“THERE can be no doubt that all our knowledge begins with experience. For how should our faculty of knowledge be awakened into action did not objects affecting our senses partly of themselves produce representations, partly arouse the activity of our understanding to compare these representations, and, by combining or separating them, work up the raw material of the sensible impressions into that knowledge of objects which is entitled experience?”
“In the order of time, therefore, we have no knowledge antecedent to experience, and with experience all our knowledge begins.”
“This, then, is a question which at least calls for closer examination, and does not allow of any off-hand answer: – whether there is any knowledge that is thus independent of experience and even of all impressions of the senses. Such knowledge is entitled a priori, and distinguished from the empirical, which has its sources a posteriori, that is, in experience.”
“it has been customary to say, even of much knowledge that is derived from empirical sources, that we have it or are capable of having it a priori, meaning thereby that we do not derive it immediately from experience, but from a universal rule – a rule which is itself, however, borrowed by us from experience.”
“Thus we would say of a man who undermined the foundations of his house, that he might have known a priori that it would fall, that is, that he need not have waited for the experience of its actual falling. But still he could not know this completely a priori. For he had first to learn through experience that bodies are heavy, and therefore fall when their supports are withdrawn.”
“In what follows, therefore, we shall understand by a priori knowledge, not knowledge independent of this or that experience, but knowledge absolutely independent of all experience.”
“Opposed to it is empirical knowledge, which is knowledge possible only a posteriori, that is, through experience.”
“A - priori modes of knowledge are entitled pure when there is no admixture of anything empirical. Thus, for instance, the proposition, ‘every alteration has its cause’, while an a priori proposition, is not a pure proposition, because alteration is a concept which can be derived only from experience.”
“First, then, if we have a proposition which in being thought is thought as necessary, it is an a priori judgment; and if, besides, it is not derived from any proposition except one which also has the validity of a necessary judgment, it is an absolutely a priori judgment.”
“Secondly, experience never confers on its judgments true or strict but only assumed and comparative universality, through induction.”
“For whence could experience derive its certainty, if all the rules, according to which it proceeds, were always themselves empirical, and therefore contingent?”
“Such rules could hardly be regarded as first principles.”
“Such a priori origin is manifest in certain concepts, no less than in judgments. If we remove from our empirical concept of a body, one by one, every feature in it which is [merely] empirical, the colour, the hardness or softness, the weight, even the impenetrability, there still remains the space which the body (now entirely vanished) occupied, and this cannot be removed.”
“Philosophy stands in Need of a Science which shall Determine the Possibility, the Principles, and the Extent of All A Priori Knowledge”
“But what is still more extraordinary than all the preceding is this, that certain modes of knowledge leave the field of all possible experiences and have the appearance of extending the scope of our judgments beyond all limits of experience, and this by means of concepts to which no corresponding object can ever be given in experience.”
“These unavoidable problems set by pure reason itself are God, freedom, and immortality.”
“The science which, with all its preparations, is in its final intention directed solely to their solution is metaphysics; and its procedure is at first dogmatic, that is, it confidently sets itself to this task without any previous examination of the capacity or incapacity of reason for so great an undertaking.”
“Now it does indeed seem natural that, as soon as we have left the ground of experience, we should, through careful enquiries, assure ourselves as to the foundations of any building that we propose to erect, not making use of any knowledge that we possess without first determining whence it has come, and not trusting to principles without knowing their origin.”
“Besides, once we are outside the circle of experience, we can be sure of not being contradicted by experience.”
“The charm of extending our knowledge is so great that nothing short of encountering a direct contradiction can suffice to arrest us in our course; and this can be avoided, if we are careful in our fabrications – which none the less will still remain fabrications.”
“Mathematics gives us a shining example of how far, independently of experience, we can progress in a priori knowledge. It does, indeed, occupy itself with objects and with knowledge solely in so far as they allow of being exhibited in intuition. But this circumstance is easily overlooked, since the intuition, in being thought, can itself be given a priori, and is therefore hardly to be distinguished from a bare and pure concept.”
“It is, indeed, the common fate of human reason to complete its speculative structures as speedily as may be, and only afterwards to enquire whether the foundations are reliable.”
“a great, perhaps the greatest, part of the business of our reason consists in analysis of the concepts which we already have of objects.”
“This analysis supplies us with a considerable body of knowledge, which, while nothing but explanation or elucidation of what has already been thought in our concepts, though in a confused manner, is yet prized as being, at least as regards its form, new insight.”
“But so far as the matter or content is concerned, there has been no extension of our previously possessed concepts, but only an analysis of them. Since this procedure yields real knowledge a priori, which progresses in an assured and useful fashion, reason is so far misled as surreptitiously to introduce, without itself being aware of so doing, assertions of an entirely different order, in which it attaches to given concepts others completely foreign to them, and moreover attaches them a priori. And yet it is not known how reason can be in position to do this. Such a question is never so much as thought of. I shall therefore at once proceed to deal with the difference between these two kinds of knowledge.”
“IV. The Distinction between Analytic and Synthetic Judgments”
“In all judgments in which the relation of a subject to the predicate is thought (I take into consideration affirmative judgments only, the subsequent application to negative judgments being easily made), this relation is possible in two different ways. Either the predicate to the subject A, as something which is (covertly) contained in this concept A; or outside the concept A, although it does indeed stand in connection with it. In the one case I entitle the judgment analytic, in the other synthetic.”
“Analytic judgments (affirmative) are therefore those in which the connection of the predicate with the subject is thought through identity; those in which this connection is thought without identity should be entitled synthetic.”
“If I say, for instance, ‘All bodies are extended’, this is an analytic judgment. For I do not require to go beyond the concept which I connect with ‘body’ in order to find extension as bound up with it. To meet with this predicate, I have merely to analyse the concept, that is, to become conscious to myself of the manifold which I always think in that concept. The judgment is therefore analytic.”
“But when I say, ‘All bodies are heavy’, the predicate is something quite different from anything that I think in the mere concept of body in general; and the addition of such a predicate therefore yields a synthetic judgment.”
“Judgments of experience, as such, are one and all synthetic. For it would be absurd to found an analytic judgment on experience. Since, in framing the judgment, I must not go outside my concept, there is no need to appeal to the testimony of experience in its support.”
“That a body is extended is a proposition that holds a priori and is not empirical. For, before appealing to experience, I have already in the concept of body all the conditions required for my judgment. I have only to extract from it, in accordance with the principle of contradiction, the required predicate, and in so doing can at the same time become conscious of the necessity of the judgment – and that is what experience could never have taught me.”
“On the other hand, though I do not include in the concept of a body in general the predicate ‘weight’, none the less this concept indicates an object of experience through one of its parts, and I can add to that part other parts of this same experience, as in this way belonging together with the concept. From the start I can apprehend the concept of body analytically through the characters of extension, impenetrability, figure, etc. , all of which are thought in the concept. Now, however, looking back on the experience from which I have derived this concept of body, and finding weight to be invariably connected with the above characters, I attach it as a predicate to the concept; and in doing so I attach it synthetically, and am therefore extending my knowledge.”
“The possibility of the synthesis of the predicate ‘weight’ with the concept of ‘body’ thus rests upon experience.”
“While the one concept is not contained in the other, they yet belong to one another, though only contingently, as parts of a whole, namely, of an experience which is itself a synthetic combination of intuitions.”
“The former, as adding nothing through the predicate to the concept of the subject, but merely breaking it up into those constituent concepts that have all along been thought in it, although confusedly, can also be entitled explicative. The latter, on the other hand, add to the concept of the subject a predicate which has not been in any wise thought in it, and which no analysis could possibly extract from it; and they may therefore be entitled ampliative.”
“But in a priori synthetic judgments this help is entirely lacking. [I do not here have the advantage of looking around in the field of experience. ] Upon what, then, am I to rely, when I seek to go beyond the concept A, and to know that another concept B is connected with it? Through what is the synthesis made possible?”
“Let us take the proposition, ‘Everything which happens has its cause’. In the concept of ‘something which happens’, I do indeed think an existence which is preceded by a time, etc. , and from this concept analytic judgments may be obtained. But the concept of a ‘cause’ lies entirely outside the other concept, and signifies something different from ‘that which happens’, and is not therefore in any way contained in this latter representation.”
“How come I then to predicate of that which happens something quite different, and to apprehend that the concept of cause, though not contained in it, yet belongs, and indeed necessarily belongs to it?”
“What is here the unknown = X which gives support to the understanding when it believes that it can discover outside the concept A a predicate B foreign to this concept, which it yet at the same time considers to be connected with it?”
“It cannot be experience, because the suggested principle has connected the second representation with the first, not only with greater universality, but also with the character of necessity, and therefore completely a priori and on the basis of mere concepts.”
“1. All mathematical judgments, without exception, are synthetic.”
“First of all, it has to be noted that mathematical propositions, strictly so called, are always judgments a priori, not empirical; because they carry with them necessity, which cannot be derived from experience.”
“2. Natural science (physics) contains a priori synthetic judgments as principles. I need cite only two such judgments: that in all changes of the material world the quantity of matter remains unchanged; and that in all communication of motion, action and reaction must always be equal. Both propositions, it is evident, are not only necessary, and therefore in their origin a priori, but also synthetic. For in the concept of matter I do not think its permanence, but only its presence in the space which it occupies. I go outside and beyond the concept of matter, joining to it a priori in thought something which I have not thought in it. The proposition is not, therefore, analytic, but synthetic, and yet is thought a priori; and so likewise are the other propositions of the pure part of natural science.”
“3. Metaphysics, even if we look upon it as having hitherto failed in all its endeavours, is yet, owing to the nature of human reason, a quite indispensable science, and ought to contain a priori synthetic knowledge. For its business is not merely to analyse concepts which we make for ourselves a - priori of things, and thereby to clarify them analytically, but to extend our a priori knowledge. And for this purpose we must employ principles which add to the given concept something that was not contained in it, and through a priori synthetic judgments venture out so far that experience is quite unable to follow us, as, for instance, in the proposition, that the world must have a first beginning, and such like. Thus metaphysics consists, at least in intention, entirely of a priori synthetic propositions.”
“Now the proper problem of pure reason is contained in the question: How are a priori synthetic judgments possible?”
“Yet, in a certain sense, this kind of knowledge is to be looked upon as given; that is to say, metaphysics actually exists, if not as a science, yet still as natural disposition (metaphysica naturalis). For human reason, without being moved merely by the idle desire for extent and variety of knowledge, proceeds impetuously, driven on by an inward need, to questions such as cannot be answered by any empirical employment of reason, or by principles thence derived.”
“Thus in all men, as soon as their reason has become ripe for speculation, there has always existed and will always continue to exist some kind of metaphysics. And so we have the question:
How is metaphysics, as natural disposition, possible?”
“that is, how from the nature of universal human reason do those questions arise which pure reason propounds to itself, and which it is impelled by its own need to answer as best it can?”
“How is metaphysics, as science, possible?”
“Thus the critique of reason, in the end, necessarily leads to scientific knowledge; while its dogmatic employment, on the other hand, lands us in dogmatic assertions to which other assertions, equally specious, can always be opposed – that is, in scepticism.”
“When once reason has learnt completely to understand its own power in respect of objects which can be presented to it in experience, it should easily be able to determine, with completeness and certainty, the extent and the limits of its attempted employment beyond the bounds of all experience.”
“We may, then, and indeed we must, regard as abortive all attempts, hitherto made, to establish a metaphysic dogmatically. For the analytic part in any such attempted system, namely, the mere analysis of the concepts that inhere in our reason a priori, is by no means the aim of, but only a preparation for, metaphysics proper, that is, the extension of its a - priori synthetic knowledge.”
“For reason is the faculty which supplies the principles of a priori knowledge. Pure reason is, therefore, that which contains the principles whereby we know anything absolutely a priori.”
“An organon of pure reason would be the sum-total of those principles according to which all modes of pure a priori knowledge can be acquired and actually brought into being.”
“The exhaustive application of such an organon would give rise to a system of pure reason.”
“But as this would be asking rather much, and as it is still doubtful whether, and in what cases, any extension of our knowledge be here possible, we can regard a science of the mere examination of pure reason, of its sources and limits, as the propaedeutic to the system of pure reason.”
“As such, it should be called a critique, not a doctrine, of pure reason. Its utility, in speculation, ought properly to be only negative, not to extend, but only to clarify our reason, and keep it free from errors – which is already a very great gain.”
“I entitle transcendental all knowledge which is occupied not so much with objects as with the mode of our knowledge of objects in so far as this mode of knowledge is to be possible a priori. A system of such concepts might be entitled transcendental philosophy.”
“Its purpose is not to extend knowledge, but only to correct it, and to supply a touchstone of the value, or lack of value, of all a priori knowledge.”
“our subject-matter is not the nature of things, which is inexhaustible, but the understanding which passes judgment upon the nature of things; and this understanding, again, only in respect of its a priori knowledge.”
“Our critique must, indeed, supply a complete enumeration of all the fundamental concepts that go to constitute such pure knowledge.”
“What has chiefly to be kept in view in the division of such a science, is that no concepts be allowed to enter which contain in themselves anything empirical, or, in other words, that it consist in knowledge wholly a priori.”
“If we are to make a systematic division of the science which we are engaged in presenting, it must have first a doctrine of the elements, and secondly, a doctrine of the method of pure reason.”
“Each of these chief divisions will have its subdivisions, but the grounds of these we are not yet in a position to explain. By way of introduction or anticipation we need only say that there are two stems of human knowledge, namely, sensibility and understanding, which perhaps spring from a common, but to us unknown, root.”
“Through the former, objects are given to us; through the latter, they are thought.”
“Now in so far as sensibility may be found to contain a priori representations constituting the condition under which objects are given to us, it will belong to transcendental philosophy. And since the conditions under which alone the objects of human knowledge are given must precede those under which they are thought, the transcendental doctrine of sensibility will constitute the first part of the science of the elements.”