Critique of Pure Reason

It is different with the transcendental division of a phenomenon. How far that may extend is not a matter of experience, but a principle of reason, which never allows us to consider the empirical regressus in the decomposition of extended bodies, according to the nature of these phenomena, as at any time absolutely completed.

For if phenomena are things by themselves, freedom cannot be saved. Nature in that case is the complete and sufficient cause determining every event, and its condition is always contained in that series of phenomena only which, together with their effect, are necessary under the law of nature.

A great part, perhaps the greatest part, of the business of our reason consists in the analysation of the conceptions which we already possess of objects.

Unavoidable contradictions, we must not rest satisfied with the mere natural disposition of the mind to metaphysics, that is, with the existence of the faculty of pure reason, whence, indeed, some sort of metaphysical system always arises;

Dogmatism is thus the dogmatic procedure of pure reason without previous criticism of its own powers, and in opposing this procedure, we must not be supposed to lend any countenance to that loquacious shallowness which arrogates to itself the name of popularity, nor

The sacredness of religion, and the authority of legislation, are by many regarded as grounds of exemption from the examination of this tribunal. But, if they on they are exempted, they become the subjects of just suspicion, and cannot lay claim to sincere respect, which reason accords only to that which has stood the test of a free and public examination.

The greatest and perhaps only utility of all philosophy of pure reason is thus only negative, namely that it does not serve for expansion, as an organon, but rather, as a discipline, serves for the determination of boundaries, and instead of discovering truth it has only the silent merit of guarding against errors.

It falls into this difficulty without any fault of its own. It begins with principles, which cannot be dispensed with in the field of experience, and the truth and sufficiency of which are, at the same time, insured by experience. With these principles it rises, in obedience to the laws of its own nature, to ever higher and more remote conditions. But it quickly discovers that, in this way, its labours must remain ever incomplete, because new questions never cease to present themselves; and thus it finds itself compelled to have recourse to principles which transcend the region of experience, while they are regarded by common sense without distrust. It thus falls into confusion and contradictions, from which it conjectures the presence of latent errors, which, however, it is unable to discover, because the principles it employs, transcending the limits of experience, cannot be tested by that criterion. The arena of these endless contests is called Metaphysic.

The march of mathematics is pursued on a broad and magnificent highway, which the latest posterity shall frequent without fear of danger or impediment.

...Reason should take on anew the most difficult of all its tasks, namely, that of self-knowledge, and to institute a court of justice, by which reason may secure its rightful claims while dismissing all its groundless pretensions, and this not by mere decrees but according to its own eternal and unchangeable laws; and this court is none other than the critique of pure reason itself.

Enlightenment is man's emergence from his self-imposed immaturity. Nothing is required for this enlightenment except freedom; and the freedom in question is the least harmful of all, namely, the freedom to use with and publicly in all matters.

Our reason has this peculiar fate that, with reference to one class of its knowledge, it is always troubled with questions which cannot be ignored, because they spring from the very nature of reason, and which cannot be answered, because they transcend the powers of human reason.

Space is only the form of external intuition, and not a real object that could be perceived externally, nor is it a correlate of phenomena, but the form of phenomena themselves. Space, therefore, cannot exist absolutely (by itself) as something determining the existence of things, because it is no object, but only the form of possible objects. Things, therefore, as phenomenal, may indeed determine space, that is, impart reality to one or other of its predicates (quality and relation); but space, on the other side, as something existing by itself, cannot determine the reality of things in regard to quantity or form, because it is nothing real in itself.

How things may be in themselves, without regard to the representations through which they affect us, is utterly beyond the sphere of our cognition.

And intestine wars introduced the reign of anarchy; while the sceptics, like nomadic tribes, who hate a permanent habitation and settled mode of living, attacked from time to time those who had organized themselves into civil communities.

I have therefore found it necessary to deny knowledge, in order to make room for faith.

To think an object, then, is not the same as to know an object.

I have no knowledge of myself as I am but only as I appear to myself. The consciousness of oneself is therefore very far from being a knowledge of oneself.

Such is the genesis of these general convictions of mankind, so far as they depend on rational grounds; and this public property not only remains undisturbed, but is even raised to greater importance, by the doctrine that the schools have no right to arrogate to themselves a more profound insight into a matter of general human concernment than that to which the great mass of men, ever held by us in the highest estimation, can without difficulty attain, and that the schools should, therefore, confine themselves to the elaboration of these universally comprehensible and, from a moral point of view, amply satisfactory proofs.

[...] probability is a truth, known however through insufficient grounds, the knowledge of which is therefore deficient, but not deceptive [...]

It would be impossible to represent to ourselves darkness, unless light had been given to the senses.

To the cosmological question, therefore, respecting the quantity of the world, the first and negative answer is, that the world has no first beginning in time, and no extreme limit in space.

We now concern ourselves with a labor less spectacular but nevertheless not unrewarding: that of making the terrain for these majestic moral edifices level and firm enough to be built upon; for under this ground there are all sorts of passageways, such as moles might have dug, left over from reason's vain but confident treasure hunting, that make every building insecure.

Our knowledge springs from two fundamental sources of our mind; the first is to receive representations (receptivity of impressions), the second is the faculty of knowing an object through these representations (spontaneity of concepts). Through the first an object is *given* to us, through the second the object is *thought* in relation to that representation (which is a mere determination of the mind). Intuition and concepts constitute, therefore, the elements of all our knowledge, so that neither concepts without an intuition in some way corresponding to them, nor intuition without concepts can yield knowledge. Both are either pure or empirical. They are empirical when they contain sensation (sensation presupposes the actual presence of the object). They are *pure* when no sensation is mixed in with the representation. Sensation may be called the matter of sensible knowledge. Pure intuition, therefore, contains only the form under which something is intuited, and the pure concepts contains only the form of thinking an object in general. Pure intuitions and pure concepts alone are possible *a priori*, empirical intuitions and empirical concepts only *a posteriori*. We call *sensibility* the *receptivity* of our mind to receive representations insofar as it is in some wise affected, while the *understanding*, on the other hand, is our faculty of producing representations by ourselves, or the *spontaneity* of knowledge. We are so constituted that our intuition can never be other than *sensible*; that is, it contains only the mode in which we are affected by objects. The faculty, on the contrary, which enables us to *think* the object of sensible intuition is the *understanding*. Neither of these properties is to be preferred to the other. Without sensibility no object would be given to us, without understanding no object would be thought. Thoughts without content are empty, intuitions without concepts are blind. It is, therefore, just as necessary to make our concepts sensible (i.e., to add the object to them in intuition) as to make our intuitions understandable (i.e., to bring them under concepts). These two faculties or capacities cannot exchange their functions. The understanding cannot intuit anything, the senses cannot think anything. Only from their union can knowledge arise. But this is no reason for confounding their respective contributions; rather, it gives us a strong reason for carefully separating and distinguishing the one from the other. We therefore distinguish the science of the rules of sensibility in general, i.e., aesthetic, from the science of the rules of the understanding in general, i.e., logic.

That there may be inhabitants in the moon, although no one has ever observed them, must certainly be admitted; but this assertion means only, that we may in the possible progress of experience discover them at some future time.

It will be seen how there can be the idea of a special science, the *critique of pure reason* as it may be called. For reason is the faculty which supplies the *principles* of *a priori* knowledge. Pure reason therefore is that which contains the principles of knowing something entirely *a priori*. An *organon* of pure reason would be the sum total of the principles by which all pure *a priori* knowledge can be acquired and actually established. Exhaustive application of such an organon would give us a system of pure reason. But as this would be a difficult task, and as at present it is still doubtful whether indeed an expansion of our knowledge is possible here at all, we may regard a science that merely judges pure reason, its sources and limits, as the *propaedeutic* to the system of pure reason. In general, it would have to be called only a *critique*, not a *doctrine* of pure reason. Its utility, in regard to speculation, would only be negative, for it would serve only to purge rather than to expand our reason, and, which after all is a considerable gain, would guard reason against errors. I call all knowledge *transcendental* which deals not so much with objects as with our manner of knowing objects insofar as this manner is to be possible *a priori*. A system of such concepts would be called *transcendental philosophy*. But this is still, as a beginning, too great an undertaking. For since such a science must contain completely both analytic and synthetic *a priori* knowledge, it is, as far as our present purpose is concerned, much too comprehensive. We will be satisfied to carry the analysis only so far as is indispensably necessary in order to understand in their whole range the principles of *a priori* synthesis, with which alone we are concerned. This investigation, which properly speaking should be called only a transcendental critique but not a doctrine, is all we are dealing with at present. It is not meant to expand our knowledge but only to correct it, and to become the touchstone of the value, or lack of value, of all *a priori* knowledge. Such a critique is therefore the preparation, as far as possible, for a new organon, or, if this should turn out not to be possible, for a canon at least, according to which, thereafter, the complete system of a philosophy of pure reason, whether it serve as an expansion or merely as a limitation of its knowledge, may be carried out both analytically and synthetically. That such a system is possible, indeed that it need not be so comprehensive as to cut us off from the hope of completing it, may already be gathered from the fact that it would have to deal not with the nature of things, which is inexhaustible, but with the understanding which makes judgments about the nature of things, and with this understanding again only as far as its *a priori* knowledge is concerned. The supply of this *a priori* knowledge cannot be hidden from us, as we need not look for it outside the understanding, and we may suppose this supply to prove sufficiently small for us to record completely, judge as to its value or lack of value and appraise correctly. Still less ought we to expect here a critique of books and systems of pure reason, but only the critique of the faculty of pure reason itself. Only once we are in possession of this critique do we have a reliable touchstone for estimating the philosophical value of old and new works on this subject. Otherwise, an unqualified historian and judge does nothing but pass judgments upon the groundless assertions of others by means of his own, which are equally groundless.

...whose true object is to shed the clearest light on every step which reason takes.

For if we regard space and time as properties that must, as regards their possibility, be found in things in themselves, [...] then we really cannot blame the good Bishop Berkeley for degrading bodies to mere illusion. Nay, even our own existence, which would thus be made dependent on the self-subsistent reality of a non-entity such as time, would, along with this time, be changed into mere illusion - an absurdity of which hitherto no one has been guilty.

The usual touchstone of whether what someone asserts is mere persuasion or at least a subjective conviction, i.e., firm belief, is betting. Often someone pronounces his propositions with such confident and inflexible defiance that he seems to have entirely laid aside all concern for error. A bet disconcerts him. Sometimes he reveals that he is persuaded enough for one ducat but not for ten. For he would happily bet one, but at ten he suddenly becomes aware of what he had not previously noticed, namely that it is quite possible that he has erred.

We see that the ens rationis is distinguished from the nihil negativum or pure nothing by the consideration that the former must not be reckoned among possibilities, because it is a mere fiction- though not self-contradictory, while the latter is completely opposed to all possibility, inasmuch as the conception annihilates itself. Both, however, are empty conceptions. On the other hand, the nihil privativum and ens imaginarium are empty data for conceptions. If light be not given to the senses, we cannot represent to ourselves darkness, and if extended objects are not perceived, we cannot represent space. Neither the negation, nor the mere form of intuition can, without something real, be an object.