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Free Will
Mental Causation
James Symposium
Critique of Practical Reason
(Thomas Kingsmill Abbott translation, Britannica Great Books edition)
Preface (pp. 291-293)
This work is called the Critique of Practical Reason, not of the pure practical reason, although its parallelism with the speculative critique would seem to require the latter term. The reason of this appears sufficiently from the treatise itself. Its business is to show that there is pure practical reason, and for this purpose it criticizes the entire practical faculty of reason. If it succeeds in this, it has no need to criticize the pure faculty itself in order to see whether reason in making such a claim does not presumptuously overstep itself (as is the case with the speculative reason). For if, as pure reason, it is actually practical, it proves its own reality and that of its concepts by fact, and all disputation against thee possibility of its being real is futile.

With this faculty, transcendental freedom is also established; freedom, namely, in that absolute sense in which speculative reason required it in its use of the concept of causality in order to escape the antinomy into which it inevitably falls, when in the chain of cause and effect it tries to think the unconditioned.

Hume claimed we could not know, but could not deny the possibility of concepts like causality

Kant claims that speculative reason cannot deny the possibility of freedom, which is a condition for the moral law

Speculative reason could only exhibit this concept (of freedom) problematically as not impossible to thought, without assuring it any objective reality, and merely lest the supposed impossibility of what it must at least allow to be thinkable should endanger its very being and plunge it into an abyss of skepticism.

Inasmuch as the reality of the concept of freedom is proved by an apodeictic law of practical reason, it is the keystone of the whole system of pure reason, even the speculative, and all other concepts (those of God and immortality) which, as being mere ideas, remain in it unsupported, now attach themselves to this concept, and by it obtain consistence and objective reality; that is to say, their possibility is proved by the fact that freedom actually exists, for this idea is revealed by the moral law.

Freedom, however, is the only one of all the ideas of the speculative reason of which we know the possibility a priori (without, however, understanding it), because it is the condition of the moral law which we know.1

The ideas of God and immortality, however, are not conditions of the moral law, but only conditions of the necessary object of a will determined by this law; that is to say, conditions of the practical use of our pure reason.
Here Kant has adopted Hume's skeptical position on knowledge by pure speculative reason. Hume's natural (moral) belief, for example, in causality, corresponds to Kant's practical (moral) reason.
Hence, with respect to these ideas, we cannot affirm that we know and understand, I will not say the actuality, but even the possibility of them. However they are the conditions of the application of the morally determined will to its object, which is given to it a priori, viz., the summum bonum. Consequently in this practical point of view their possibility must be assumed, although we cannot theoretically know and understand it. To justify this assumption it is sufficient, in a practical point of view, that they contain no intrinsic impossibility (contradiction).

Where Hume asserted we had a natural (moral) belief in causality, Kant asserts the practical need for freedom
Here we have what, as far as speculative reason is concerned, is a merely subjective principle of assent, which, however, is objectively valid for a reason equally pure but practical, and this principle, by means of the concept of freedom, assures objective reality and authority to the ideas of God and immortality. Nay, there is a subjective necessity (a need of pure reason) to assume them. Nevertheless the theoretical knowledge of reason is not hereby enlarged, but only the possibility is given, which heretofore was merely a problem and now becomes assertion, and thus the practical use of reason is connected with the elements of theoretical reason. And this need is not a merely hypothetical one for the arbitrary purposes of speculation, that we must assume something if we wish in speculation to carry reason to its utmost limits, but it is a need which has the force of law to assume something without which that cannot be which we must inevitably set before us as the aim of our action.

It would certainly be more satisfactory to our speculative reason if it could solve these problems for itself without this circuit and preserve the solution for practical use as a thing to be referred to, but in fact our faculty of speculation is not so well provided. Those who boast of such high knowledge ought not to keep it back, but to exhibit it publicly that it may be tested and appreciated. They want to prove: very good, let them prove; and the critical philosophy lays its arms at their feet as the victors. Quid static? Nolint. Atqui licet esse beatis. As they then do not in fact choose to do so, probably because they cannot, we must take up these arms again in order to seek in the mortal use of reason, and to base on this, the notions of God, freedom, and immortality, the possibility of which speculation cannot adequately prove.

Here first is explained the enigma of the critical philosophy, viz.: how we deny objective reality to the supersensible use of the categories in speculation and yet admit this reality with respect to the objects of pure practical reason. This must at first seem inconsistent as long as this practical use is only nominally known. But when, by a thorough analysis of it, one becomes aware that the reality spoken of does not imply any theoretical determination of the categories and extension of our knowledge to the supersensible; but that what is meant is that in this respect an object belongs to them, because either they are contained in the necessary determination of the will a priori, or are inseparably connected with its object; then this inconsistency disappears, because the use we make of these concepts is different from what speculative reason requires. On the other hand, there now appears an unexpected and very satisfactory proof of the consistency of the speculative critical philosophy. For whereas it insisted that the objects of experience as such, including our own subject, have only the value of phenomena, while at the same time things in themselves must be supposed as their basis, so that not everything supersensible was to be regarded as a fiction and its concept as empty; so now practical reason itself, without any concert with the speculative, assures reality to a super-sensible object of the category of causality, viz., freedom, although (as becomes a practical concept) only for practical use; and this establishes on the evidence of a fact that which in the former case could only be conceived. By this the strange but certain doctrine of the speculative critical philosophy, that the thinking subject is to itself in internal intuition only a phenomenon, obtains in the critical examination of practical reason its full confirmation, and this so thoroughly that we should be compelled to adopt this doctrine, even if the former had never proved it at all.1

By this also I can understand why the most considerable objections which I have as yet with against the Critique turn about these two points, namely, on the one side, the objective reality of the categories as applied to noumena, which is in the theoretical department of knowledge denied, in the practical affirmed; and on the other side, the paradoxical demand to regard oneself qua subject of freedom as a noumenon, and at the same time from the point of view physical nature as a phenomenon in one's empirical consciousness; for as long as one formed no definite notions of morality and freedom, one could not conjecture on the side what what was intended to be the noumenon, basis of the alleged phenomenon, and on other side it seemed doubtful whether it was all possible to form any notion of it, seeing that we had previously assigned all the notions of the pure understanding in its theoretical use exclusively to phenomena. Nothing but a detailed criticism of the practical reason can remove all this misapprehension and set in a clear light the consistency which constitutes its greatest merit.

So much by way of justification of the proceeding by which, in this work, the notions and principles of pure speculative reason which have already undergone their special critical examination are, now and then, again subjected to examination. This would not in other cases be in accordance with the systematic process by which a science is established, since matters which have been decided ought only to be cited and not again discussed. In this case, however, it was not only allowable but necessary, because reason is here considered in transition to a different use of these concepts from what it had made of them before. Such a transition necessitates a comparison of the old and the new usage, in order to distinguish well the new path from the old one and, at the same time, to allow their connection to be observed. Accordingly considerations of this kind, including those which are once more directed to the concept of freedom in the practical use of the pure reason, must not be regarded as an interpolation serving only to fill up the gaps in the critical system of speculative reason (for this is for its own purpose complete), or like the props and buttresses which in a hastily constructed building are often added afterwards; but as true members which make the connexion of the system plain, and show us concepts, here presented as real, which there could only be presented problematically.

Hume made causality a natural belief and moral sentiment beyond empirical reason, Kant makes freedom one in his noumenal realm beyond pure speculative reason to establish the moral law
This remark applies especially to the concept of freedom, respecting which one cannot but observe with surprise that so many boast of being able to understand it quite well and to explain its possibility, while they regard it only psychologically, whereas if they had studied it in a transcendental point of view, they must have recognized that it is not only indispensable as a problematical concept, in the complete use of speculative reason, but also quite incomprehensible; and if they afterwards came to consider its practical use, they must needs have come to the very mode of determining the principles of this to which they are now so loth to assent. The concept of freedom is the stone of stumbling for all empiricists, but at the same time the key to the loftiest practical principles for critical moralists, who perceive by its means that they must necessarily proceed by a rational method. For this reason I beg the reader not to pass lightly over what is said of this concept at the end of the Analytic.

I must leave it to those who are acquainted with works of this kind to judge whether such a system as that of the practical reason, which is here developed from the critical examination of it, has cost much or little trouble, especially in seeking not to miss the true point of view from which the whole can be rightly sketched. It presupposes, indeed, the Fundamental Principles of the Metaphysic of Morals, but only in so far as this gives a preliminary acquaintance with the principle of duty, and assigns and justifies a definite formula thereof; in other respects it is independent.1

Kant refers to Hume's project for a "science of man"
It results from the nature of this practical faculty itself that the complete classification of all practical sciences cannot be added, as in the critique of the speculative reason. For it is not possible to define duties specially, as human duties, with a view to their classification, until the subject of this definition (viz., man) is known according to his actual nature, at least so far as is necessary with respect to duty; this, however, does not belong to a critical examination of the practical reason, the business of which is only to assign in a complete manner the principles of its possibility, extent, and limits, without special reference to human nature. The classification then belongs to the system of science, not to the system of criticism.
Critical Examination of the Analytic of Pure Practical Reason
(pp. 329-337)
By the critical examination of a science, or of a portion of it, which constitutes a system by itself, I understand the inquiry and proof why it must have this and no other systematic form, when we compare it with another system which is based on a similar faculty of knowledge. Now practical and speculative reason are based on the same faculty, so far as both are pure reason. Therefore the difference in their systematic form must be determined by the comparison of both, and the ground of this must be assigned.

The Analytic of pure theoretic reason had to do with the knowledge of such objects as may have been given to the understanding, and was obliged therefore to begin from intuition [Anschauung] and consequently (as this is always sensible) from sensibility; and only after that could advance to concepts (of the objects of this intuition), and could only end with principles after both these had preceded. On the contrary, since practical reason has not to do with objects so as to know them, but with its own faculty of realizing them (in accordance with the knowledge of them), that is, with a will which is a causality, inasmuch as reason contains its determining principle; since, consequently, it has not to furnish an object of intuition, but as practical reason has to furnish only a law (because the notion of causality always implies the reference to a law which determines the existence of the many in relation to one another); hence a critical examination of the Analytic of reason, if this is to be practical reason (and this is properly the problem), must begin with the possibility of practical principles a priori.

Kant here makes the explicit connection between his Practical Reason and Hume's Moral Sentiment
Only after that can it proceed to concepts of the objects of a practical reason, namely, those of absolute good and evil, in order to assign them is accordance with those principles (for prior to those principles they cannot possibly be given as good and evil by any faculty of knowledge), and only then could the section be concluded with the last chapter, that, namely, which treats of the relation of the pure practical reason to the sensibility and of its necessary influence thereon, which is a priori cognisable, that is, of the moral sentiment [moralische Gefühle].

Thus the Analytic of the practical pure reason has the whole extent of the conditions of its use in common with the theoretical, but in reverse order. The Analytic of pure theoretic reason was divided into transcendental Aesthetic and transcendental Logic, that of the practical reversely into Logic and Aesthetic of pure practical reason (if I may, for the sake of analogy merely, use these designations, which are not quite suitable). This logic again was there divided into the Analytic of concepts and that of principles: here into that of principles and concepts.

Kant's pure practical Aesthetic is identified with Hume's feeling.
The Aesthetic also had in the former case two parts, on account of the two kinds of sensible intuition; here the sensibility is not considered as a capacity of intuition at all, but merely as feeling (which can be a subjective ground of desire), and in regard to it pure practical reason admits no further division.

It is also easy to see the reason why this division into two parts with its subdivision was not actually adopted here (as one might have been induced to attempt by the example of the former critique). For since it is pure reason that is here considered in its practical use, and consequently as proceeding from a priori principles, and not from empirical principles of determination, hence the division of the analytic of pure practical reason must resemble that of a syllogism; namely, proceeding from the universal in the major premiss (the moral principle), through a minor premiss containing a subsumption of possible actions (as good or evil) under the former, to the conclusion, namely, the subjective determination of the will (an interest in the possible practical good, and in the maxim founded on it). He who has been able to convince himself of the truth of the positions occurring in the Analytic will take pleasure in such comparisons; for they justly suggest the expectation that we may perhaps some day be able to discern the unity of the whole faculty of reason (theoretical as well as practical) and be able to derive all from one principle, which is what human reason inevitably demands, as it finds complete satisfaction only in a perfectly systematic unity of its knowledge.

If now we consider also the contents of the knowledge that we can have of a pure practical reason, and by means of it, as shown by the Analytic, we find, along with a remarkable analogy between it and the theoretical, no less remarkable differences. As regards the theoretical, the faculty of a pure rational cognition a priori could be easily and evidently proved by examples from sciences (in which, as they put their principles to the test in so many ways by methodical use, there is not so much reason as in common knowledge to fear a secret mixture of empirical principles of cognition). But, that pure reason without the admixture of any empirical principle is practical of itself, this could only be shown from the commonest practical use of reason, by verifying the fact, that every man's natural reason acknowledges the supreme practical principle as the supreme law of his will — a law completely a priori and not depending on any sensible data. It was necessary first to establish and verify the purity of its origin, even in the judgement of this common reason, before science could take it in hand to make use of it, as a fact, that is, prior to all disputation about its possibility, and all the consequences that may be drawn from it. But this circumstance may be readily explained from what has just been said; because practical pure reason must necessarily begin with principles, which therefore must be the first data, the foundation of all science, and cannot be derived from it. It was possible to effect this verification of moral principles as principles of a pure reason quite well, and with sufficient certainty, by a single appeal to the judgement of common sense, for this reason, that anything empirical which might slip into our maxims as a determining principle of the will can be detected at once by the feeling of pleasure or pain which necessarily attaches to it as exciting desire; whereas pure practical reason positively refuses to admit this feeling into its principle as a condition. The heterogeneity of the determining principles (the empirical and rational) is clearly detected by this resistance of a practically legislating reason against every admixture of inclination, and by a peculiar kind of sentiment, which, however, does not precede the legislation of the practical reason, but, on the contrary, is produced by this as a constraint, namely, by the feeling of a respect such as no man has for inclinations of whatever kind but for the law only; and it is detected in so marked and prominent a manner that even the most uninstructed cannot fail to see at once in an example presented to him, that empirical principles of volition may indeed urge him to follow their attractions, but that he can never be expected to obey anything but the pure practical law of reason alone.

The distinction between the doctrine of happiness and the doctrine of morality, in the former of which empirical principles constitute the entire foundation, while in the second they do not form the smallest part of it, is the first and most important office of the Analytic of pure practical reason; and it must proceed in it with as much exactness and, so to speak, scrupulousness, as any geometer in his work. The philosopher, however, has greater difficulties to contend with here (as always in rational cognition by means of concepts merely without construction), because he cannot take any intuition as a foundation (for a pure noumenon). He has, however, this advantage that, like the chemist, he can at any time make an experiment with every man's practical reason for the purpose of distinguishing the moral (pure) principle of determination from the empirical: namely, by adding the moral law (as a determining principle) to the empirically affected will (e.g., that of the man who would be ready to lie because he can gain something thereby). It is as if the analyst added alkali to a solution of lime in hydrochloric acid, the acid at once forsakes the lime, combines with the alkali, and the lime is precipitated. Just in the same way, if to a man who is otherwise honest (or who for this occasion places himself only in thought in the position of an honest man), we present the moral law by which he recognises the worthlessness of the liar, his practical reason (in forming a judgement of what ought to be done) at once forsakes the advantage, combines with that which maintains in him respect for his own person (truthfulness), and the advantage after it has been separated and washed from every particle of reason (which is altogether on the side of duty) is easily weighed by everyone, so that it can enter into combination with reason in other cases, only not where it could be opposed to the moral law, which reason never forsakes, but most closely unites itself with.

But it does not follow that this distinction between the principle of happiness and that of morality is an opposition between them, and pure practical reason does not require that we should renounce all claim to happiness, but only that the moment duty is in question we should take no account of happiness. It may even in certain respects be a duty to provide for happiness; partly, because (including skill, wealth, riches) it contains means for the fulfilment of our duty; partly, because the absence of it (e.g., poverty) implies temptations to transgress our duty. But it can never be an immediate duty to promote our happiness, still less can it be the principle of all duty. Now, as all determining principles of the will, except the law of pure practical reason alone (the moral law), are all empirical and, therefore, as such, belong to the principle of happiness, they must all be kept apart from the supreme principle of morality and never be incorporated with it as a condition; since this would be to destroy all moral worth just as much as any empirical admixture with geometrical principles would destroy the certainty of mathematical evidence, which in Plato's opinion is the most excellent thing in mathematics, even surpassing their utility.

Instead, however, of the deduction of the supreme principle of pure practical reason, that is, the explanation of the possibility of such a knowledge a priori, the utmost we were able to do was to show that if we saw the possibility of the freedom of an efficient cause, we should also see not merely the possibility, but even the necessity, of the moral law as the supreme practical law of rational beings, to whom we attribute freedom of causality of their will; because both concepts are so inseparably united that we might define practical freedom as independence of the will on anything but the moral law. But we cannot perceive the possibility of the freedom of an efficient cause, especially in the world of sense; we are fortunate if only we can be sufficiently assured that there is no proof of its impossibility, and are now, by the moral law which postulates it, compelled and therefore authorized to assume it. However, there are still many who think that they can explain this freedom on empirical principles, like any other physical faculty, and treat it as a psychological property, the explanation of which only requires a more exact study of the nature of the soul and of the motives of the will, and not as a transcendental predicate of the causality of a being that belongs to the world of sense (which is really the point). They thus deprive us of the grand revelation which we obtain through practical reason by means of the moral law, the revelation, namely, of a supersensible world by the realization of the otherwise transcendent concept of freedom, and by this deprive us also of moral law itself, which admits no empirical principle of determination. Therefore it will be necessary to add something here as a protection against this delusion and to exhibit empiricism in its naked superficiality.

The notion of causality as physical necessity, in opposition to the same notion as freedom, concerns only the existence of things so far as it is determinable in time, and, consequently, as phenomena, in opposition to their causality as things in themselves. Now if we take the attributes of existence of things in time for attributes of things in themselves (which is the common view), then it is impossible to reconcile the necessity of the causal relation with freedom; they are contradictory.

Here Kant states the Determinism Objection in the standard argument against free will
For from the former it follows that every event, and consequently every action that takes place at a certain point of time, is a necessary result of what existed in time preceding. Now as time past is no longer in my power, hence every action that I perform must be the necessary result of certain determining grounds which are not in my power, that is, at the moment in which I am acting I am never free. Nay, even if I assume that my whole existence is independent on any foreign cause (for instance, God), so that the determining principles of my causality, and even of my whole existence, were not outside myself, yet this would not in the least transform that physical necessity into freedom. For at every moment of time I am still under the necessity of being determined to action by that which is not in my power, and the series of events infinite a parte priori, which I only continue according to a pre-determined order and could never begin of myself, would be a continuous physical chain, and therefore my causality would never be freedom.

Kant completes the standard argument against free will by saying the alternative to necessity is chance
If, then, we would attribute freedom to a being whose existence is determined in time, we cannot except him from the law of necessity as to all events in his existence and, consequently, as to his actions also; for that would be to hand him over to blind chance. Now as this law inevitably applies to all the causality of things, so far as their existence is determinable in time, it follows that if this were the mode in which we had also to conceive the existence of these things in themselves, freedom must be rejected as a vain and impossible conception.
To save freedom, Kant puts it in a noumenal realm outside of time

He thus reconciles the contradictory concepts of freedom and necessity

Consequently, if we would still save it, no other way remains but to consider that the existence of a thing, so far as it is determinable in time, and therefore its causality, according to the law of physical necessity, belong to appearance, and to attribute freedom to the same being as a thing in itself. This is certainly inevitable, if we would retain both these contradictory concepts together; but in application, when we try to explain their combination in one and the same action, great difficulties present themselves which seem to render such a combination impracticable.

When I say of a man who commits a theft that, by the law of causality, this deed is a necessary result of the determining causes in preceding time, then it was impossible that it could not have happened; how then can the judgement, according to the moral law, make any change, and suppose that it could have been omitted, because the law says that it ought to have been omitted; that is, how can a man be called quite free at the same moment, and with respect to the same action in which he is subject to an inevitable physical necessity? Some try to evade this by saying that the causes that determine his causality are of such a kind as to agree with a comparative notion of freedom. According to this, that is sometimes called a free effect, the determining physical cause of which lies within the acting thing itself, e. g., that which a projectile performs when it is in free motion, in which case we use the word freedom, because while it is in flight it is not urged by anything external; or as we call the motion of a clock a free motion, because it moves its hands itself, which therefore do not require to be pushed by external force; so although the actions of man are necessarily determined by causes which precede in time, we yet call them free, because these causes are ideas produced by our own faculties, whereby desires are evoked on occasion of circumstances, and hence actions are wrought according to our own pleasure.

Kant attacks Hume's compatibilism as a "wretched subterfuge" and his verbal confusion as "word-jugglery"
This is a wretched subterfuge [elender Behelf] with which some persons still let themselves be put off, and so think they have solved, with a petty word-jugglery [Wortklauberei], that difficult problem, at the solution of which centuries have laboured in vain, and which can therefore scarcely be found so completely on the surface. In fact, in the question about the freedom which must be the foundation of all moral laws and the consequent responsibility, it does not matter whether the principles which necessarily determine causality by a physical law reside within the subject or without him, or in the former case whether these principles are instinctive or are conceived by reason, if, as is admitted by these men themselves, these determining ideas have the ground of their existence in time and in the antecedent state, and this again in an antecedent, etc. Then it matters not that these are internal; it matters not that they have a psychological and not a mechanical causality, that is, produce actions by means of ideas and not by bodily movements; they are still determining principles of the causality of a being whose existence is determinable in time, and therefore under the necessitation of conditions of past time, which therefore, when the subject has to act, are no longer in his power. This may imply psychological freedom (if we choose to apply this term to a merely internal chain of ideas in the mind), but it involves physical necessity and, therefore, leaves no room for transcendental freedom, which must be conceived as independence on everything empirical, and, consequently, on nature generally, whether it is an object of the internal sense considered in time only, or of the external in time and space. Without this freedom (in the latter and true sense which alone is practical a priori, no moral law and no moral imputation are possible. Just for this reason the necessity of events in time, according to the physical law of causality, may be called the mechanism of nature, although we do not mean by this that things which are subject to it must be really material machines. We look here only to the necessity of the connection of events in a time-series as it is developed according to the physical law, whether the subject in which this development takes place is called automaton materiale when the mechanical being is moved by matter, or with Leibnitz spirituale when it is impelled by ideas: and if the freedom of our will were no other than the latter (say the psychological and comparative, not also transcendental, that is, absolute), then it would at bottom be nothing better than the freedom of a turnspit, which when once it is wound up, accomplishes its motions of itself.

Kant introduces his own absurd "wretched subterfuge," that agents are determined and necessitated as phenomena but metaphysically free as noumena
Now, in order to remove in the supposed case the apparent contradiction between freedom and the mechanism of nature in one and the same action, we must remember what was said in the Critique of Pure Reason, or what follows therefrom; viz., that the necessity of nature, which cannot co-exist with the freedom of the subject, appertains only to the attributes of the thing that is subject to time-conditions, consequently only to those of the acting subject as a phenomenon; that therefore in this respect the determining principles of every action of the same reside in what belongs to past time and is no longer in his power (in which must be included his own past actions and the character that these may determine for him in his own eyes as a phenomenon). But the very same subject, being on the other side conscious of himself as a thing in himself, considers his existence also in so far as it is not subject to time-conditions, and regards himself as only determinable by laws which he gives himself through reason; and in this his existence nothing is antecedent to the determination of his will, but every action, and in general every modification of his existence, varying according to his internal sense, even the whole series of his existence as a sensible being is in the consciousness of his supersensible existence nothing but the result, and never to be regarded as the determining principle, of his causality as a noumenon. In this view now the rational being can justly say of every unlawful action that he performs, that he could very well have left it undone; although as appearance it is sufficiently determined in the past, and in this respect is absolutely necessary; for it, with all the past which determines it, belongs to the one single phenomenon of his character which he makes for himself, in consequence of which he imputes the causality of :hose appearances to himself as a cause independent of sensibility.

With this agree perfectly the judicial sentences of that wonderful faculty in us which we call conscience. A man may use as much art as he likes in order to paint to himself an unlawful act, that he remembers, as an unintentional error, a mere oversight, such as one can never altogether avoid, and therefore as something in which he was carried away by the stream of physical necessity, and thus to make himself out innocent, yet he finds that the advocate who speaks in his favour can by no means silence the accuser within, if only he is conscious that at the time when he did this wrong he was in his senses, that is, in possession of his freedom; and, nevertheless, he accounts for his error from some bad habits, which by gradual neglect of attention he has allowed to grow upon him to such a degree that he can regard his error as its natural consequence, although this cannot protect him from the blame and reproach which he casts upon himself. This is also the ground of repentance for a long past action at every recollection of it; a painful feeling produced by the moral sentiment, and which is practically void in so far as it cannot serve to undo what has been done.

Kant's reference to compromise and freedom in words only refers to Hume's compatibilism
(Hence Priestley, as a true and consistent fatalist, declares it absurd, and he deserves to be commended for this candour more than those who, while they maintain he mechanism of the will in fact, and its freedom in words only, yet wish it to be thought that they include it in their system of compromise, although they do not explain the possibility of such moral imputation.)

But the pain is quite legitimate, because when the law of our intelligible [supersensible] existence (the moral law) is in question, reason recognizes no distinction of time, and only asks whether the event belongs to me, as my act, and then always morally connects the same feeling with it, whether it has happened just now or long ago. For in reference to the supersensible consciousness of its existence (i. e., freedom) the life of sense is but a single phenomenon, which, inasmuch as it contains merely manifestations of the mental disposition with regard to the moral law (i. e., of the character), must be judged not according to the physical necessity that belongs to it as phenomenon, but according to the absolute spontaneity of freedom. It may therefore be admitted that, if it were possible to have so profound an insight into a man's mental character as shown by internal as well as external actions, as to know all its motives, even the smallest, and likewise all the external occasions that can influence them, we could calculate a man's conduct for the future with as great certainty as a lunar or solar eclipse; and nevertheless we may maintain that the man is free. In fact, if we were capable of a further glance, namely, an intellectual intuition of the same subject (which indeed is not granted to us, and instead of it we have only the rational concept), then we should perceive that this whole chain of appearances in regard to all that concerns the moral laws depends on the spontaneity of the subject as a thing in itself, of the determination of which no physical explanation can be given. In default of this intuition, the moral law assures us of this distinction between the relation of our actions as appearance to our sensible nature, and the relation of this sensible nature to the supersensible substratum in us. In this view, which is natural to our reason, though inexplicable, we can also justify some judgements which we passed with all conscientiousness, and which yet at first sight seem quite opposed to all equity. There are cases in which men, even with the same education which has been profitable to others, yet show such early depravity, and so continue to progress in it to years of manhood, that they are thought to be born villains, and their character altogether incapable of improvement; and nevertheless they are judged for what they do or leave undone, they are reproached for their faults as guilty; nay, they themselves (the children) regard these reproaches as well founded, exactly as if in spite of the hopeless natural quality of mind ascribed to them, they remained just as responsible as any other man. This could not happen if we did not suppose that whatever springs from a man's choice (as every action intentionally performed undoubtedly does) has as its foundation a free causality, which from early youth expresses its character in its manifestations (i. e., actions). These, on account of the uniformity of conduct, exhibit a natural connection, which however does not make the vicious quality of the will necessary, but on the contrary, is the consequence of the evil principles voluntarily adopted and unchangeable, which only make it so much the more culpable and deserving of punishment. There still remains a difficulty in the combination of freedom with the mechanism of nature in a being belonging to the world of sense; a difficulty which, even after all the foregoing is admitted, threatens freedom with complete destruction. But with this danger there is also a circumstance that offers hope of an issue still favourable to freedom; namely, that the same difficulty presses much more strongly (in fact as we shall presently see, presses only) on the system that holds the existence determinable in time and space to be the existence of things in themselves; it does not therefore oblige us to give up our capital supposition of the ideality of time as a mere form of sensible intuition, and consequently as a mere manner of representation which is proper to the subject as belonging to the world of sense; and therefore it only requires that this view be reconciled with this idea.

Hume also finds this difficulty of a causal chain an objection that he cannot deal with
The difficulty is as follows: Even if it is admitted that the supersensible subject can be free with respect to a given action, although, as a subject also belonging to the world of sense, he is under mechanical conditions with respect to the same action, still, as soon as we allow that God as universal first cause is also the cause of the existence of substance (a proposition which can never be given up without at the same time giving up the notion of God as the Being of all beings, and therewith giving up his all sufficiency, on which everything in theology depends), it seems as if we must admit that a man's actions have their determining principle in something which is wholly out of his power — namely, in the causality of a Supreme Being distinct from himself and on whom his own existence and the whole determination of his causality are absolutely dependent. In point of fact, if a man's actions as belonging to his modifications in time were not merely modifications of him as appearance, but as a thing itself, freedom could not be saved. Man would be a marionette or an automaton, like Vaucason's, prepared and wound up by the Supreme Artist. Self-consciousness would indeed make him a thinking automaton; but the consciousness of his own spontaneity would be mere delusion if this were mistaken for freedom, and it would deserve this name only in a comparative sense, since, although the proximate determining causes of its motion and a long series of their determining causes are internal, yet the last and highest is found in a foreign hand. Therefore I do not see how those who still insist on regarding time and space as attributes belonging to the existence of things in themselves can avoid admitting the fatality of actions; or if (like the otherwise acute Mendelssohn) they allow them to be conditions necessarily belonging to the existence of finite and derived beings, but not to that of the infinite Supreme Being, I do not see on what ground they can justify such a distinction, or, indeed, how they can avoid the contradiction that meets them, when they hold that existence in time is an attribute necessarily belonging to finite things in themselves, whereas God is the cause of this existence, but cannot be the cause of time (or space) itself (since this must be presupposed as a necessary a priori condition of the existence of things); and consequently as regards the existence of these things. His causality must be subject to conditions and even to the condition of time; and this would inevitably bring in everything contradictory to the notions of His infinity and independence. On the other hand, it is quite easy for us to draw the distinction between the attribute of the divine existence of being independent on all time-conditions, and that of a being of the world of sense, the distinction being that between the existence of being in itself and that of a thing in appearance. Hence, if this ideality of time and space is not adopted, nothing remains but Spinozism, in which space and time are essential attributes of the Supreme Being Himself, and the things dependent on Him (ourselves, therefore, included) are not substances, but merely accidents inhering in Him; since, if these things as His effects exist in time only, this being the condition of their existence in themselves, then the actions of these beings must be simply His actions which He performs in some place and time. Thus, Spinozism, in spite of the absurdity of its fundamental idea, argues more consistently than the creation theory can, when beings assumed to be substances, and beings in themselves existing in time, are regarded as effects of a Supreme Cause, and yet as not [belonging] to Him and His action, but as separate substances.

The above-mentioned difficulty is resolved briefly and clearly as follows: If existence in time is a mere sensible mode of representation belonging to thinking beings in the world and consequently does not apply to them as things in themselves, then the creation of these beings is a creation of things in themselves, since the notion of creation does not belong to the sensible form of representation of existence or to causality, but can only be referred to noumena. Consequently, when I say of beings in the world of sense that they are created, I so far regard them as noumena. As it would be a contradiction, therefore, to say that God is a creator of appearances, so also it is a contradiction to say that as creator He is the cause of actions in the world of sense, and therefore as appearances, although He is the cause of the existence of the acting beings (which are noumena). If now it is possible to affirm freedom in spite of the natural mechanism of actions as appearances (by regarding existence in time as something that belongs only to appearances, not to things in themselves), then the circumstance that the acting beings are creatures cannot make the slightest difference, since creation concerns their supersensible and not their sensible existence, and, therefore, cannot be regarded as the determining principle of the appearances.

Hume finds that this difficulty implicates a creator God in responsibility for evil
It would be quite different if the beings in the world as things in themselves existed in time, since in that case the creator of substance would be at the same time the author of the whole mechanism of this substance.

Of so great importance is the separation of time (as well as space) from the existence of things in themselves which was effected in the Critique of the Pure Speculative Reason.

It may be said that the solution here proposed involves great difficulty in itself and is scarcely susceptible of a lucid exposition. But is any other solution that has been attempted, or that may be attempted, easier and more intelligible? Rather might we say that the dogmatic teachers of metaphysics have shown more shrewdness than candour in keeping this difficult point out of sight as much as possible, in the hope that if they said nothing about it, probably no one would think of it. If science is to be advanced, all difficulties must be laid open, and we must even search for those that are hidden, for every difficulty calls forth a remedy, which cannot be discovered without science gaining either in extent or in exactness; and thus even obstacles become means of increasing the thoroughness of science. On the other hand, if the difficulties are intentionally concealed, or merely removed by palliatives, then sooner or later they burst out into incurable mischiefs, which bring science to ruin in an absolute scepticism.

Since it is, properly speaking, the notion of freedom alone amongst all the ideas of pure speculative reason that so greatly enlarges our knowledge in the sphere of the supersensible, though only of our practical knowledge, I ask myself why it exclusively possesses so great fertility, whereas the others only designate the vacant space for possible beings of the pure understanding, but are unable by any means to define the concept of them. I presently find that as I cannot think anything without a category, I must first look for a category for the rational idea of freedom with which I am now concerned; and this is the category of causality; and although freedom, a concept of the reason, being a transcendent concept, cannot have any intuition corresponding to it, yet the concept of the understanding — for the synthesis of which the former demands the unconditioned — (namely, the concept of causality) must have a sensible intuition given, by which first its objective reality is assured. Now, the categories are all divided into two classes — the mathematical, which concern the unity of synthesis in the conception of objects, and the dynamical, which refer to the unity of synthesis in the conception of the existence of objects. The former (those of magnitude and quality) always contain a synthesis of the homogeneous, and it is not possible to find in this the unconditioned antecedent to what is given in sensible intuition as conditioned in space and time, as this would itself have to belong to space and time, and therefore be again still conditioned. Whence it resulted in the Dialectic of Pure Theoretic Reason that the opposite methods of attaining the unconditioned and the totality of the conditions were both wrong. The categories of the second class (those of causality and of the necessity of a thing) did not require this homogeneity (of the conditioned and the condition in synthesis), since here what we have to explain is not how the intuition is compounded from a manifold in it, but only how the existence of the conditioned object corresponding to it is added to the existence of the condition (added, namely, in the understanding as connected therewith); and in that case it was allowable to suppose in the supersensible world the unconditioned antecedent to the altogether conditioned in the world of sense (both as regards the causal connection and the contingent existence of things themselves), although this unconditioned remained indeterminate, and to make the synthesis transcendent. Hence, it was found in the Dialectic of the Pure Speculative Reason that the two apparently opposite methods of obtaining for the conditioned the unconditioned were not really contradictory, e. g., in the synthesis of causality to conceive for the conditioned in the series of causes and effects of the sensible world, a causality which has no sensible condition, and that the same action which, as belonging to the world of sense, is always sensibly conditioned, that is, mechanically necessary, yet at the same time may be derived from a causality not sensibly conditioned — being the causality of the acting being as belonging to the supersensible world — and may consequently be conceived as free. Now, the only point in question was to change this may be into is; that is, that we should be able to show in an actual case, as it were by a fact, that certain actions imply such a causality (namely, the intellectual, sensibly unconditioned), whether they are actual or only commanded, that is, objectively necessary in a practical sense. We could not hope to find this connections in actions actually given in experience as events of the sensible world, since causality with freedom must always be sought outside the world of sense in the world of intelligence. But things of sense are the only things offered to our perception and observation. Hence, nothing remained but to find an incontestable objective principle of causality which excludes all sensible conditions: that is, a principle in which reason does not appeal further to something else as a determining ground of its causality, but contains this determining ground itself by means of that principle, and in which therefore it is itself as pure reason practical.

Just as Hume found the moral sentiments to be the grounds for natural beliefs such as causality, so Kant finds morality to be the grounding principle for freedom, which in his supersensible noumenal world breaks the causal chain of causality and necessity in the phenomenal world.
Now, this principle had not to be searched for or discovered; it had long been in the reason of all men, and incorporated in their nature, and is the principle of morality. Therefore, that unconditioned causality, with the faculty of it, namely, freedom, is no longer merely indefinitely and problematically thought (this speculative reason could prove to be feasible), but is even as regards the law of its causality definitely and assertorially known; and with it the fact that a being (I myself), belonging to the world of sense, belongs also to the supersensible world. this is also positively known, and thus the reality of the supersensible world is established and in practical respects definitely given, and this definiteness, which for theoretical purposes would be transcendent, is for practical purposes immanent. We could not, however, make a similar step as regards the second dynamical idea, namely, that of a necessary being. We could not rise to it from the sensible world without the aid of the first dynamical idea. For if we attempted to do so, we should have ventured to leave at a bound all that is given to us, and to leap to that of which nothing is given us that can help us to effect the connection of such a supersensible being with the world of sense (since the necessary being would have to be known as given outside ourselves). On the other hand, it is now obvious that this connection is quite possible in relation to our own subject, inasmuch as I know myself to be on the one side as an intelligible [supersensible] being determined by the moral law (by means of freedom), and on the other side as acting in the world of sense. It is the concept of freedom alone that enables us to find the unconditioned and intelligible for the conditioned and sensible without going out of ourselves. For it is our own reason that by means of the supreme and unconditional practical law knows that itself and the being that is conscious of this law (our own person) belong to the pure world of understanding, and moreover defines the manner in which, as such, it can be active. In this way it can be understood why in the whole faculty of reason it is the practical reason only that can help us to pass beyond the world of sense and give us knowledge of a supersensible order and connection, which, however, for this very reason cannot be extended further than is necessary for pure practical purposes.

Let me be permitted on this occasion to make one more remark, namely, that every step that we make with pure reason, even in the practical sphere where no attention is paid to subtle speculation, nevertheless accords with all the material points of the Critique of the Theoretical Reason as closely and directly as if each step had been thought out with deliberate purpose to establish this confirmation. Such a thorough agreement, wholly unsought for and quite obvious (as anyone can convince himself, if he will only carry moral inquiries up to their principles), between the most important proposition of practical reason and the often seemingly too subtle and needless remarks of the Critique of the Speculative Reason, occasions surprise and astonishment, and confirms the maxim already recognized and praised by others, namely, that in every scientific inquiry we should pursue our way steadily with all possible exactness and frankness, without caring for any objections that may be raised from outside its sphere, but, as far as we can, to carry out our inquiry truthfully and completely by itself. Frequent observation has convinced me that, when such researches are concluded, that which in one part of them appeared to me very questionable, considered in relation to other extraneous doctrines, when I left this doubtfulness out of sight for a time and only attended to the business in hand until it was completed, at last was unexpectedly found to agree perfectly with what had been discovered separately without the least regard to those doctrines, and without any partiality or prejudice for them. Authors would save themselves many errors and much labour lost (because spent on a delusion) if they could only resolve to go to work with more frankness.

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