Immanuel Kant's Critique of Pure Reason, translated by Norman Kemp Smith









OUR knowledge springs from two fundamental sources of the mind; the first is the capacity of receiving representations (receptivity for impressions), the second is the power of knowing an object through these representations (spontaneity [in the production] of concepts). Through the first an object is given to us, through the second the object is thought in relation to that [given] 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 may be either pure or empirical. When they contain sensation (which presupposes the actual presence of the object), they are empirical. When there is no mingling of sensation with the representation,they are pure. Sensation may be entitled the material of sensible knowledge. Pure intuition, therefore, contains only the form under which something is intuited; the pure concept only the form of the thought of an object in general. Pure intuitions or pure concepts alone are possible a priori, empirical intuitions and empirical concepts only a posteriori. [93]

If the receptivity of our mind, its power of receiving representations in so far as it is in any wise affected, is to be entitled sensibility, then the mind's power of producing representations from itself, the spontaneity of knowledge, should be called the understanding. Our nature is 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 other hand, which enables us to think the object of sensible intuition is the understanding. To neither of these powers may a preference be given over 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, that is, to add the object to them in intuition, as to make our intuitions intelligible, that is, to bring them under concepts. These two powers or capacities cannot exchange their functions. The understanding can intuit nothing, the senses can think nothing. Only through their union can knowledge arise. But that is no reason for confounding the contribution of either with that of the other; rather is it 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, that is, aesthetic, from the science of the rules of the understanding in general, that is, logic.

Logic, again, can be treated in a twofold manner, either as logic of the general or as logic of the special employment of the understanding. The former contains the absolutely necessary rules of thought without which there can be no employment whatsoever of the understanding. It therefore treats of understanding without any regard to difference in the objects to which the understanding may be directed. The logic of the special employment of the understanding contains the rules of correct thinking as regards a certain kind of objects. The former may be called the logic of elements, the latter the organon of this or that science. The latter is commonly taught in the schools as a propaedeutic to the sciences, though, according to the actual procedure of human reason, it is what is obtained last of all, when the particular science [94] under question has been already brought to such completion that it requires only a few finishing touches to correct and perfect it. For the objects under consideration must already be known fairly completely before it can be possible to prescribe the rules according to which a science of them is to be obtained.

General logic is either pure or applied. In the former we abstract from all empirical conditions under which our understanding is exercised, i.e. from the influence of the senses, the play of imagination, the laws of memory, the force of habit, inclination, etc. , and so from all sources of prejudice, indeed from all causes from which this or that knowledge may arise or seem to arise. For they concern the understanding only in so far as it is being employed under certain circumstances, and to become acquainted with these circumstances experience is required. Pure general logic has to do, therefore, only with principles a priori, and is a canon of understanding and of reason, but only in respect of what is formal in their employment, be the content what it may, empirical or transcendental. General logic is called applied, when it is directed to the rules of the employment of understanding under the subjective empirical conditions dealt with by psychology. Applied logic has therefore empirical principles, although it is still indeed in so far general that it refers to the employment of the understanding without regard to difference in the objects. Consequently it is neither a canon of the understanding in general nor an organon of special sciences, but merely a cathartic of the common understanding.

In general logic, therefore, that part which is to constitute the pure doctrine of reason must be entirely separated from that which constitutes applied (though always still general) logic. The former alone is, properly speaking, a science, though indeed concise and dry, as the methodical exposition of a doctrine of the elements of the understanding is bound to be. There are therefore two rules which logicians must always bear in mind, in dealing with pure general logic:

1. As general logic, it abstracts from all content of the knowledge of understanding and from all differences in its objects, and deals with nothing but the mere form of thought. [95]

2. As pure logic, it has nothing to do with empirical principles, and does not, as has sometimes been supposed, borrow anything from psychology, which therefore has no influence whatever on the canon of the understanding. Pure logic is a body of demonstrated doctrine, and everything in it must be certain entirely a priori.

What I call applied logic (contrary to the usual meaning of this title, according to which it should contain certain exercises for which pure logic gives the rules) is a representation of the understanding and of the rules of its necessary employment in concreto, that is, under the accidental subjective conditions which may hinder or help its application, and which are all given only empirically. It treats of attention, its impediments and consequences, of the source of error, of the state of doubt, hesitation, and conviction, etc. Pure general logic stands to it in the same relation as pure ethics, which contains only the necessary moral laws of a free will in general, stands to the doctrine of the virtues strictly so called -- the doctrine which considers these laws under the limitations of the feelings, inclinations, and passions to which men are more or less subject. Such a doctrine can never furnish a true and demonstrated science, because, like applied logic, it depends on empirical and psychological principles.


General logic, as we have shown, abstracts from all content of knowledge, that is, from all relation of knowledge to the object, and considers only the logical form in the relation of any knowledge to other knowledge; that is, it treats of the form of thought in general. But since, as the Transcendental Aesthetic has shown, there are pure as well as empirical intuitions, a distinction might likewise be drawn between pure and empirical thought of objects. In that case we should have a logic in which we do not abstract from the entire content of knowledge. This other logic, which should contain solely the rules of the pure thought of an object, would exclude only those [96] modes of knowledge which have empirical content. It would also treat of the origin of the modes in which we know objects, in so far as that origin cannot be attributed to the objects. General logic, on the other hand, has nothing to do with the origin of knowledge, but only considers representations, be they originally a priori in ourselves or only empirically given, according to the laws which the understanding employs when, in thinking, it relates them to one another. It deals therefore only with that form which the understanding is able to impart to the representations, from whatever source they may have arisen.

And here I make a remark which the reader must bear well in mind, as it extends its influence over all that follows. Not every kind of knowledge a priori should be called transcendental, but that only by which we know that -- and how -- certain representations (intuitions or concepts) can be employed or are possible purely a priori. The term 'transcendental', that is to say, signifies such knowledge as concerns the a priori possibility of knowledge, or its a priori employment. Neither space nor any a priori geometrical determination of it is a transcendental representation; what can alone be entitled transcendental is the knowledge that these representations are not of empirical origin, and the possibility that they can yet relate a priori to objects of experience. The application of space to objects in general would likewise be transcendental, but, if restricted solely to objects of sense, it is empirical. The distinction between the transcendental and the empirical belongs therefore only to the critique of knowledge; it does not concern the relation of that knowledge to its objects.

In the expectation, therefore, that there may perhaps be concepts which relate a priori to objects, not as pure or sensible intuitions, but solely as acts of pure thought -- that is, as concepts which are neither of empirical nor of aesthetic origin -- we form for ourselves by anticipation the idea of a science of the knowledge which belongs to pure understanding and reason, whereby we think objects entirely a priori. Such a science, which should determine the origin, the scope, and [97] the objective validity of such knowledge, would have to be called transcendental logic, because, unlike general logic, which has to deal with both empirical and pure knowledge of reason, it concerns itself with the laws of understanding and of reason solely in so far as they relate a priori to objects.


The question, famed of old, by which logicians were supposed to be driven into a corner, obliged either to have recourse to a pitiful sophism, or to confess their ignorance and consequently the emptiness of their whole art, is the question: What is truth? The nominal definition of truth, that it is the agreement of knowledge with its object, is assumed as granted; the question asked is as to what is the general and sure criterion of the truth of any and every knowledge.

To know what questions may reasonably be asked is already a great and necessary proof of sagacity and insight. For if a question is absurd in itself and calls for an answer where none is required, it not only brings shame on the propounder of the question, but may betray an incautious listener into absurd answers, thus presenting, as the ancients said, the ludicrous spectacle of one man milking a he-goat and the other holding a sieve underneath.

If truth consists in the agreement of knowledge with its object, that object must thereby be distinguished from other objects; for knowledge is false, if it does not agree with the object to which it is related, even although it contains something which may be valid of other objects. Now a general criterion of truth must be such as would be valid in each and every instance of knowledge, however their objects may vary. It is obvious, however, that such a criterion [being general] cannot take account of the [varying] content of knowledge (relation to its [specific] object). But since truth concerns just this very content, it is quite impossible, and indeed absurd, to ask for a [98] general test of the truth of such content. A sufficient and at the same time general criterion of truth cannot possibly be given. Since we have already entitled the content of knowledge its matter, we must be prepared to recognize that of the truth of knowledge, so far as its matter is concerned, no general criterion can be demanded. Such a criterion would by its very nature be self-contradictory.

But, on the other hand, as regards knowledge in respect of its mere form (leaving aside all content), it is evident that logic, in so far as it expounds the universal and necessary rules of the understanding, must in these rules furnish criteria of truth. Whatever contradicts these rules is false. For the understanding would thereby be made to contradict its own general rules of thought, and so to contradict itself. These criteria, however, concern only the form of truth, that is, of thought in general; and in so far they are quite correct, but are not by themselves sufficient. For although our knowledge may be in complete accordance with logical demands, that is, may not contradict itself, it is still possible that it may be in contradiction with its object. The purely logical criterion of truth, namely, the agreement of knowledge with the general and formal laws of the understanding and reason, is a conditio sine qua non, and is therefore the negative condition of all truth. But further than this logic cannot go. It has no touchstone for the discovery of such error as concerns not the form but the content.

General logic resolves the whole formal procedure of the understanding and reason into its elements, and exhibits them as principles of all logical criticism of our knowledge. This part of logic, which may therefore be entitled analytic, yields what is at least the negative touchstone of truth. Its rules must be applied in the examination and appraising of the form of all knowledge before we proceed to determine whether their content contains positive truth in respect to their object. But since the mere form of knowledge, however completely it may be in agreement with logical laws, is far from being sufficient to determine the material (objective) truth of knowledge, no one can venture with the help of logic alone to judge regarding objects, or to make any assertion. We must first, independently of logic, obtain reliable information; only [99] then are we in a position to enquire, in accordance with logical laws, into the use of this information and its connection in a coherent whole, or rather to test it by these laws. There is, however, something so tempting in the possession of an art so specious, through which we give to all our knowledge, however uninstructed we may be in regard to its content, the form of understanding, that general logic, which is merely a canon of judgment, has been employed as if it were an organon for the actual production of at least the semblance of objective assertions, and has thus been misapplied. General logic, when thus treated as an organon, is called dialectic.

However various were the significations in which the ancients used 'dialectic' as the title for a science or art, we can safely conclude from their actual employment of it that with them it was never anything else than the logic of illusion. It was a sophistical art of giving to ignorance, and indeed to intentional sophistries, the appearance of truth, by the device of imitating the methodical thoroughness which logic prescribes, and of using its 'topic' to conceal the emptiness of its pretensions. Now it may be noted as a sure and useful warning, that general logic, if viewed as an organon, is always a logic of illusion, that is, dialectical. For logic teaches us nothing whatsoever regarding the content of knowledge, but lays down only the formal conditions of agreement with the understanding; and since these conditions can tell us nothing at all as to the objects concerned, any attempt to use this logic as an instrument (organon) that professes to extend and enlarge our knowledge can end in nothing but mere talk -- in which, with a certain plausibility, we maintain, or, if such be our choice, attack, any and every possible assertion.

Such instruction is quite unbecoming the dignity of philosophy. The title 'dialectic' has therefore come to be otherwise employed, and has been assigned to logic, as a critique of dialectical illusion. This is the sense in which it is to be understood in this work. [100]


In a transcendental logic we isolate the understanding -- as above, in the Transcendental Aesthetic, the sensibility -- separating out from our knowledge that part of thought which has its origin solely in the understanding. The employment of this pure knowledge depends upon the condition that objects to which it can be applied be given to us in intuition. In the absence of intuition all our knowledge is without objects, and therefore remains entirely empty. That part of transcendental logic which deals with the elements of the pure knowledge yielded by understanding, and the principles without which no object can be thought, is transcendental analytic. It is a logic of truth. For no knowledge can contradict it without at once losing all content, that is, all relation to any object, and therefore all truth. But since it is very tempting to use these pure modes of knowledge of the understanding and these principles by themselves, and even beyond the limits of experience, which alone can yield the matter (objects) to which those pure concepts of understanding can be applied, the understanding is led to incur the risk of making, with a mere show of rationality, a material use of its pure and merely formal principles, and of passing judgments upon objects without distinction -- upon objects which are not given to us, nay, perhaps cannot in any way be given. Since, properly, this transcendental analytic should be used only as a canon for passing judgment upon the empirical employment of the understanding, it is misapplied if appealed to as an organon of its general and unlimited application, and if consequently we venture, with the pure understanding alone, to judge synthetically, to affirm, and to decide regarding objects in general. The employment of the pure understanding then becomes dialectical. The second part of transcendental logic must therefore form a critique of this dialectical illusion, and is called transcendental dialectic, not as an art of producing such illusion dogmatically (an art unfortunately very commonly practiced by metaphysical jugglers), but as a critique of understanding and reason in respect of [101] their hyperphysical employment. It will expose the false, illusory character of those groundless pretensions, and in place of the high claims to discover and to extend knowledge merely by means of transcendental principles, it will substitute what is no more than a critical treatment of the pure understanding, for the guarding of it against sophistical illusion.

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