But if we consider these principles of the pure understanding in relation to their origin, we shall find them to be anything rather than cognitions from conceptions. For they would not even be possible a priori, if we could not rely on the assistance of pure intuition (in mathematics), or on that of the conditions of a possible experience. That everything that happens has a cause, cannot be concluded from the general conception of that which happens; on the contrary the principle of causality instructs us as to the mode of obtaining from that which happens a determinate empirical conception.
Synthetical cognitions from conceptions the understanding cannot supply, and they alone are entitled to be called principles. At the same time, all general propositions may be termed comparative principles.
It has been a long-cherished wish — that (who knows how late), may one day, be happily accomplished — that the principles of the endless variety of civil laws should be investigated and exposed; for in this way alone can we find the secret of simplifying legislation. But in this case, laws are nothing more than limitations of our freedom upon conditions under which it subsists in perfect harmony with itself; they consequently have for their object that which is completely our own work, and of which we ourselves may be the cause by means of these conceptions. But how objects as things in themselves — how the nature of things is subordinated to principles and is to be determined according to conceptions, is a question which it seems well nigh impossible to answer. Be this, however, as it may — for on this point our investigation is yet to be made — it is at least manifest from what we have said that cognition from principles is something very different from cognition by means of the understanding, which may indeed precede other cognitions in the form of a principle, but in itself — in so far as it is synthetical — is neither based upon mere thought, nor contains a general proposition drawn from conceptions alone shall comprehend
The understanding may be a faculty for the production of unity of phenomena by virtue of rules; the reason is a faculty for the production of unity of rules (of the understanding) under principles. Reason, therefore, never applies directly to experience, or to any sensuous object; its object is, on the contrary, the understanding, to the manifold cognition of which it gives a unity a priori by means of conceptions — a unity which may be called rational unity, and which is of a nature very different from that of the unity produced by the understanding.
The above is the general conception of the faculty of reason, in so far as it has been possible to make it comprehensible in the absence of examples. These will be given in the sequel.
B. Of the Logical Use of Reason.
A distinction is commonly made between that which is immediately cognized and that which is inferred or concluded. That in a figure which is bounded by three straight lines there are three angles, is an immediate cognition; but that these angles are together equal to two right angles, is an inference or conclusion. Now, as we are constantly employing this mode of thought and have thus become quite accustomed to it, we no longer remark the above distinction, and, as in the case of the so-called deceptions of sense, consider as immediately perceived, what has really been inferred. In every reasoning or syllogism, there is a fundamental proposition, afterwards a second drawn from it, and finally the conclusion, which connects the truth in the first with the truth in the second — and that infallibly. If the judgement concluded is so contained in the first proposition that it can be deduced from it without the meditation of a third notion, the conclusion is called immediate (consequentia immediata); I prefer the term conclusion of the understanding. But if, in addition to the fundamental cognition, a second judgement is necessary for the production of the conclusion, it is called a conclusion of the reason. In the proposition: All men are mortal, are contained the propositions: Some men are mortal, Nothing that is not mortal is a man, and these are therefore immediate conclusions from the first. On the other hand, the proposition: all the learned are mortal, is not contained in the main proposition (for the conception of a learned man does not occur in it), and it can be deduced from the main proposition only by means of a mediating judgement.
In every syllogism I first cogitate a rule (the major) by means of the understanding. In the next place I subsume a cognition under the condition of the rule (and this is the minor) by means of the judgement. And finally I determine my cognition by means of the predicate of the rule (this is the conclusio), consequently, I determine it a priori by means of the reason. The relations, therefore, which the major proposition, as the rule, represents between a cognition and its condition, constitute the different kinds of syllogisms. These are just threefold — analogously with all judgements, in so far as they differ in the mode of expressing the relation of a cognition in the understanding — namely, categorical, hypothetical, and disjunctive.
When as often happens, the conclusion is a judgement which may follow from other given judgements, through which a perfectly different object is cogitated, I endeavour to discover in the understanding whether the assertion in this conclusion does not stand under certain conditions according to a general rule. If I find such a condition, and if the object mentioned in the conclusion can be subsumed under the given condition, then this conclusion follows from a rule which is also valid for other objects of cognition. From this we see that reason endeavours to subject the great variety of the cognitions of the understanding to the smallest possible number of principles (general conditions), and thus to produce in it the highest unity.
C. Of the Pure Use of Reason.
Can we isolate reason, and, if so, is it in this case a peculiar source of conceptions and judgements which spring from it alone, and through which it can be applied to objects; or is it merely a subordinate faculty, whose duty it is to give a certain form to given cognitions — a form which is called logical, and through which the cognitions of the understanding are subordinated to each other, and lower rules to higher (those, to wit, whose condition comprises in its sphere the condition of the others), in so far as this can be done by comparison? This is the question which we have at present to answer. Manifold variety of rules and unity of principles is a requirement of reason, for the purpose of bringing the understanding into complete accordance with itself, just as understanding subjects the manifold content of intuition to conceptions, and thereby introduces connection into it. But this principle prescribes no law to objects, and does not contain any ground of the possibility of cognizing or of determining them as such, but is merely a subjective law for the proper arrangement of the content of the understanding. The purpose of this law is, by a comparison of the conceptions of the understanding, to reduce them to the smallest possible number, although, at the same time, it does not justify us in demanding from objects themselves such a uniformity as might contribute to the convenience and the enlargement of the sphere of the understanding, or in expecting that it will itself thus receive from them objective validity. In one word, the question is: “does reason in itself, that is, does pure reason contain a priori synthetical principles and rules, and what are those principles?”
The formal and logical procedure of reason in syllogisms gives us sufficient information in regard to the ground on which the transcendental principle of reason in its pure synthetical cognition will rest.
1. Reason, as observed in the syllogistic process, is not applicable to intuitions, for the purpose of subjecting them to rules — for this is the province of the understanding with its categories — but to conceptions and judgements. If pure reason does apply to objects and the intuition of them, it does so not immediately, but mediately — through the understanding and its judgements, which have a direct relation to the senses and their intuition, for the purpose of determining their objects. The unity of reason is therefore not the unity of a possible experience, but is essentially different from this unity, which is that of the understanding. That everything which happens has a cause, is not a principle cognized and prescribed by reason. This principle makes the unity of experience possible and borrows nothing from reason, which, without a reference to possible experience, could never have produced by means of mere conceptions any such synthetical unity.
2. Reason, in its logical use, endeavours to discover the general condition of its judgement (the conclusion), and a syllogism is itself nothing but a judgement by means of the subsumption of its condition