Immanuel Kant

Falsehood, ingratitude, injustice, the puerility of the ends which we ourselves look upon as great and momentous… these all so contradict the idea of what men might be if they only would, and are so at variance with our active wish to see them better, that, to avoid hating where one cannot love, it seems but a slight sacrifice to forego all the joys of fellowship with our kind.

On the other hand, the moral law, although it gives no such prospect, does provide a fact absolutely inexplicable from any data of the world of sense or from the whole compass of the theoretical use of reason, and this fact points to a pure intelligible world―indeed, it defines it positively and enable us to know something of it, namely a law. This law gives to the sensible world, as sensuous nature (as this concerns rational beings), the form of an intelligible world, i.e., the form of supersensuous nature, without interfering with the mechanism of the former. Nature, in the widest sense of the word, is the existence of things under laws. The sensuous nature of rational beings in general is their existence under empirically conditioned laws, and therefore it is, from the point of view of reason, heteronomy. The supersensuous nature of the same beings, on the other hand, is their existence according to laws which are independent of all empirical conditions and which therefore belong to the autonomy of pure reason. And since the laws, according to which the existence of things depends on cognition, are practical, supersensuous nature, so far as we can form a concept of it, is nothing else than nature under the autonomy of the pure practical reason. The law of this autonomy is the moral law, and it, therefore, is the fundamental law of supersensuous nature and of a pure world of the understanding, whose counterpart must exist in the world of sense without interfering with the laws of the latter. The former could be called the archetypal world (*natura archetypa*) which we know only by reason; the latter, on the other hand, could be called the ectypal world (*natura ectypa*), because it contains the possible effect of the idea of the former as the determining ground of the will.

By this freedom the will of a rational being, as belonging to the sensuous world, recognizes itself to be, like all other efficient causes, necessarily subject to the laws of causality, while in practical matters, in its other aspect as a being in itself, it is conscious of its existence as determinable in an intelligible order of things. It is conscious of this not by virtue of a particular intuition of itself but because of certain dynamic laws which determine its causality in the world of sense, for it has been sufficiently proved in another place that if freedom is attributed to us, it transfers us into an intelligible order of things.

Our critique is not opposed to the *dogmatic procedure* of reason in its pure knowledge as science (for science must always be dogmatic, that is, derive its proof from secure *a priori* principles), but only to *dogmatism*, that is, to the presumption that it is possible to make any progress with pure (philosophical) knowledge from concepts according to principles, such as reason has long been in the habit of using, without first inquiring in what way, and by what right, it has come to posses them. Dogmatism is therefore the dogmatic procedure of pure reason, *without a preceding critique of its own powers*; and our opposition to this is not intended to defend that loquacious shallowness which arrogates to itself the name of popularity, much less that skepticism which makes short work of the whole of metaphysics. On the contrary, our critique is meant to form a necessary preparation in support of metaphysics as a thorough science, which must necessarily be carried out dogmatically and strictly systematically, so as to satisfy all the demands, no so much of the public at large, as of the Schools. This is an indispensable demand for it has undertaken to carry out its work entirely *a priori*, and thus to carry it out to the complete satisfaction of speculative reason. In the execution of this plan, as traced out by the critique, that is, in a future system of metaphysics, we shall have to follow the strict method of the celebrated Wolff, the greatest of all dogmatic philosophers. He was the first to give an example (and by his example initiated, in Germany, that spirit of thoroughness which is not yet extinct) of how the secure course of a science could be attained only through the lawful establishment of principles, the clear determination of concepts, the attempt at strictness of proof and avoidance of taking bold leaps in our inferences. He was therefore most eminently qualified to give metaphysics the dignity of a science, if it had only occurred to him to prepare his field in advance by criticism of the organ, that is, of pure reason itself―an omission due not so much to himself as to the dogmatic mentality of his age, about which the philosophers of his own, as well as of all previous times, have no right to reproach one another. Those who reject both the method of Wolff and the procedure of the critique of pure reason can have no other aim but to shake off the fetters of *science* altogether, and thus to change work into play, certainty into opinion and philosophy into philodoxy.

The purpose of this critique of pure speculative reason consists in the attempt to change the old procedure of metaphysics, and to bring about a complete revolution after the example set by geometers and investigators of nature. This critique is a treatise on the method, not a system of the science itself; but nevertheless it marks out the whole plan of this science, both with regard to its limits and with regard to its inner organization. For it is peculiar to pure speculative reason that it is able, indeed bound, to measure its own powers according to the different ways in which it chooses its objects for thought, and to enumerate exhaustively the different ways of choosing its problems, thus tracing a complete outline of a system of metaphysics. This is due to the fact that, with regard to the first point, nothing can be attributed to objects in *a priori* knowledge, except what the thinking subject takes from within itself; while, with regard to the second point, pure reason, as far as its principles of knowledge are concerned, forms a separate and independent unity, in which, as in an organized body, every member exists for the sake of all the others, and all the others exist for the sake of the one, so that no principle can be safely applied in *one* relation unless it has been carefully examined in *all* its relations to the whole use of pure reason. Hence, too, metaphysics has this singular advantage, an advantage which cannot be shared by any other rational science which has to deal with objects (for *logic* deals only with the form of thought in general), that if by means of this critique it has been set upon the secure course of a science, it can exhaustively grasp the entire field of knowledge pertaining to it, and can thus finish its work and leave it to posterity as a capital that can never be added to, because it has to deal only with principles and with the limitations of their use, as determined by these principles themselves. And this completeness becomes indeed an obligation if metaphysics is to be a fundamental science, of which we must be able to say, *nil actum reputants, si quid superesset agendum* [to think that nothing was done for as long as something remained to be done].

This experiment succeeds as hoped and promises to metaphysics, in its first part, which deals with those *a priori* concepts to which the corresponding objects may be given in experience, the secure course of a science. For by thus changing our point of view, the possibility of *a priori* knowledge can well be explained, and, what is still more, the laws which *a priori* lie at the foundation of nature, as the sum total of the objects of experience, may be supplied with satisfactory proofs, neither of which was possible within the procedure hitherto adopted. But there arises from this deduction of our faculty of knowing *a priori*, as given in the first part of metaphysics, a somewhat startling result, apparently most detrimental to that purpose of metaphysics which has to be treated in its second part, namely the impossibly of using this faculty to transcend the limits of possible experience, which is precisely the most essential concern of the science of metaphysics. But here we have exactly the experiment which, by disproving the opposite, establishes the truth of the first estimate of our *a priori* rational knowledge, namely, that it is directed only at appearances and must leave the thing in itself as real for itself but unknown to us. For that which necessarily impels us to to go beyond the limits of experience and of all appearances is the *unconditioned*, which reason rightfully and necessarily demands, aside from everything conditioned, in all things in themselves, so that the series of conditions be completed. If, then, we find that, under the supposition that our empirical knowledge conforms to objects as things in themselves, the unconditioned *cannot be thought without contradiction*, while under the supposition that our representation of things as they are given to us does not conform to them as things in themselves, but, on the contrary, that these objects as appearance conform to our mode of representation, then *the contradiction vanishes*; and if we find, therefore, that the unconditioned cannot be encountered in things insofar as we are acquainted with them (insofar as they are given to us), but only in things insofar as we are not acquainted with them, that is, insofar as they are things in themselves; then it becomes apparent that what we at first assumed only for the sake of experiment is well founded. However, with speculative reason unable to make progress in the field of the supersensible, it is still open to us to investigate whether in reason's practical knowledge data may not be found which would enable us to determine that transcendent rational concept of the unconditioned, so as to allow us, in accordance with the wish of metaphysics, to get beyond the limits of all possible experience with our *a priori* knowledge, which is possible in practical matters only. Within such a procedure, speculative reason has always at least created a space for such an expansion, even if it has to leave it empty; none the less we are at liberty, indeed we are summoned, to fill it, if we are able to do so, with practical *data* of reason.

It is true, no doubt, that this principle of the necessary unity of apperception is itself an identical and therefore an analytic proposition; but it shows, nevertheless, the necessity of a synthesis of the manifold given in an intuition, a synthesis without which it would be impossible to think the thoroughgoing identity of self-consciousness. For through the *I*, as a simple representation, nothing manifold is given; only in intuition, which is distinct from this representation, can a manifold be given, and then, through *combination*, be thought in one consciousness. An understanding in which through self-consciousness all the manifold would be given at the same time would be one that *intuits*; our understanding can do nothing but *think*, and must seek intuition in the senses. I am conscious, therefore, of the identical self with respect to the manifold of the representations that are given to me in an intuition, because I call them one and all *my* representations, as constituting *one* intuition. This means that I am conscious *a priori* of a necessary synthesis of them, which is called the original synthetic unity of apperception, and under which all representations given to me must stand, but under which they must also be brought by means of a synthesis.

Conscience is an instinct to pass judgment upon ourselves in accordance with moral laws.

A similar experiment may be tried in metaphysics as regards the *intuition* of objects. If the intuition had to conform to the constitution of objects, I would not understand how we could know anything of them *a priori*; but if the object (as object of the senses) conformed to the constitution of our faculty of intuition, I could very well conceive such a possibility. As, however, I cannot rest in these intuitions if they are to become knowledge, but have to refer them as representations, to something as their object, and must determine this object through them, I can assume either that the *concepts* through which I arrive at this determination also conform to the object, and I would again be as perplexed about how I can know anything about it *a priori*; or else that the objects, or what is the same thing, the *experience* in which alone they are known (as objects that are given to us), conform to those concepts. In the latter case, I recognize an easier solution because experience itself is a kind of knowledge that requires understanding; and this understanding has its rules which I must presuppose as existing within me even before objects are given to me, and hence *a priori*. These rules are expressed in *a priori* concepts to which all objects of experience must necessarily conform, and with which they must agree. With regard to objects, insofar as they are thought merely through reason and thought indeed as necessary, and which can never, at least not in the way in which reason thinks them, be given in experience, the attempts at thinking them (for they must admit of being thought) will subsequently furnish an excellent touchstone of what we are adopting as our new method of thought, namely, that we know of things *a priori* only that which we ourselves put into them.

Metaphysics, a completely isolated and speculative branch of rational knowledge which is raised above all teachings of experience and rests on concepts only (not, like mathematics, on their application to intuition), in which reason therefore is meant to be its own pupil, has hitherto not had the good fortune to enter upon the secure path of a science, although it is older than all other sciences, and would survive even if all the rest were swallowed up in the abyss of an all-destroying barbarism. Reason in metaphysics, even if it tries, as it professes, only to gain *a priori* insight into those laws which are confirmed by our most common experience, is constantly being brought to a standstill, and we are obliged again and again to retrace our steps, as they do not lead us where we want to go. As to unanimity among its participants, there is so little of it in metaphysics that it has rather become an arena that would seem especially suited for those who wish to exercise themselves in mock fights, where no combatant has as yet succeeded in gaining even an inch of ground that he could call his permanent possession. There cannot be any doubt, therefore, that the method of metaphysics has hitherto consisted in a mere random groping, and, what is worst of all, in groping among mere concepts. What, then, is the reason that this secure scientific course has not yet been found? Is this, perhaps, impossible? Why, in that case, should nature have afflicted our reason with the restless aspiration to look for it, and have made it one of its most important concerns? What is more, how little should we be justified in trusting our reason, with regard to one of the most important objects of which we desire knowledge, it not only abandons us, but lures us on by delusions, and in the end betrays us! Or, if hitherto we have only failed to meet with the right path, what indications are there to make us hope that, should we renew our search, we shall be more successful than others before us?

It must be *possible* for the *I think* to accompany all my representations: for otherwise something would be represented within me that could not be thought at all, in other words, the representation would either be impossible, or at least would be nothing to me. That representation which can be given prior to all thought is called *intuition*, and all the manifold of intuition has, therefore, a necessary relation to the *I think* in the same subject in which this manifold of intuition is found. This representation (the *I think*), however, is an act of *spontaneity*, that is, it cannot be considered as belonging to sensibility. I call it *pure apperception*, in order to distinguish it from empirical apperception, as also from original apperception, because it is that self-consciousness which, by producing the representations, *I think* (which must be capable of accompanying all other representations, and which is one and the same in all consciousness), cannot itself be accompanied by any further representations. I also call the unity of apperception the *transcendental* unity of self-consciousness, in order to indicate that *a priori* knowledge can be obtained from it. For the manifold representations given in an intuition would not one and all be *my* representations, if they did not all belong to one self-consciousness. What I mean is that, as my representations (even though I am not conscious of them as that), they must conform to the condition under which alone they *can* stand together in one universal self-consciousness, because otherwise they would not one and all belong to me. From this original combination much can be inferred. The thoroughgoing identity of the apperception of a manifold that is given in intuition contains a synthesis of representations, and is possible only through the consciousness of this synthesis. For the empirical consciousness which accompanies different representations is itself dispersed and without reference to the identity of the subject. Such a reference comes about, not simply through my accompanying every representation with consciousness, but through my *adding* one representation to another and being conscious of the synthesis of them. Only because I am able to combine a manifold of given representations *in one consciousness* is it possible for me to represent to myself the *identity of the consciousness in these representations*, that is, only under the presupposition of some *synthetic* unity of apperception is the *analytic* unity of apperception possible. The thought that the representations given in intuition belong one and all *to me*, is therefore the same as the thought that I unite them in one self-consciousness, or can at least do so; and although that thought itself is not yet the consciousness of the synthesis of representations, it nevertheless presupposes the possibility of this synthesis. In other words, it is only because I am able to comprehend the manifold of representations in one consciousness that I call them one and all *my* representations. For otherwise I should have as many-coloured and varied a self as I have representations of which I am conscious. Synthetic unity of the manifold of intuitions, as given *a priori*, is thus the ground of the identity of apperception itself, which precedes *a priori* all *my* determinate thought. Combination, however, does not lie in the objects, and cannot be borrowed from them by perception and thus first be taken into the understanding. It is, rather, solely an act of the understanding, which itself is nothing but the faculty of combining *a priori* and of bringing the manifold of given representations under the unity of apperception; and the principle of this unity is, in fact, the supreme principle of all human knowledge.

Metaphysics is a dark ocean without shores or a lighthouse.

Man's greatest concern is to know how he shall properly fill his place in the universe and correctly understand what he must be in order to be a man.

Any change makes me apprehensive, even if it offers the greatest promise of improving my condition, and I am persuaded by this natural instinct of mine that I must take heed if I wish that the threads which the Fates spin so thin and weak in my case to be spun to any length. My great thanks, to my well-wishers and friends, who think so kindly of me as to undertake my welfare, but at the same time a most humble request to protect me in my current condition from any disturbance.

We are enriched by not what we posses, but by what we can do without.

From such crooked timber as humankind is made of nothing entirely straight can be made.

Freedom is alone the unoriginated birthright of man, and belongs to him by force of his humanity; and is independent of the will and co-action of every other…

If there is any science man really needs it is the one I teach, of how to occupy properly that place in creation that is assigned to man, and how to learn from it what one must be in order to be a man.

Things which we see are not by themselves what we see.

A learned woman might just as well have a beard, for that expresses in a more recognizable form the profundity for which she strives.

The character of the species, as it is indicated by the experience of all ages and all peoples, is this: that taken collectively (the human race as one whole), it is a multitude of persons, existing successively and side by side, who cannot do without associating peacefully and yet cannot avoid constantly offending one another.

Chisels and hammers may suffice to work a piece of wood, but for etching we require an etcher's needle. Thus common sense and speculative understanding are both useful, but each in its own way: the former in judgments which apply immediately to experience; the latter when we judge universally from mere concepts, as in metaphysics, where sound common sense, so called in spite of the inappropriateness of the word, has no right to judge at all.

Nothing happens by blind chance.

Science can be divided into an infinite number of disciplines, and the amount of knowledge that can be pursued in each discipline is limitless. The most critical piece of knowledge, then, is the knowledge of what is essential to learn and what isn’t. A huge amount of knowledge is accumulated at present. Soon our abilities will be too weak, and our lives too short, to study this knowledge. We have vast treasures of knowledge at our disposal but after we study them, we often do not use them at all. It would be better not to have this burden, this unnecessary knowledge, which we do not really need.

The real is not given to us, but put to us by way of a riddle.

Philosophy cannot be taught; only philosophizing can be learned.

A person born blind cannot frame the smallest conception of darkness, because he has none of light. The savage knows nothing of poverty, because he does not know wealth and the ignorant has no conception of his ignorance, because he has none of knowledge.

A man shouldn’t claim to know even himself as he really is by knowing himself through inner sensation—i.e. by introspection. For since he doesn’t produce himself (so to speak) or get his concept of himself a priori but only empirically, it is natural that he gets his knowledge of himself through inner sense and consequently only through how his nature appears and how his consciousness is affected. But beyond the character of his own subject, which is made up out of these mere appearances, he necessarily assumes something else underlying it, namely his I as it is in itself. Thus in respect to mere perception and receptivity to sensations he must count himself as belonging to the sensible world; but in respect to whatever pure activity there may be in himself (which reaches his consciousness directly and not by affecting the inner or outer senses) he must count himself as belonging to the intellectual world—though he doesn’t know anything more about it.

Out of timber so crooked as that from which man is made nothing entirely straight can be carved .

Even philosophers will praise war as ennobling mankind, forgetting the Greek who said: 'War is bad in that it begets more evil than it kills.