The Critique of Practical Reason - Immanuel Kant (classic books to read .txt) 📗

as regards the object, but a necessary supposition as regards the subject, necessary for the obedience to its objective but practical laws. It is, therefore, merely a necessary hypothesis. I could find no better expression for this rational necessity, which is subjective, but yet true and unconditional.

In this manner, then, the a priori principles of two faculties of the mind, the faculty of cognition and that of desire, would be found and determined as to the conditions, extent, and limits of their use, and thus a sure foundation be paid for a scientific system of philosophy, both theoretic and practical.

Nothing worse could happen to these labours than that anyone should make the unexpected discovery that there neither is, nor can be, any a priori knowledge at all. But there is no danger of this.

This would be the same thing as if one sought to prove by reason that there is no reason. For we only say that we know something by reason, when we are conscious that we could have known it, even if it had not been given to us in experience; hence rational knowledge and knowledge a priori are one and the same. It is a clear contradiction to try to extract necessity from a principle of experience (ex pumice aquam), and to try by this to give a judgement true universality (without which there is no rational inference, not even inference from analogy, which is at least a presumed universality and objective necessity). To substitute subjective necessity, that is, custom, for objective, which exists only in a priori judgements, is to deny to reason the power of judging about the object, i.e., of knowing it, and what belongs to it. It implies, for example, that we must not say of something which often or always follows a certain antecedent state that we can conclude from this to that (for this would imply objective necessity and the notion of an a priori connexion), but only that we may expect similar cases (just as animals do), that is that we reject the notion of cause altogether as false and a mere delusion. As to attempting to remedy this want of objective and consequently universal validity by saying that we can see no ground for attributing any other sort of knowledge to other rational beings, if this reasoning were valid, our ignorance would do more for the enlargement of our knowledge than all our meditation. For, then, on this very ground that we have no knowledge of any other rational beings besides man, we should have a right to suppose them to be of the same nature as we know ourselves to be: that is, we should really know them. I omit to mention that universal assent does not prove the objective validity of a judgement (i.e., its validity as a cognition), and although this universal assent should accidentally happen, it could furnish no proof of agreement with the object; on the contrary, it is the objective validity which alone constitutes the basis of a necessary universal consent.

{PREFACE ^paragraph 30}

Hume would be quite satisfied with this system of universal empiricism, for, as is well known, he desired nothing more than that, instead of ascribing any objective meaning to the necessity in the concept of cause, a merely subjective one should be assumed, viz., custom, in order to deny that reason could judge about God, freedom, and immortality; and if once his principles were granted, he was certainly well able to deduce his conclusions therefrom, with all logical coherence. But even Hume did not make his empiricism so universal as to include mathematics. He holds the principles of mathematics to be analytical; and if his were correct, they would certainly be apodeictic also: but we could not infer from this that reason has the faculty of forming apodeictic judgements in philosophy also-that is to say, those which are synthetical judgements, like the judgement of causality. But if we adopt a universal empiricism, then mathematics will be included.

Now if this science is in contradiction with a reason that admits only empirical principles, as it inevitably is in the antinomy in which mathematics prove the infinite divisibility of space, which empiricism cannot admit; then the greatest possible evidence of demonstration is in manifest contradiction with the alleged conclusions from experience, and we are driven to ask, like Cheselden’s blind patient, “Which deceives me, sight or touch?” (for empiricism is based on a necessity felt, rationalism on a necessity seen). And thus universal empiricism reveals itself as absolute scepticism. It is erroneous to attribute this in such an unqualified sense to Hume, * since he left at least one certain touchstone (which can only be found in a priori principles), although experience consists not only of feelings, but also of judgements.

* Names that designate the followers of a sect have always been accompanied with much injustice; just as if one said, “N is an Idealist.” For although he not only admits, but even insists, that our ideas of external things have actual objects of external things corresponding to them, yet he holds that the form of the intuition does not depend on them but on the human mind.

{PREFACE ^paragraph 35}

However, as in this philosophical and critical age such empiricism can scarcely be serious, and it is probably put forward only as an intellectual exercise and for the purpose of putting in a clearer light, by contrast, the necessity of rational a priori principles, we can only be grateful to those who employ themselves in this otherwise uninstructive labour.

INTRODUCTION

INTRODUCTION.

Of the Idea of a Critique of Practical Reason.

The theoretical use of reason was concerned with objects of the cognitive faculty only, and a critical examination of it with reference to this use applied properly only to the pure faculty of cognition; because this raised the suspicion, which was afterwards confirmed, that it might easily pass beyond its limits, and be lost among unattainable objects, or even contradictory notions. It is quite different with the practical use of reason. In this, reason is concerned with the grounds of determination of the will, which is a faculty either to produce objects corresponding to ideas, or to determine ourselves to the effecting of such objects (whether the physical power is sufficient or not); that is, to determine our causality. For here, reason can at least attain so far as to determine the will, and has always objective reality in so far as it is the volition only that is in question. The first question here then is whether pure reason of itself alone suffices to determine the will, or whether it can be a ground of determination only as dependent on empirical conditions. Now, here there comes in a notion of causality justified by the critique of the pure reason, although not capable of being presented empirically, viz., that of freedom; and if we can now discover means of proving that this property does in fact belong to the human will (and so to the will of all rational beings), then it will not only be shown that pure reason can be practical, but that it alone, and not reason empirically limited, is indubitably practical; consequently, we shall have to make a critical examination, not of pure practical reason, but only of practical reason generally. For when once pure reason is shown to exist, it needs no critical examination. For reason itself contains the standard for the critical examination of every use of it. The critique, then, of practical reason generally is bound to prevent the empirically conditioned reason from claiming exclusively to furnish the ground of determination of the will. If it is proved that there is a [practical] reason, its employment is alone immanent; the empirically conditioned use, which claims supremacy, is on the contrary transcendent and expresses itself in demands and precepts which go quite beyond its sphere. This is just the opposite of what might be said of pure reason in its speculative employment.

However, as it is still pure reason, the knowledge of which is here the foundation of its practical employment, the general outline of the classification of a critique of practical reason must be arranged in accordance with that of the speculative. We must, then, have the Elements and the Methodology of it; and in the former an Analytic as the rule of truth, and a Dialectic as the exposition and dissolution of the illusion in the judgements of practical reason. But the order in the subdivision of the Analytic will be the reverse of that in the critique of the pure speculative reason. For, in the present case, we shall commence with the principles and proceed to the concepts, and only then, if possible, to the senses; whereas in the case of the speculative reason we began with the senses and had to end with the principles. The reason of this lies again in this: that now we have to do with a will, and have to consider reason, not in its relation to objects, but to this will and its causality. We must, then, begin with the principles of a causality not empirically conditioned, after which the attempt can be made to establish our notions of the determining grounds of such a will, of their application to objects, and finally to the subject and its sense faculty. We necessarily begin with the law of causality from freedom, that is, with a pure practical principle, and this determines the objects to which alone it can be applied.

BOOK_1|CHAPTER_1

FIRST PART.

ELEMENTS OF PURE PRACTICAL REASON.

BOOK I. The Analytic of Pure Practical Reason.

CHAPTER I. Of the Principles of Pure Practical Reason.

{BOOK_1|CHAPTER_1 ^paragraph 5}

I. DEFINITION.

Practical principles are propositions which contain a general determination of the will, having under it several practical rules.

They are subjective, or maxims, when the condition is regarded by the subject as valid only for his own will, but are objective, or practical laws, when the condition is recognized as objective, that is, valid for the will of every rational being.

{BOOK_1|CHAPTER_1 ^paragraph 10}

REMARK.

Supposing that pure reason contains in itself a practical motive, that is, one adequate to determine the will, then there are practical laws; otherwise all practical principles will be mere maxims. In case the will of a rational being is pathologically affected, there may occur a conflict of the maxims with the practical laws recognized by itself. For example, one may make it his maxim to let no injury pass unrevenged, and yet he may see that this is not a practical law, but only his own maxim; that, on the contrary, regarded as being in one and the same maxim a rule for the will of every rational being, it must contradict itself. In natural philosophy the principles of what happens, e.g., the principle of equality of action and reaction in the communication of motion) are at the same time laws of nature; for the use of reason there is theoretical and determined by the nature of the object. In practical philosophy, i.e., that which has to do only with the grounds of determination of the will, the principles which a man makes for himself are not laws by which one is inevitably bound; because reason in practical matters has to do with the subject, namely, with the faculty of desire, the special character of which may occasion variety in the rule. The practical rule is always a product of reason, because it prescribes action as a means to the effect. But in the case of a being with whom reason does not of itself determine the will, this rule is an imperative, i.e., a rule characterized by “shall,”

which expresses the objective necessitation of the action and signifies that, if reason completely determined the will, the action would inevitably take place according to this rule. Imperatives, therefore, are objectively valid, and are quite