Existences, termed the categories of Aristotle,” the following as an enumeration of all nameable things:—(1) Feelings, or states of consciousness; (2) The minds which experience these feelings; (3) Bodies, or external objects which excite certain of those feelings; (4) Successions and co-existences, likenesses and unlikenesses, between feelings or states of consciousness.14 This classification proceeds on a quite peculiar view of the categories, and is here presented only for the sake of completeness.

By modern psychologists the subject has been closely investigated. Professor G.F. Stout (Manual of Psychology, vol. ii. pp. 312 foll.) defines categories as “forms of cognitive consciousness, universal principles or relations presupposed either in all Modern psychologists. cognition or in all cognition of a certain kind.” He then treats External (or Physical) Reality, Space, Time, Causality and “Thinghood” from the standpoint of the perceptual consciousness; showing in what sense the categories of causality, substance and the rest exist in the sphere of perception. As contrasted with the ideational, the perceptual consciousness is concerned with practice. Perception tells the child of things as separate entities, not in their ultimate relations as parts of a coherent whole. G.T. Ladd (Psychology Descriptive and Explanatory, ch. xxi., on “Space, Time and Causality”) defines the categories from the psychological standpoint as “those highly abstract conceptions which the mind frames by reflection upon its own most general modes of behaviour. They are our own notions resulting from co-operation of imagination and judgment, concerning the ultimate and unanalyzable forms of our own existence and development.” In other words, the categories are highly abstract, have no content, and are realized as a kind of thinking which has for its object all the other mental processes.

Authorities.—Besides those quoted above, see Eduard v. Hartmann, Kategorienlehre (Leipzig, 1896), and “Begriff der Kategorialfunktion”, in Zeitschr. f. Philos. und phil. Krit. cxv. (1899), pp. 9-19; E. König in the same periodical cxiii. (1889), pp. 232-279, and cxiv. (1899), pp. 78-105; F.A. Trendelenburg, Geschichte der Kategorienlehre (1846); P. Ragnisco Storia critica delle categorie (2 vols., Florence, 1871); W. Windelband Vom System der Kategorien (Tübingen, 1900); R. Eisler, Wörterbuch der philospphischen Begriffe (Berlin, 1899), pp. 400-409; S. Joda, Studio critico su le categorie (Naples, 1881); H. Vaihinger, Die transcendentale Deduktion der Kategorien (Halle, 1902); H.W.B. Joseph, Introduction to Logic (Oxford, 1906), ch. iii.; F.H. Bradley, Principles of Logic (1883); B. Bosanquet’s Knowledge and Reality (1885, 2nd ed. 1892); histories of philosophy. For further authorities see works quoted under Aristotle and Kant, and in J.M. Baldwin’s Dict. Philos. Psych. vol. iii. pt. 2, p. 685.