A Commentary to Kant's 'Critique of Pure Reason'

by Norman Kemp Smith

The absence of contradiction is in itself a sufficient guarantee of possibility, i.e. even of the possibility of real existence. How very far Leibniz is willing to go on this line is shown by his acceptance of the ontological argument. The whole weight of his system rests, indeed, upon this proof. The notion of God is, he maintains, the sole concept which can determine itself in a purely logical manner not only as possible but also as real. If we are to avoid violating the principle of contradiction, the Ens perfectissimum must be regarded as possessing the perfection of real existence. And since God is perfect in moral as in all other attributes, His actions must be in conformity with moral demands. In creating the natural order God must therefore have chosen that combination of possibilities which constitutes the best of all possible worlds. By means of this conceptual bridge we are enabled to pass by pure a priori thinking from the logically possible to the factually real.

Pure logical thinking is thus an instrument whereby ultimate reality can be defined in a valid manner. Pure thought is speculative and metaphysical in its very essence. It uncovers to us what no experience can reveal, the wider universe which exists eternally in the mind of God. Every concept (whether mathematical, dynamical, or moral), provided only that it is not self-contradictory, is an eternal essence, with the intrinsic nature of which even God must reckon in the creation of things. When, therefore, we are determining the unchanging nature of the eternally possible, there is no necessary reference to Divine existence. The purely logical criterion suffices as a test of truth. Every judgment which is made in regard to such concepts must express only what their content involves. All such judgments must be analytic in order to be true.

When, however, we proceed from the possible to the real, that is to say, from the necessary to the contingent, the logical test is no longer sufficient; and only by appeal to the second principle, that of sufficient reason, can judgments about reality be logically justified. Whether or not the principle of sufficient reason is deducible, as Wolff sought to maintain, from the principle of contradiction, is a point of quite secondary importance. That is a question which does not deserve the emphasis which has been laid upon it. What is chiefly important is that for Leibniz, as for Wolff, both principles are principles of analysis. The principle of sufficient reason is not an instrument for determining necessary relations between independent substances. The sufficient ground of a valid predicate must in all cases be found in the concept of the subject to which it is referred. The difference between the two principles lies elsewhere, namely, in the character of the connection established between subject and predicate. In the one case the denial of the proposition involves a direct self-contradiction. In the other the opposite of the judgment is perfectly conceivable; our reason for asserting it is a moral (employing the term in the eighteenth-century sense), not a logical ground. The subject is so constituted, that in the choice of ends, in pursuit of the good, it must by its very nature so behave. The principle of sufficient reason, which represents in our finite knowledge the divine principle of the best, compels us to recognise the predicate as involved in the subject—as involved through a ground which inclines without necessitating. Often the analysis cannot be carried sufficiently far to enable us thus to transform a judgment empirically given into one which is adequately grounded. None the less, in recognising it as true, we postulate that the predicate is related to the subject in this way. There are not for Leibniz two methods of establishing truth, sense-perception to reveal contingent fact, and general reasoning to establish necessary truth. A proposition can be accepted as true only in so far as we can at least postulate, through absence of contradiction and through sufficient reason, its analytic character. It must express some form of identity. The proposition, Caesar crossed the Rubicon, is given us as historical fact. The more complete our knowledge of Caesar and of his time, the further we can carry the analysis; and that analysis if completely executed would displace the merely factual validity of the judgment by insight into its metaphysical truth. Thus experience, with its assertions of the here and now about particulars inexhaustibly concrete, sets to rational science an inexhaustible task. We can proceed in our analysis indefinitely, pushing out the frontiers of thought further and further into the empirical realm. Only by the Divine Mind can the task be completed, and all things seen as ordered in complete obedience to the two principles of thought.

Leibniz, in propounding this view, develops a genuinely original conception of the relation holding between appearance and reality. Only monads, that is, spiritual beings, exist. Apart from the representative activity of the monads there are no such existences as space and time, as matter and motion. The mathematical and physical sciences, in their present forms, therefore, cannot be interpreted as revealing absolute existences. But, if ideally developed, they would emancipate themselves from mechanical and sensuous notions; and would consist of a body of truths, which, as thus perfected, would be discovered to constitute the very being of thought. Pure thought or reason consists in the apprehension of such truths. To discover and to prove them thought does not require to issue out beyond itself. It creates this conceptual world in the very act of apprehending it; and as this realm of truth thus expresses the necessary character of all thought, whether divine or human, it is universal and unchanging. Each mind apprehends the same eternal truth; but owing to imperfection each finite being apprehends it with some degree of obscurity and confusion, fragmentarily, in terms of sense, and so falls prey to the illusion that the self stands in mechanical relations to a spatial and temporal world of matter and motion.

Leibniz supports this doctrine by his theory of sense-experience as originating spontaneously from within the individual mind. Thereby he is only repeating that pure thought generates its whole content from within itself. Sense-experience, in its intrinsic nature, is nothing but pure thought. Such thought, owing to the inexhaustible wealth of its conceptual significance, so confuses the mind which thus generates it, that only by prolonged analysis can larger and larger portions of it be construed into the conceptual judgments which have all along constituted its sole content. And in the process, space, time, and motion lose all sensuous character, appearing in their true nature as orders of relation which can be adequately apprehended only in conceptual terms. They remain absolutely real as objects of thought, though as sensible existences they are reduced to the level of mere appearance. Such is the view of thought which is unfolded in Leibniz’s writings, in startling contrast to the naturalistic teaching of his Scotch antagonist.

As already indicated, Kant’s first-hand knowledge of Leibniz’s teaching was very limited. He was acquainted with it chiefly through the inadequate channel of Wolff’s somewhat commonplace exposition of its principles. But even from such a source he could derive what was most essential, namely, Leibniz’s view of thought as absolute in its powers and unlimited in its claims. How closely Wolff holds to the main tenet of Leibniz’s system appears from his definition of philosophy as “the science of possible things, so far as they are possible.” He thus retains, though without the deeper suggestiveness of Leibniz’s speculative insight, the view that thought precedes reality and legislates for it. By the possible is not meant the existentially or psychologically possible, but the conceptually necessary, that which, prior to all existence, has objective validity, sharing in the universal and necessary character of thought itself.

As Riehl has very justly pointed out,[1789] Wolff’s philosophy had, prior even to the period of Kant’s earliest writings, been displaced by empirical, psychological enquiries and by eclectic, popular philosophy. Owing to the prevailing lack of thoroughness in philosophical thinking, “Problemlosigkeit” characterised the whole period. The two exclusively alternative views of the function of thought stood alongside one another within each of the competing systems, quite unreconciled and in their mutual conflict absolutely destructive of all real consistency and thoroughness of thought. It was Kant who restored rationalism to its rightful place. He reinvigorated the flaccid tone of his day by adopting in his writings, both early and late, the strict method of rational science, and by insisting that the really crucial issues be boldly faced. In essentials Kant holds to Wolff’s definition of philosophy as “the science of possible things, so far as they are possible.” As I have just remarked, the possible is taken in an objective sense, and the definition consequently gives expression to the view of philosophy upon which Kant so frequently insists, as lying wholly in the sphere of pure a priori thought. Its function is to determine prior to specific experience what experience must be; and obviously that is only possible by means of an a priori, purely conceptual method. His Critique, as its title indicates, is a criticism of pure reason by pure reason. Nothing which escapes definition through pure a priori thinking can come within its sphere. The problem of the “possibility of experience” is the problem of discovering the conditions which necessarily determine experience to be what it is. Kant, of course, radically transforms the whole problem, in method of treatment as well as in results, when in defining the subject-matter of enquiry he substitutes experience for things absolutely existent. This modification is primarily due to the influence of Hume. But the constant occurrence in Kant’s philosophy of the term “possibility” marks his continued belief in the Idealist view of thought. Though pure thought never by itself amounts to knowledge—therein Kant departs from the extreme rationalist position—only through it is any knowledge, empirical or a priori, possible at all. Philosophy, in order to exist, must be a system of a priori rational principles. Nothing empirical or hypothetical can find any place in it.[1790] Yet at the same time it is the system of the a priori conditions only of experience, not of ultimate reality. Such is the twofold relation of agreement and difference in which Kant stands to his rationalist predecessors.

INDEX

[A], [B], [C], [D], [E], [F], [G], [H], [I], [J], [K], [L], [M], [N], [O], [P], [Q], [R], [S], [T], [U], [V], [W], [Z]

Absolute. See Unconditioned
Absolutist aspect of human consciousness, [xxx-xxxiii], [liii], [liv-lv], [lvi-lvii], [270-1], [274], [282], [285-7], [331] n., [423] n.
Actuality, [391] ff.
Adamson, R., [38], [311], [314]
Addison, [156]
Adickes, E., [xx-xxi], [76], [166], [200], [215] n., [233] n., [234], [304], [363], [376], [397], [406] n., [423], [439-40], [441], [464] n., [466], [479], [579] n., [601] n.
Affinity, objective, [224], [253-7], [266-7]
“Als ob” doctrine, [524], [553] ff.
Analogy, Kant’s use of the term, [356-8]
Analytic and synthetic judgment, [xxv] ff., [xxxv-xxxvi], [xxxviii], [28] ff., [37] ff., [59-60], [65];
existential judgment, [530-1];
distinction perhaps suggested by examination of ontological argument, [531].
See Judgment
Analytic and synthetic methods, [44] ff., [111], [117] n.
See Transcendental method
Analytic, distinguished from the Dialectic, [172-4], [438-42]
Anthropologie, Kant’s, [81] n., [100] n.
Antinomies, [lii], [liii], [432], [478] ff., [519-20]
Appearance, Kant’s views regarding, [xxxvii], [xlvi-xlvii], [liii-liv], [18-22], [83-5], [120-2], [147] ff., [205] ff., [215] ff., [279-284], [293] ff., [301] ff., [312] ff., [321] ff., [330-1], [372-3], [404] ff., [427] ff.;
criticism of Leibnizian view of, [143-6];
criticism of Locke’s view of, [146-7];
ideality of, [147] ff.;
outer and inner appearances reduce to relations, [147-8];
appearance and illusion, [148] ff.;
causal efficacy of appearances, [216], [217-18], [351], [373-4];
distinction between appearance and reality based not on categories of understanding but on Ideas of Reason, [liii-liv], [217-18], [326] n., [331], [390-1], [414-17], [426-31], [473-7], [511-12], [519-21], [541-2], [558-61]
Apperception, and memory, [251];
in what sense origina[l], [xxxiv], [xliii-xlv], [l-lii], [260-3], [461-2], [472-7];
transcendental unity of, [l-lii], [207] ff., [212], [250-3], [260-3], [270], [277-9], [322] ff., [455] ff., [473-7];
absent from the animal mind, [xlvii-l];
objective unity of, [270-1], [274], [282], [285-7];
and inner sense, [295-8], [321] ff., [512] n.
See Self
A priori, Kant’s views regarding the, [xxvi-xxviii], [xxxiii-xxxvi], [lii-lv], [1-2], [39-40], [42], [54] ff.;
problem of a priori synthetic judgment, [26] ff., [39-40], [43] ff.;
its validity merely de facto, [xxxv-xxxvi], [xliv], [30], [57], [118], [142], [185-6], [257-9], [291], [391-2], [393], [400-1], [411];
the faculties in which it originates, [xliii-xlv], [l-lii], [1-2], [50-1], [237-8], [263] ff., [391-2], [393], [398], [563-5];
semi-Critical view of the, [188-9], [232], [263-4].
See Understanding, Reason
Aquinas, [73]
Architectonic, [xxii], [100], [184], [332-6], [340-1], [342], [343], [345], [347], [390], [392], [394], [419] ff., [434], [437], [440], [439-40], [454], [463], [464], [474], [479-80], [496], [498], [542], [563], [579]
Aristotle, [xlv], [196], [198], [390]. See Logic
Arithmetic, [32], [40-1], [65-6], [128] ff., [337-8], [347], [566]
Association, and judgment, [xxxiv-xxxv], [xlviii-l];
and consciousness, [xli-xlii]; rests on objective affinity, [253-7], [266-7]
Attributive judgment, Kant’s exclusive emphasis upon, [37-8], [180-1], [197]
Augustine, St., [73], [110], [565]
Avenarius, [587] n.
Axioms, Kant’s view of, [50], [127], [348], [565-7]
Bacon, Francis, [4-5], [74]
Bain, A., [86] n.
Balfour, A. J., [314]
Baumgarten, [192-3], [441], [522]
Beantwortung der Frage: Was heisst Aufklärung? Kant’s, [15]
Beattie, James, [xxviii-xxix], xxxi n., [207], [582], [595], [600] n.
Beck, [80]
Belief, Kant’s view of, [lv] ff., [576-7]
Beloselsky, Fürst von, [xlix]
Bergson, [86], [142], [359-60] n., [587] n.
Berkeley, [xxxii], [xl], [xlvi], [112], [153-4], [155] ff., [272], [298] ff., [587-8], [592], [595], [596]
Borowski, [63], [156]
Bosanquet, B., [36], [181], [197]
Bradley, F. G., [36], [181], [197]
Bruno, Giordano, [74]
Bülffinger, [155]
Caird, E., [xx], [1] n., [23], [51], [102] n., [114], [117], [183], [194], [195], [262], [296], [314], [328], [340], [357] n., [359] n., [373], [378], [399], [462], [468]
Campanella, [74]
Canon, [72], [169-70], [174], [332-3], [438], [569] ff.
Cassirer, E., [132]
Categorical imperative, [xxxvi], [lvi-lviii], [571] ff.
Categories, distinction from generic concept, [178] ff.;
de facto nature of the, [xxxv-xxxvi], [xxxviii], [xliv], [30], [57], [185-6], [257-8], [291], [391-2], [398], [400-1], [411];
definition of the, [195-6], [198], [339-42], [404-5];
semi-Critical view of the, [188-9], [217-18], [232], [263-4];
merely logical forms, [xxxv-xxxvi], [xxxviii], [30] n., [32], [39], [108], [176] ff., [185-6], [191], [195-196], [257-8], [290-1], [325] ff., [339-40], [398], [404-5], [409-10], [413-14], [467];
valid only for appearances, [259-60];
and schemata, [195-6], [311], [333], [339-342], [467] n.;
metaphysical deduction of the, [183] ff., [192] ff., [287-8];
transcendental deduction of the, [234] ff., [287-8];
all categories involved in every act of consciousness, [xli-xlv], [liii-liv], [199-200], [356], [368], [370], [377], [387-91];
have wider scope than the forms of sense, [lv-lvi], [20], [25], [290-1], [331], [404] ff.;
restricted by time and space, [342], [357];
in relation to outer and inner experience, [311-12];
how far predicable of the ‘I think,’ [325] ff.;
how far applicable to sensations, desires, etc., xlvi n., [275-6], [279] ff., [312] ff., [384-5], [476];
proof of specific, [242-3], [252-3], [258-9], [287-8], [333], [343-4];
determinate and indeterminate application of the, [325] ff., [405] ff.;
may be intrinsically inapplicable to things in themselves, [290], [409-10], [413-14];
category of existence, [322], [415] n.;
category of totality and Idea of the unconditioned, [199-200], [433], [451], [480], [529];
mathematical and dynamica[l], [198], [345-7], [510-11].
See A priori, Understanding
Catharticon, [169], [174]
Causality, Kant influenced by Hume’s teaching regarding, [xxv] ff., [61-4], [364] ff., [593-600];
Kant’s treatment of the principle of, [363] ff.;
Kant’s subjectivist and phenomenalist views of, [216], [217-18], [318-21], [351], [373-4];
sensations, feelings, etc. subject to principle of, xlvi n., [275], [279-82], [312], [384-5];
category of, involved in consciousness of time, [liii-liv], [365] ff., [377] ff., [387];
and freedom, [492] ff.
See Hume
Clarke, [140], [539], [594]
Cohen, H., [51], [102] n., [195], [262], [340]
Coherence theory of truth, [xxxvi-xxxix], [36] ff., [173] n.;
criterion of truth bound up with the Ideas of Reason, [217-18], [326] n., [331], [390-1], [414-17], [426-31], [473-7], [511-12], [519-21], [541-2], [558-61]
Concept, Kant’s generic or class view of the, [99-100], [105-7], [118-19], [126], [132-3], [177-84], [338-9], [370-1], [377-84], [390-1];
intuition and conception, [38-42], [93-4], [105-9], [118-20], [126], [128-134], [165-6], [167-8], [194], [370], [390-1], [564-6];
construction of concepts, [41], [131-3], [338-9], [418] ff., [564-6];
concepts and images, [337-9];
Kant’s doctrine of the pure concept, [xxxix], [394-400], [418] ff.
See Understanding
Concerning the Advances, made, etc.
See Fortschritte
Consciousness, Kant’s views regarding, [xxxiv-xxxv], [xxxix-xlv], [xliii-xlvii], [l-lii];
and the animal mind, [xlvii-l];
may be a resultant, [xxxiv], [xliii-xlv], [l-lii], [261-3], [277-9], [327], [459-62], [473-7];
no immediate consciousness of mind’s own activities, [xliii-xlv], [l-lii], [263] ff., [273] ff., [293], [295] ff., [322] ff.;
consciousness of time Kant’s datum, [xxxiv], [120], [241] ff., [365] ff., [381] ff.;
absolutist aspect of, [xxx-xxxiii], [liii], [lvi-lvii], [270-1], [274], [282], [285-7], [331] n.
See Apperception, Judgment
Contingency, assertion of, [39] ff., [55], [286-9]
Continuity, Kant’s views regarding, [352-355], [488] ff., [509];
principle of, [380-1];
transcendental principle of, [551]
Copernicus, [18-19], [22-5]
Cosmological Argument, [531] ff.
Criterion of truth. See Coherence theory of truth
Criticism, Kant’s use of term, [1], [9], [13-14], [21];
Age of, [15]
Critique of Practical Reason, [lvi], [lvii], [lx], [77-8], [569] ff., [572]
Critique of Judgment, [lxi], [77], [83], [97-8], [191], [265], [537], [539], [561], [569] n., [574], [575] n., [576], [577] n.
Crusius, [xxviii], [xxxii], [47]
Curtius, E., [336]
Deduction of categories, distinction between subjective and objective, xliv n., [235] ff.;
subjective, [245] ff., [263] ff.; objective, [248] ff.;
metaphysica[l], [175] ff., [192] ff.;
stages in Kant’s development of metaphysica[l], [186] ff.
See Transcendental method of proof
Deduction of Ideas, metaphysica[l], [426], [433] ff., [450-4], [478-80], [522-3];
transcendenta[l], [426], [430], [436], [454], [552-4], [572] ff.
See Ideas of Reason
Definition, Kant’s view of, [564-5]
Deist, as contrasted with Theist, [541];
Kant’s deistic interpretation of the Ideas of Reason, [418], [436], [439-40], [454], [473-7], [520-1], [537], [542], [575].
See Idealist view of Reason.
Democritus, [354] n.
Demonstration, Kant’s view of, [566-7]
Descartes, [xxxi], [xxxix-xliii], [xlvi], [155], [157], [272-3], [279] ff., [298] ff., [354] n., [421], [449], [583-7], [589-90], [597]
Desires, Kant’s view of the, xlvi n., [276], [279-82], [312], [384-5]
Dewey, J., [36]
Dialectic, distinguished from the Analytic, [172-4], [438-42];
the problems of the, [425] ff.;
development of Kant’s views regarding the, [431] ff.
Dilucidatio Principiorum primorum, etc., Kant’s, [155], [299]
Discipline, [170], [174], [438],