possible totality of conditions, and, conversely, the totality of conditions is itself always unconditioned; a pure rational conception in general can be defined and explained by means of the conception of the unconditioned, in so far as it contains a basis for the synthesis of the conditioned.
To the number of modes of relation which the understanding cogitates by means of the categories, the number of pure rational conceptions will correspond. We must therefore seek for, first, an unconditioned of the categorical synthesis in a subject; secondly, of the hypothetical synthesis of the members of a series; thirdly, of the disjunctive synthesis of parts in a system.
There are exactly the same number of modes of syllogisms, each of which proceeds through prosyllogisms to the unconditioned — one to the subject which cannot be employed as predicate, another to the presupposition which supposes nothing higher than itself, and the third to an aggregate of the members of the complete division of a conception. Hence the pure rational conceptions of totality in the synthesis of conditions have a necessary foundation in the nature of human reason — at least as modes of elevating the unity of the understanding to the unconditioned. They may have no valid application, corresponding to their transcendental employment, in concreto, and be thus of no greater utility than to direct the understanding how, while extending them as widely as possible, to maintain its exercise and application in perfect consistence and harmony.
But, while speaking here of the totality of conditions and of the unconditioned as the common title of all conceptions of reason, we again light upon an expression which we find it impossible to dispense with, and which nevertheless, owing to the ambiguity attaching to it from long abuse, we cannot employ with safety. The word absolute is one of the few words which, in its original signification, was perfectly adequate to the conception it was intended to convey — a conception which no other word in the same language exactly suits, and the loss — or, which is the same thing, the incautious and loose employment — of which must be followed by the loss of the conception itself. And, as it is a conception which occupies much of the attention of reason, its loss would be greatly to the detriment of all transcendental philosophy. The word absolute is at present frequently used to denote that something can be predicated of a thing considered in itself and intrinsically. In this sense absolutely possible would signify that which is possible in itself (interne)- which is, in fact, the least that one can predicate of an object. On the other hand, it is sometimes employed to indicate that a thing is valid in all respects — for example, absolute sovereignty. Absolutely possible would in this sense signify that which is possible in all relations and in every respect; and this is the most that can be predicated of the possibility of a thing. Now these significations do in truth frequently coincide. Thus, for example, that which is intrinsically impossible, is also impossible in all relations, that is, absolutely impossible. But in most cases they differ from each other toto caelo, and I can by no means conclude that, because a thing is in itself possible, it is also possible in all relations, and therefore absolutely. Nay, more, I shall in the sequel show that absolute necessity does not by any means depend on internal necessity, and that, therefore, it must not be considered as synonymous with it. Of an opposite which is intrinsically impossible, we may affirm that it is in all respects impossible, and that, consequently, the thing itself, of which this is the opposite, is absolutely necessary; but I cannot reason conversely and say, the opposite of that which is absolutely necessary is intrinsically impossible, that is, that the absolute necessity of things is an internal necessity. For this internal necessity is in certain cases a mere empty word with which the least conception cannot be connected, while the conception of the necessity of a thing in all relations possesses very peculiar determinations. Now as the loss of a conception of great utility in speculative science cannot be a matter of indifference to the philosopher, I trust that the proper determination and careful preservation of the expression on which the conception depends will likewise be not indifferent to him.
In this enlarged signification, then, shall I employ the word absolute, in opposition to that which is valid only in some particular respect; for the latter is restricted by conditions, the former is valid without any restriction whatever.
Now the transcendental conception of reason has for its object nothing else than absolute totality in the synthesis of conditions and does not rest satisfied till it has attained to the absolutely, that is, in all respects and relations, unconditioned. For pure reason leaves to the understanding everything that immediately relates to the object of intuition or rather to their synthesis in imagination. The former restricts itself to the absolute totality in the employment of the conceptions of the understanding and aims at carrying out the synthetical unity which is cogitated in the category, even to the unconditioned. This unity may hence be called the rational unity of phenomena, as the other, which the category expresses, may be termed the unity of the understanding. Reason, therefore, has an immediate relation to the use of the understanding, not indeed in so far as the latter contains the ground of possible experience (for the conception of the absolute totality of conditions is not a conception that can be employed in experience, because no experience is unconditioned), but solely for the purpose of directing it to a certain unity, of which the understanding has no conception, and the aim of which is to collect into an absolute whole all acts of the understanding. Hence the objective employment of the pure conceptions of reason is always transcendent, while that of the pure conceptions of the understanding must, according to their nature, be always immanent, inasmuch as they are limited to possible experience.
I understand by idea a necessary conception of reason, to which no corresponding object can be discovered in the world of sense. Accordingly, the pure conceptions of reason at present under consideration are transcendental ideas. They are conceptions of pure reason, for they regard all empirical cognition as determined by means of an absolute totality of conditions. They are not mere fictions, but natural and necessary products of reason, and have hence a necessary relation to the whole sphere of the exercise of the understanding. And, finally, they are transcendent, and overstep the limits of all experiences, in which, consequently, no object can ever be presented that would be perfectly adequate to a transcendental idea. When we use the word idea, we say, as regards its object (an object of the pure understanding), a great deal, but as regards its subject (that is, in respect of its reality under conditions of experience), exceedingly little, because the idea, as the conception of a maximum, can never be completely and adequately presented in concreto. Now, as in the merely speculative employment of reason the latter is properly the sole aim, and as in this case the approximation to a conception, which is never attained in practice, is the same thing as if the conception were non-existent — it is commonly said of the conception of this kind, “it is only an idea.” So we might very well say, “the absolute totality of all phenomena is only an idea,” for, as we never can present an adequate representation of it, it remains for us a problem incapable of solution. On the other hand, as in the practical use of the understanding we have only to do with action and practice according to rules, an idea of pure reason can always be given really in concreto, although only partially, nay, it is the indispensable condition of all practical employment of reason. The practice or execution of the idea is always limited and defective, but nevertheless within indeterminable boundaries, consequently always under the influence of the conception of an absolute perfection. And thus the practical idea is always in the highest degree fruitful, and in relation to real actions indispensably necessary. In the idea, pure reason possesses even causality and the power of producing that which its conception contains. Hence we cannot say of wisdom, in a disparaging way, “it is only an idea.” For, for the very reason that it is the idea of the necessary unity of all possible aims, it must be for all practical exertions and endeavours the primitive condition and rule — a rule which, if not constitutive, is at least limitative.
Now, although we must say of the transcendental conceptions of reason, “they are only ideas,” we must not, on this account, look upon them as superfluous and nugatory. For, although no object can be determined by them, they can be of great utility, unobserved and at the basis of the edifice of the understanding, as the canon for its extended and self-consistent exercise — a canon which, indeed, does not enable it to cognize more in an object than it would cognize by the help of its own conceptions, but which guides it more securely in its cognition. Not to mention that they perhaps render possible a transition from our conceptions of nature and the non-ego to the practical conceptions, and thus produce for even ethical