The Online Library of Liberty

A project of Liberty Fund, Inc.

• Dedication
• Preface 1
• Translator’s Preface
• Translator’s Preface to Second Edition
• Introduction [p. 1]
• I: The Idea of Transcendental Philosophy
• II: Division of Transcendental Philosophy
• I: The Elements of Transcendentalism
• Part I: Transcendental Æsthetic [p. 19]
• Section I: Of Space
• Section II: Of Time
• Part II: Transcendental Logic [p. 50]
• Introduction the Idea of a Transcendental Logic
• I: Of Logic In General
• II: Of Transcendental Logic
• III: Of the Division of General Logic Into Analytic and Dialectic
• IV: Of the Division of Transcendental Logic Into Transcendental Analytic and Dialectic
• Division I: Transcendental Analytic In Two Books, With Their Chapters and Sections
• Book I: Analytic of Concepts
• Chapter I: Method of Discovering All Pure Concepts of the Understanding
• Section I: Of the Logical Use of the Understanding In General
• Section II: Of the Logical Function of the Understanding In Judgments [p. 70]
• Section III: Of the Pure Concepts of the Understanding, Or of the Categories
• Chapter II: Of the Deduction of the Pure Concepts of the Understanding [p. 84]
• Section I: Of the Principles of a Transcendental Deduction In General
• Section II: Of the a Priori Grounds For the Possibility of Experience
• I: Of the Synthesis of Apprehension In Intuition
• II: Of the Synthesis of Reproduction In Imagination
• III: Of the Synthesis of Recognition In Concepts [p. 103]
• IV: Preliminary Explanation of the Possibility of the Categories As Knowledge a Priori
• Section III: Of the Relation of the Understanding to Objects In General, and the Possibility of Knowing Them a Priori [p. 115]
• Book II: Analytic of Principles
• Introduction of the Transcendental Faculty of Judgment In General
• Chapter I: Of the Schematism of the Pure Concepts of the Understanding [p. 137]
• Chapter II: System of All Principles of the Pure Understanding [p. 148]
• Section I: Of the Highest Principle of All Analytical Judgments
• Section II: Of the Highest Principle of All Synthetical Judgments [p. 154]
• Section III: Systematical Representation of All Synthetical Principles of the Understanding
• I: [of the Axioms of Intuition 1 Principle of the Pure Understanding
• II: [ Anticipations of Perception
• III: [ the Analogies of Experience
• IV: The Postulates of Empirical Thought In General
• Chapter III: On the Ground of Distinction of All Subjects Into Phenomena and Noumena
• I.: Identity and Difference
• II.: Agreement and Opposition
• III.: The Internal and the External
• IV.: Matter and Form
• Note On the Amphiboly of Reflective Concepts
• Division II: Transcendental Dialectic In Two Books, With Their Chapters and Sections [p. 293]
• Introduction: 1.
• Book I: Of the Concepts of Pure Reason [p. 310]
• First Section of Ideas In General
• Second Section of Transcendental Ideas [p. 321]
• Third Section System of Transcendental Ideas [p. 333]
• Book II: Of the Dialectical Conclusions of Pure Reason
• Chapter I: Of the Paralogisms of Pure Reason [p. 341]
• Chapter II: The Antinomy of Pure Reason
• Section I: System of Cosmological Ideas
• Section II: Antithetic of Pure Reason
• Section III: Of the Interest of Reason In These Conflicts [p. 462]
• Section IV: Of the Transcendental Problems of Pure Reason, and the Absolute Necessity of Their Solution
• Section V: Sceptical Representation of the Cosmological Questions In the Four Transcendental Ideas [p. 485]
• Section VI: Transcendental Idealism As the Key to the Solution of Cosmological Dialectic
• Section VII: Critical Decision of the Cosmological Conflict of Reason With Itself
• Section VIII: The Regulative Principle of Pure Reason With Regard to the Cosmological Ideas [p. 508]
• Section IX: Of the Empirical Use of the Regulative Principle of Reason With Regard to All Cosmological Ideas
• Chapter III: The Ideal of Pure Reason
• Section I: Of the Ideal In General
• Section II: Of the Transcendental Ideal ( Prototypon Transcendentale )
• Section III: Of the Arguments of Speculative Reason In Proof of the Existence of a Supreme Being
• Section IV: Of the Impossibility of an Ontological Proof of the Existence of God [p. 592]
• Section V: Of the Impossibility of a Cosmological Proof of the Existence of God [p. 603]
• Section VI: Of the Impossibility of the Physico-theological Proof
• Section VII: Criticism of All Theology Based On Speculative Principles of Reason [p. 631]
• Chapter I: The Discipline of Pure Reason
• Section I: The Discipline of Pure Reason In Its Dogmatical Use
• Section II: The Discipline of Pure Reason In Its Polemical Use
• Section III: The Discipline of Pure Reason With Regard to Hypotheses
• Section IV: The Discipline of Pure Reason With Regard to Its Proofs
• Chapter II: The Canon of Pure Reason [p. 795]
• First Section: of the Ultimate Aim of the Pure Use of Our Reason
• Section II: Of the Ideal of the Summum Bonum As Determining the Ultimate Aim of Pure Reason
• Section III: Of Trowing, Knowing, and Believing [p. 820]
• Chapter III: The Architectonic of Pure Reason [p. 832]
• Chapter IV: The History of Pure Reason [p. 852]
• Supplement I: Motto to Second Edition
• Supplement II: Preface to the Second Edition. 1787. [p. Vii]
• Supplement III: Supplement Iv
• Supplement V
• Supplement Vi
• Supplement V
• Supplement Vi
• Supplement Vii
• Supplement Viii
• Supplement Ix
• Supplement X
• Supplement Xi
• Supplement Xii
• Supplement Xiii
• Supplement Xiv
• Supplement Xv
• Supplement Xvi a
• Supplement Xvi B
• Supplement Xvii
• Supplement Xviii
• Supplement Xix
• Supplement Xx
• Supplement Xxi
• Supplement Xxii
• Supplement Xxiii
• Supplement Xxiv
• Supplement Xxv
• Supplement Xxvi
• Supplement Xxvii
• Supplement Xxviii

Section II

The Discipline of Pure Reason in its Polemical Use

Reason in all her undertakings must submit to criticism, and cannot attempt to limit the free exercise of such criticism without injury to herself, and without exposing herself to dangerous suspicion. There is nothing so important with reference to its usefulness, nothing so sacred, that it could withdraw itself from that searching examination which has no respect of persons. The very existence of reason depends on that freedom; for reason can claim no dictatorial authority, but its decrees are rather like the votes of free citizens, every one of whom may freely express, not only his doubts, but even [p. 739] his veto.

But, though reason can never refuse to submit to criticism, it does not follow that she need always be afraid of it, while pure reason in her dogmatical (not mathematical) use is not so thoroughly conscious of having herself obeyed her own supreme laws as not to appear with a certain shyness, nay, without any of her assumed dogmatical authority, before the tribunal of a higher judicial reason.

The case is totally different when reason has to deal, not with the verdicts of a judge, but with the claims of her fellow-citizens, and has to defend itself only against these claims. For as these mean to be as dogmatical in their negations as reason is in her affirmations, reason may justify herself κατ’ ἄνθρωπον, so as to be safe against all damages, and with a good title to her own property that need not fear any foreign claims, although κατ’ ἀλήθειαν it could not itself be established with sufficient evidence.

By the polemical use of pure reason I mean the defence of her own propositions against dogmatical negations. Here the question is not, whether her own assertions may not themselves be false, but it is only to be shown that no one is ever able to prove the opposite with apodictic certainty, nay, even with a higher degree of plausibility. For we are not on sufferance in our possession, [p. 740] when, though our own title may not be sufficient, it is nevertheless quite certain that no one can ever prove its insufficiency.

It is sad, no doubt, and discouraging, that there should be an antithetic of pure reason, and that reason, being the highest tribunal for all conflicts, should be in conflict with herself. We had on a former occasion to treat of such an apparent antithetic, but we saw that it arose from a misunderstanding, phenomena, according to the common prejudice, being taken for things in themselves, and an absolute completeness of their synthesis being demanded in one way or other (being equally impossible in either way), a demand entirely unreasonable with regard to phenomena. There was, therefore, no real contradiction in reason herself when making the two propositions, first, that the series of phenomena given by themselves has an absolutely first beginning; and, secondly, that the series is absolutely and by itself without any beginning; for both propositions are perfectly consistent with each other, because phenomena, with regard to their existence as phenomena, are by themselves nothing, that is, something self-contradictory, so that their hypothesis must naturally lead to contradictory inferences. [p. 741]

We cannot, however, appeal to a similar misunderstanding, in order to remove the conflict of reason, when it is said, for instance, on one side, theistically, that there is a Supreme Being, and on the other, atheistically, that there is no Supreme Being; or if in psychology it is maintained that everything which thinks possesses an absolute and permanent unity and is different, therefore, from all perishable material unity, while others maintain that a soul is not an immaterial unity, and not exempt, therefore from perishableness. For here the object of the question is free from anything heterogeneous or contradictory to its own nature, and our understanding has to deal with things by themselves only and not with phenomena. Here, therefore, we should have a real conflict, if only on the negative side pure reason could advance anything like the ground of an assertion. We may well admit the criticism of the arguments advanced by those who dogmatically assert, without therefore having to surrender these assertions, which are supported at least by the interest of reason, to which the opposite party cannot appeal.

I cannot share the opinion so frequently expressed by excellent and thoughtful men (for instance Sulzer) who, being fully conscious of the weakness of the proofs hitherto advanced, indulge in a hope that the future would supply us with evident demonstrations of the two cardinal propositions of pure reason, namely, that there is a God, and that there is a future life. I am certain, on the [p. 742] contrary, that this will never be the case, for whence should reason take the grounds for such synthetical assertions, which do not refer to objects of experience and their internal possibility? But there is the same apodictic certainty that no man will ever arise to assert the contrary with the smallest plausibility, much less dogmatically. For, as he could prove it by means of pure reason only, he would have to prove that a Supreme Being, and that a thinking subject within us, as pure intelligence, is impossible. But whence will he take the knowledge that would justify him in thus judging synthetically on things far beyond all possible experience? We may, therefore, rest so completely assured that no one will ever really prove the opposite, that there is no need to invent any scholastic arguments. We may safely accept those propositions which agree so well with the speculative interests of our reason in its empirical use, and are besides the only means of reconciling them with our practical interests. As aganst our opponent, who must not be considered here as a critic only, we are always ready with our Non liquet. This must inevitably confound our adversary, while we need not mind his retort, because we can always fall back on the subjective maxim of reason, [p. 743] which our adversary cannot, and can thus, protected by it, look upon all his vain attacks with calmness and indifference.

Thus we see that there is really no antithetic of pure reason, for the only arena for it would be the field of pure theology and psychology, and on that field it is not able to support a champion in full armour and with weapons which we need be afraid of. He can only use ridicule and boasting, and these we may laugh at as mere child’s play. This ought to be a real comfort and inspire reason with new courage; for what else could she depend on, if she herself, who is called upon to remove all errors, were divided against herself, without any hope of peace and quiet possession?

Whatever has been ordained by nature is good for some purpose or other. Even poisons serve to counteract other poisons which are in our own blood, and they must not be absent therefore in a complete collection of medicines. The objections against the vain persuasions and the conceit of our own purely speculative reason are inspired by the very nature of that reason, and must therefore have their own good purpose, which must not be lightly cast aside. Why has Providence placed certain things, which concern our highest interests, so far beyond [p. 744] our reach that we are only able to apprehend them very indistinctly and dubiously, and our enquiring gaze is more excited than satisfied by them? It is very doubtful whether it is useful to venture on any bold answers with regard to such obscure questions, nay, whether it may not be detrimental. But one thing is quite certain, namely, that it is useful to grant to reason the fullest freedom, both of enquiry and of criticism, so that she may consult her own interest without let or hindrance. And this is done quite as much by limiting her insight as by enlarging it, while nothing but mischief must arise from any foreign interference or any attempt to direct reason, against her own natural inclination, towards objects forced upon her from without.

Allow, therefore, your adversary to speak reason, and combat him with weapons of reason only. As to any practical interests you need not be afraid, for in purely speculative discussions they are not involved at all. What comes to light in these discussions is only a certain antinomy of reason which, as it springs from the very nature of reason, must needs be listened to and examined. Rea son is thus improved only by a consideration of both sides of her subject. Her judgment is corrected by the very limitations imposed upon her. What people may differ about is not the matter so much as the tone and manner of these discussions. For, though you have to surrender the language of knowledge, it is perfectly open [p. 745] to you to retain the language of the firmest faith, which need not fear the severest test of reason.

If we could ask that dispassionate philosopher, David Hume, who seemed made to maintain the most perfect equilibrium of judgment, what induced him to undermine by carefully elaborated arguments the persuasion, so useful and so full of comfort for mankind, as that reason is sufficient to assert and to form a definite concept of a Supreme Being, he would answer, Nothing but a wish to advance reason in self-knowledge, and at the same time a certain feeling of indignation at the violence which people wish to inflict on reason by boasting of her powers, and yet at the same time preventing her from openly confessing her weakness of which she has become conscious by her own self-examination. If, on the contrary, you were to ask Priestley, who was guided by the principles of the empirical use of reason only and opposed to all transcendental speculation, what could have induced him to pull down two such pillars of religion as the freedom and immortality of our soul (for the hope of a future life is with him an expectation only of the miracle of a resuscitation), he, who was himself so pious and zealous a teacher of religion, could answer nothing but that he was concerned for reason, which must suffer if certain subjects are withdrawn from the laws of material nature, the only laws which we can accurately know and fix. It [p. 746] would be most unjust to decry the latter, who was able to combine his paradoxical assertions with the interests of religion, and to inflict pain on a well-intentioned man, simply because he could not find his way, the moment he strayed away from the field of natural science. And the same favour must be extended to the equally well-intentioned, and in his moral character quite blameless, Hume, who could not and would not leave his abstract speculations, because he was rightly convinced that their object lies entirely outside the limits of natural science, and within the sphere of pure ideas.

What then is to be done, especially with regard to the danger which is believed to threaten the commonwealth from such speculations? Nothing is more natural, nothing more fair than the decision which you have to come to. Let these people go! If they show talent, if they produce new and profound investigations, in one word, if they show reason, reason can only gain. If you have recourse to anything else but untrammelled reason, if you raise the cry of high treason, and call together the ignorant mob as it were to extinguish a conflagration — you simply render yourself ridiculous. For here the question is not what may be useful or dangerous to the commonwealth, but merely how far reason may advance in her speculations, which are independent of all practical interests; [p. 747] in fact, whether these speculations are to count for anything, or are to be surrendered entirely for practical considerations. Instead of rushing in, sword in hand, it is far wiser to watch the struggle from the safe seat of the critic. That struggle is very hard for the combatants themselves, while to you it need not be anything but entertaining, and, as the issue is sure to be without bloodshed, it may become highly improving to your own intellect. For it is extremely absurd to expect to be enlightened by reason, and yet to prescribe to her beforehand on which side she must incline. Besides, reason is naturally so subdued and checked by reason, that you need not send out patrols in order to bring the civil law to bear on that party whose victory you fear. In this dialectical war no victory is gained that need disturb your peace of mind.

Reason really stands in need of such dialectical strife, and it is much to be wished that it had taken place sooner, and with the unlimited sanction of the public, for, in that case, criticism would sooner have reached complete maturity, and disputes would have come to an end by each party becoming aware of the illusions and prejudices which caused their differences.

There is in human nature a certain disingenuousness which, however, like everything that springs [p. 748] from nature, must contain a useful germ, namely, a tendency to conceal one’s own true sentiments, and to give expression to adopted opinions which are supposed to be good and creditable. There is no doubt that this tendency to conceal oneself and to assume a favourable appearance has helped towards the progress of civilisation, nay, to a certain extent, of morality, because others, who could not see through the varnish of respectability, honesty, and correctness, were led to improve themselves by seeing everywhere these examples of goodness which they believed to be genuine. This tendency, however, to show oneself better than one really is, and to utter sentiments which one does not really share, can only serve provisionally to rescue men from a rude state, and to teach them to assume at least the appearance of what they know to be good. Afterwards, when genuine principles have once been developed and become part of our nature, that disingenuousness must be gradually conquered, because it will otherwise deprave the heart and not allow the good seeds of honest conviction to grow up among the tares of fair appearances.

I am sorry to observe the same disingenuousness, concealment, and hypocrisy even in the utterances of speculative thought, though there are here fewer hindrances in uttering our convictions openly and freely as we ought, and no advantage whatever in our not doing [p. 749] so. For what can be more mischievous to the advancement of knowledge than to communicate even our thoughts in a falsified form, to conceal doubts which we feel in our own assertions, and to impart an appearance of conclusiveness to arguments which we know ourselves to be inconclusive? So long as those tricks arise from personal vanity only (which is commonly the case with speculative arguments, as touching no particular interests, nor easily capable of apodictic certainty) they are mostly counteracted by the vanity of others, with the full approval of the public at large, and thus the result is generally the same as what would or might have been obtained sooner by means of pure ingenuousness and honesty. But where the public has once persuaded itself that certain subtle speculators aim at nothing less than to shake the very foundations of the common welfare of the people, it is supposed to be not only prudent, but even advisable and honourable, to come to the succour of what is called the good cause, by sophistries, rather than to allow to our supposed antagonists the satisfaction of having lowered our tone to that of a purely practical conviction, and having forced us to confess the absence of all speculative and apodictic certainty. I cannot believe this, nor can I admit that the intention of serving a good cause can ever be combined with trickery, misrepresentation, and fraud. That in weighing the arguments of a speculative discussion we ought to be honest, seems the least that [p. 750] can be demanded; and if we could at least depend on this with perfect certainty, the conflict of speculative reason with regard to the important questions of God, the immortality of the soul, and freedom, would long ago have been decided, or would soon be brought to a conclusion. Thus it often happens that the purity of motives and sentiments stands in an inverse ratio to the goodness of the cause, and that its supposed assailants are more honest and more straightforward than its defenders.

Supposing that I am addressing readers who never wish to see a just cause defended by unjust means, I may say that, according to our principles of criticism, and looking not at what commonly happens, but at what in all common fairness ought to happen, there ought to be no polemical use of reason at all. For how can two persons dispute on a subject the reality of which neither of them can present either in real, or even in possible experience, while they brood on the mere idea of it with the sole intention of eliciting something more than the idea, namely, the reality of the object itself? How can they ever arrive at the end of their dispute, as neither of them can make his view comprehensible and certain, or do more than attack and refute the view of his opponent? For this is the fate of all assertions of pure reason. They go beyond the conditions of all possible experience, where no proof [p. 751] of truth is to be found anywhere, but they have to follow, nevertheless, the laws of the understanding, which are intended for empirical use only, but without which no step can be made in synthetical thought. Thus it happens that each side lays open its own weaknesses, and each can avail itself of the weaknesses of the other.

The critique of pure reason may really be looked upon as the true tribunal for all disputes of reason; for it is not concerned in these disputes which refer to objects immediately, but is intended to fix and to determine the rights of reason in general, according to the principles of its original institution.

Without such a critique, reason may be said to be in a state of nature, and unable to establish and defend its assertions and claims except by war. The critique of pure reason, on the contrary, which bases all its decisions on the indisputable principles of its own original institution, secures to us the peace of a legal status, in which disputes are not to be carried on except in the proper form of a lawsuit. In the former state such disputes generally end in both parties claiming victory, which is followed by an uncertain peace, maintained chiefly by the civil power, while in the latter state a sentence is pronounced which, [p. 752] as it goes to the very root of the dispute, must secure an eternal peace. These never-ceasing disputes of a purely dogmatical reason compel people at last to seek for rest and peace in some criticism of reason itself, and in some sort of legislation founded upon such criticism. Thus Hobbes maintains that the state of nature is a state of injustice and violence, and that we must needs leave it and submit ourselves to the constraint of law, which alone limits our freedom in such a way that it may consist with the freedom of others and with the common good.

It is part of that freedom that we should be allowed openly to state our thoughts and our doubts which we cannot solve ourselves, without running the risk of being decried on that account as turbulent and dangerous citizens. This follows from the inherent rights of reason, which recognises no other judge but universal human reason itself. Here everybody has a vote; and, as all improvements of which our state is capable must spring from thence, such rights are sacred and must never be minished. Nay, it would really be foolish to proclaim certain bold assertions, or reckless attacks upon assertions which enjoy the approval of the largest and best portion of the commonwealth, as dangerous; for that would be to impart to them an importance which they do not possess. [p. 753] Whenever I hear that some uncommon genius has demonstrated away the freedom of the human will, the hope of a future life, or the existence of God, I am always desirous to read his book, for I expect that his talent will help me to improve my own insight into these problems. Of one thing I feel quite certain, even without having seen his book, that he has not disproved any single one of these doctrines; not because I imagine that I am myself in possession of irrefragable proofs of them, but because the transcendental critique, by revealing to me the whole apparatus of our pure reason, has completely convinced me that, as reason is insufficient to establish affirmative propositions in this sphere of thought, it is equally, nay, even more powerless to establish the negative on any of these points. For where is this so-called free-thinker to take the knowledge that, for instance, there exists no Supreme Being? This proposition lies outside the field of possible experience and, therefore, outside the limits of all human cognition. The dogmatical defender of the good cause I should not read at all, because I know beforehand that he will attack the sophistries of the other party simply in order to recommend his own. Besides, a mere defence of the common opinion does not supply so much material for new remarks as a strange and ingeniously contrived theory. The opponent of religion, himself dogmatical in his own way, would give me a [p. 754] valuable opportunity for amending here and there the principles of my own critique of pure reason, while I should not be at all afraid of any danger arising from his theories.

But it may be argued that the youth at least, entrusted to our academical teaching, should be warned against such writings, and kept away from a too early knowledge of such dangerous propositions, before their faculty of judgment, or we should rather say, before the doctrines which we wish to inculcate on them, have taken root, and are able to withstand all persuasion and pressure, from whatever quarter it may proceed.

Yes, if the cause of pure reason is always to be pleaded dogmatically, and if opponents are to be disposed of polemically, i.e. simply by taking up arms against them and attacking them by means of proofs of opposite opinions, nothing might seem for the moment more advisable, but nothing would prove in the long run more vain and inefficient than to keep the reason of youth in temporary tutelage, and to guard it against temptation for a time at least. If, however, curiosity or the fashion of the age should afterwards make them acquainted with such writings, will their youthful persuasion then hold good? He who is furnished with dogmatical weapons only in order to resist the attacks of his opponent, and is not able to analyse that hidden dialectic which is concealed in his own breast quite as much as in that of his opponent, sees sophistries which at all events have the charm of [p. 755] novelty, opposed to other sophistries which possess that charm no longer, and excite the suspicion of having imposed on the natural credulity of youth. He sees no better way of showing that he is no longer a child than by ignoring all well-meant warnings, and, accustomed as he is to dogmatism, he swallows the poison which destroys his principles by a new dogmatism.

The very opposite of this is the right course for academical instruction, provided always that it is founded on a thorough training in the principles of the criticism of pure reason. For, in order to practically apply these principles as soon as possible, and to show their sufficiency even when faced by the strongest dialectical illusion, it is absolutely necessary to allow the attacks, which seem so formidable to the dogmatist, to be directed against the young mind whose reason, though weak as yet, has been enlightened by criticism, so as to let him test by its principles the groundless assertions of his opponents one after the other. He cannot find it very difficult to dissolve them all into mere vapour, and thus alone does he early begin to feel his own power and is able to secure himself against all dangerous illusions which in the end lose all their fascination on him. It is true, the same blows which destroy the stronghold [p. 756] of his opponent must prove fatal also to his own speculative structures, if he should wish to erect such. But this need not disturb him, because he does not wish to shelter himself beneath them, but looks out for the fair field of practical philosophy, where he may hope to find firmer ground for erecting his own rational and beneficial system.

There is, therefore, no room for real polemic in the sphere of pure reason. Both parties beat the air and fight with their own shadows, because they go beyond the limits of nature, where there is nothing that they could lay hold of with their dogmatical grasp. They may fight to their hearts’ content, the shadows which they are cleaving grow together again in one moment, like the heroes in Valhalla, in order to disport themselves once more in these bloodless contests.

Nor can we admit a sceptical use of pure reason, which might be called the principle of neutrality in all its disputes. Surely, to stir up reason against itself, to supply it with weapons on both sides, and then to look on quietly and scoffingly while the fierce battle is raging, does not look well from a dogmatical point of view, but has the appearance of a mischievous and malevolent disposition. If, however, we consider the invincible [p. 757] obstinacy and the boasting of the dogmatical sophists, who are deaf to all the warnings of criticism, there really seems nothing left but to meet the boasting on one side by an equally justified boasting on the other, in order at least to startle reason by a display of opposition, and thus to shake her confidence and make her willing to listen to the voice of criticism. But to stop at this point, and to look upon the conviction and confession of ignorance, not only as a remedy against dogmatical conceit, but as the best means of settling the conflict of reason with herself, is a vain attempt that will never give rest and peace to reason. The utmost it can do is to rouse reason from her sweet dogmatical dreams, and to induce her to examine more carefully her own position. As, however, the sceptical manner of avoiding a troublesome business seems to be the shortest way out of all difficulties, and promises to lead to a permanent peace in philosophy, or is chosen at least as the highroad by all who, under the pretence of a scornful dislike of all investigations of this kind, try to give themselves the air of philosophers, it seems necessary to exhibit this mode of thought in its true light.

The Impossibility of a Sceptical Satisfaction of Pure Reason in Conflict with itself [p. 758]

The consciousness of my ignorance (unless we recognise at the same time its necessity) ought, instead of forming the end of my investigations, to serve, on the contrary, as their strongest impulse. All ignorance is either an ignorance of things, or an ignorance of the limits of our cognition. If ignorance is accidental, it should incite us, in the former case, to investigate things dogmatically, in the latter to investigate the limits of possible knowledge critically. That my ignorance is absolutely necessary and that I am absolved from the duty of all further investigation, can never be established empirically by mere observation, but critically only, by a thorough examination of the first sources of our knowledge. The determination of the true limits of our reason, therefore, can be made on a priori grounds only, while its limitation, which consists in a general recognition of our never entirely removable ignorance, may be realised a posteriori also, by seeing how much remains to be known in spite of all that can be known. The former knowledge of our ignorance, possible only by criticism of reason, is truly scientific, the latter is merely matter of experience, [p. 759] where it is never possible to say how far the inferences drawn from it may reach. If I regard the earth, according to the evidence of my senses, as a flat surface, I cannot tell how far it may extend. But what experience teaches me is, that wheresoever I go, I always see before me a space in which I can proceed further. Thus I am conscious of the limits of my actual knowledge of the earth at any given moment, but not of the limits of all possible geography. But if I have got so far as to know that the earth is a sphere and its surface spherical, I am able from any small portion of it, for instance, from a degree, to know definitely and according to principles a priori, the diameter, and through it, the complete periphery of the earth; and, though I am ignorant with regard to the objects which are contained in that surface, I am not so with regard to its extent, its magnitude, and its limits.

In a similar manner the whole of the objects of our knowledge appears to us like a level surface, with its apparent horizon which encircles its whole extent, and was called by us the idea of unconditioned totality. To reach this limit empirically is impossible, and all attempts have proved vain to determine it a priori according to a certain principle. Nevertheless, all questions of pure reason refer to what lies outside of that horizon, or, it may be, on its boundary line. [p. 760]

The celebrated David Hume was one of those geographers of human reason who supposed that all those questions were sufficiently disposed of by being relegated outside that horizon, which, however, he was not able to determine. He was chiefly occupied with the principle of causality, and remarked quite rightly, that the truth of this principle (and even the objective validity of the concept of an efficient cause in general) was based on no knowledge, i.e. on no cognition a priori, and that its authority rested by no means on the necessity of such a law, but merely on its general usefulness in experience, and on a kind of subjective necessity arising from thence, which he called habit. From the inability of reason to employ this principle beyond the limits of experience he inferred the nullity of all the pretensions of reason in her attempts to pass beyond what is empirical.

This procedure of subjecting the facts of reason to examination, and, if necessary, to blame, may be termed the censorship of reason. There can be no doubt that such a censorship must inevitably lead to doubts [p. 761] against all the transcendental employment of such principles. But this is only the second and by no means the last step in our enquiry. The first step in matters of pure reason, which marks its infancy, is dogmatism. The second, which we have just described, is scepticism, and marks the stage of caution on the part of reason, when rendered wiser by experience. But a third step is necessary, that of the maturity and manhood of judgment, based on firm and universally applicable maxims, when not the facts of reason, but reason itself in its whole power and fitness for pure knowledge a priori comes to be examined. This is not the censura merely, but the true criticism of reason, by which not the barrier only, but the fixed frontiers of reason, not ignorance only on this or that point, but ignorance with reference to all possible questions of a certain kind, must be proved from principles, instead of being merely guessed at. Thus scepticism is a resting-place of reason, where it may reflect for a time on its dogmatical wanderings and gain a survey of the region where it happens to be, in order to choose its way with greater certainty for the future: but it can never be its permanent dwelling-place. That can only be found in perfect certainty, whether of our knowledge of the objects themselves or of the limits within which all our knowledge of objects is enclosed. [p. 762]

Our reason is not to be considered as an indefinitely extended plain, the limits of which are known in a general way only, but ought rather to be compared to a sphere the radius of which may be determined from the curvature of the arc of its surface (corresponding to the nature of synthetical propositions a priori), which enables us likewise to fix the extent and periphery of it with perfect certainty. Outside that sphere (the field of experience) nothing can become an object to our reason, nay, questions even on such imaginary objects relate to the subjective principles only for a complete determination of all the relations which may exist between the concepts of the understanding within that sphere.

It is a fact that we are in possession of different kinds of synthetical knowledge a priori, as shown by the principles of the understanding which anticipate experience. If anybody finds it quite impossible to understand the possibility of such principles, he may at first have some doubts as to whether they really dwell within us a priori; but he cannot thus, by the mere powers of the understanding, prove their impossibility, and declare all the steps which reason takes under their guidance as null and void. All he can say is that, if we could understand their origin and genuineness, we should be able to determine the extent and limits of our reason, and that, until that is done, all the [p. 763] assertions of reason are made at random. And in this way a complete scepticism with regard to all dogmatical philosophy, which is not guided by a criticism of reason, is well grounded, though we could not therefore deny to reason such further advance, after the way has once been prepared and secured on firmer ground. For all these concepts, nay, all the questions which pure reason places before us, have their origin, not in experience, but in reason itself, and must therefore be capable of being solved and tested as to their validity or invalidity. Nor are we justified, while pretending that the solution of these problems is really to be found in the nature of things, to decline their consideration and further investigation, under the pretext of our weakness, for reason alone begets all these ideas by itself, and is bound therefore to give an account of their validity or their dialectical vanity.

All sceptical polemic should properly be directed against the dogmatist only who, without any misgivings about his own fundamental objective principles, that is, without criticism, continues his course with undisturbed gravity, and should be intended only to unsettle his brief and to bring him thus to a proper self-knowledge. With regard to what we know or what we cannot know, that polemic is of no consequence whatever. All the unsuccessful dogmatical attempts of reason are facta, and it is always [p. 764] useful to submit them to the censura of the sceptic. But this can decide nothing as to the expectations of reason in her hopes and claims of a better success in future attempts; and no mere censura can put an end to the disputes regarding the rights of human reason.

Hume is, perhaps, the most ingenious of all sceptics, and without doubt the most important with regard to the influence which the sceptical method may exercise in awakening reason to a thorough examination of its rights. It will therefore be worth our while to make clear to ourselves the course of his reasoning and the errors of an intelligent and estimable man, who at the outset of his enquiries was certainly on the right track of truth.

Hume was probably aware, though he never made it quite clear to himself, that in judgments of a certain kind we pass beyond our concept of the object. I have called this class of judgments synthetical. There is no difficulty as to how I may, by means of experience, pass beyond the concept which I have hitherto had. Experience is itself such a synthesis of perceptions through which a concept, which I have by means of one perception, is increased by means of other perceptions. But we imagine that we are able also a priori to pass beyond our concept [p. 765] and thus to enlarge our knowledge. This we attempt to do either by the pure understanding, in relation to that which can at least be an object of experience, or even by means of pure reason, in relation to such qualities of things, or even the existence of such things, as can never occur in experience. Hume in his scepticism did not distinguish between these two kinds of judgments as he ought to have done, but regarded this augmentation of concepts by themselves, and, so to say, the spontaneous generation of our understanding (and of our reason), without being impregnated by experience, as perfectly impossible. Considering all principles a priori as imaginary, he arrived at the conclusion that they were nothing but a habit arising from experience and its laws; that they were therefore merely empirical, that is, in themselves, contingent rules to which we wrongly ascribe necessity and universality. In order to establish this strange proposition, he appealed to the generally admitted principle of the relation between cause and effect. For as no faculty of the understanding could lead us from the concept of a thing to the existence of something else that should follow from it universally and necessarily, he thought himself justified in concluding that, without experience, we have nothing that could augment our concept and give us a right to form a judgment that extends itself a priori. That the light of the sun which shines on the wax should melt the wax and at the same time harden the clay, no understanding, [p. 766] he maintained, could guess from the concepts which we had before of these things, much less infer, according to a law, experience only being able to teach us such a law. We have seen, on the contrary, in the transcendental logic that, though we can never pass immediately beyond the content of a concept that is given us, we are nevertheless able, entirely a priori, but yet in reference to something else, namely, possible experience, to know the law of its connection with other things. If, therefore, wax, which was formerly hard, melts, I can know a priori that something else must have preceded (for instance the heat of the sun) upon which this melting has followed according to a permanent law, although without experience I could never know a priori definitely either from the effect the cause, or from the cause the effect. Hume was therefore wrong in inferring from the mere contingency of our being determined according to the law of causality, the contingency of that law itself, and he mistook our passing beyond the concept of a thing to some possible experience (which is entirely a priori and constitutes the objective reality of it) for the synthesis of the objects of real experience which, no doubt, is always empirical. He thus changed a principle of affinity which resides in the understanding and predicates necessary connection, into a rule of association residing in the imitative faculty of imagination, which can only represent contingent, but [p. 767] never objective connections.

The sceptical errors of that otherwise singularly acute thinker arose chiefly from a defect, which he shared, however, in common with all dogmatists, namely, of not having surveyed systematically all kinds of synthesis a priori of the understanding. For in doing this he would, without mentioning others, have discovered, for instance, the principle of permanency as one which, like causality, anticipates experience. He would thus have been able also to fix definite limits to the understanding in its attempts at expansion a priori and to pure reason. He only narrows the sphere of our understanding, without definitely limiting it, and produces a general mistrust, but no definite knowledge of that ignorance which to us is inevitable. He only subjects certain principles of the understanding to his censura, but does not place the understanding, with reference to all its faculties, on the balance of criticism. He is not satisfied with denying to the understanding what in reality it does not possess, but goes on to deny to it all power of expanding a priori, though he has never really tested all its powers. For this reason, what always defeats scepticism has happened to Hume also, namely, that he himself becomes subject to scepticism, because his objections rest on facts only which are contingent, and not on principles which alone can force a surrender of the right of dogmatical assertion. [p. 768]

As, besides this, he does not sufficiently distinguish between the well-grounded claims of the understanding and the dialectical pretensions of reason, against which, however, his attacks are chiefly directed, it so happens that reason, the peculiar tendency of which has not in the least been destroyed, but only checked, does not at all consider itself shut out from its attempts at expansion, and can never be entirely turned away from them, although it may be punished now and then. Mere attacks only provoke counter attacks, and make us more obstinate in enforcing our own views. But a complete survey of all that is really our own, and the conviction of a certain though a small possession, make us perceive the vanity of higher claims, and induce us, after surrendering all disputes, to live contentedly and peacefully within our own limited, but undisputed domain.

These sceptical attacks are not only dangerous, but even destructive to the uncritical dogmatist who has not measured the sphere of his understanding, and has not, therefore, determined, according to principles, the limits of his own possible knowledge, and does not know beforehand how much he is really able to achieve, but thinks that he is able to find all this out by a purely tentative method. For if he has been found out in one single assertion of his, which he cannot justify, or the fallacy of which he cannot evolve according to principles, [p. 769] suspicion falls on all his assertions, however plausible they may appear.

And thus the sceptic is the true schoolmaster to lead the dogmatic speculator towards a sound criticism of the understanding and of reason. When he has once been brought there, he need fear no further attacks, for he has learnt to distinguish his own possession from that which lies completely beyond it, and on which he can lay no claim, nor become involved in any disputes regarding it. Thus the sceptical method, though it cannot in itself satisfy with regard to the problems of reason, is nevertheless an excellent preparation in order to awaken its circumspection, and to indicate the true means whereby the legitimate possessions of reason may be secured against all attacks.