In the preceding remarks, we considered the changes in the world of sense as constituting a dynamical series, in which each member is subordinated to another- as its cause. Our present purpose is to avail ourselves of this series of states or conditions as a guide to an existence which may be the highest condition of all changeable phenomena, that is, to a necessary being. Our endeavour to reach, not the unconditioned causality, but the unconditioned existence, of substance. The series before us is therefore a series of conceptions, and not of intuitions (in which the one intuition is the condition of the other).
But it is evident that, as all phenomena are subject to change and conditioned in their existence, the series of dependent existences cannot embrace an unconditioned member, the existence of which would be absolutely necessary. It follows that, if phenomena were things in themselves, and- as an immediate consequence from this supposition- condition and conditioned belonged to the same series of phenomena, the existence of a necessary being, as the condition of the existence of sensuous phenomena, would be perfectly impossible.
An important distinction, however, exists between the dynamical and the mathematical regress. The latter is engaged solely with the combination of parts into a whole, or with the division of a whole into its parts; and therefore are the conditions of its series parts of the series, and to be consequently regarded as homogeneous, and for this reason, as consisting, without exception, of phenomena. If the former regress, on the contrary, the aim of which is not to establish the possibility of an unconditioned whole consisting of given parts, or of an unconditioned part of a given whole, but to demonstrate the possibility of the deduction of a certain state from its cause, or of the contingent existence of substance from that which exists necessarily, it is not requisite that the condition should form part of an empirical series along with the conditioned.
In the case of the apparent antinomy with which we are at present dealing, there exists a way of escape from the difficulty; for it is not impossible that both of the contradictory statements may be true in different relations. All sensuous phenomena may be contingent, and consequently possess only an empirically conditioned existence, and yet there may also exist a non-empirical condition of the whole series, or, in other words, a necessary being. For this necessary being, as an intelligible condition, would not form a member- not even the highest member- of the series; the whole world of sense would be left in its empirically determined existence uninterfered with and uninfluenced. This would also form a ground of distinction between the modes of solution employed for the third and fourth antinomies. For, while in the consideration of freedom in the former antinomy, the thing itself- the cause (substantia phaenomenon)- was regarded as belonging to the series of conditions, and only its causality to the intelligible world- we are obliged in the present case to cogitate this necessary being as purely intelligible and as existing entirely apart from the world of sense (as an ens extramundanum); for otherwise it would be subject to the phenomenal law of contingency and dependence.
In relation to the present problem, therefore, the regulative principle of reason is that everything in the sensuous world possesses an empirically conditioned existence- that no property of the sensuous world possesses unconditioned necessity- that we are bound to expect, and, so far as is possible, to seek for the empirical condition of every member in the series of conditions- and that there is no sufficient reason to justify us in deducing any existence from a condition which lies out of and beyond the empirical series, or in regarding any existence as independent and self-subsistent; although this should not prevent us from recognizing the possibility of the whole series being based upon a being which is intelligible, and for this reason free from all empirical conditions.
But it has been far from my intention, in these remarks, to prove the existence of this unconditioned and necessary being, or even to evidence the possibility of a purely intelligible condition of the existence or all sensuous phenomena. As bounds were set to reason, to prevent it from leaving the guiding thread of empirical conditions and losing itself in transcendent theories which are incapable of concrete presentation; so it was my purpose, on the other band, to set bounds to the law of the purely empirical understanding, and to protest against any attempts on its part at deciding on the possibility of things, or declaring the existence of the intelligible to be impossible, merely on the ground that it is not available for the explanation and exposition of phenomena. It has been shown, at the same time, that the contingency of all the phenomena of nature and their empirical conditions is quite consistent with the arbitrary hypothesis of a necessary, although purely intelligible condition, that no real contradiction exists between them and that, consequently, both may be true. The existence of such an absolutely necessary being may be impossible; but this can never be demonstrated from the universal contingency and dependence of sensuous phenomena, nor from the principle which forbids us to discontinue the series at some member of it, or to seek for its cause in some sphere of existence beyond the world of nature. Reason goes its way in the empirical world, and follows, too, its peculiar path in the sphere of the transcendental.
The sensuous world contains nothing but phenomena, which are mere representations, and always sensuously conditioned; things in themselves are not, and cannot be, objects to us. It is not to be wondered at, therefore, that we are not justified in leaping from some member of an empirical series beyond the world of sense, as if empirical representations were things in themselves, existing apart from their transcendental ground in the human mind, and the cause of whose existence may be sought out of the empirical series. This would certainly be the case with contingent things; but it cannot be with mere representations of things, the contingency of which is itself merely a phenomenon and can relate to no other regress than that which determines phenomena, that is, the empirical. But to cogitate an intelligible ground of phenomena, as free, moreover, from the contingency of the latter, conflicts neither with the unlimited nature of the empirical regress, nor with the complete contingency of phenomena. And the demonstration of this was the only thing necessary for the solution of this apparent antinomy. For if the condition of every conditioned- as regards its existence- is sensuous, and for this reason a part of the same series, it must be itself conditioned, as was shown in the antithesis of the fourth antinomy. The embarrassments into which a reason, which postulates the unconditioned, necessarily falls, must, therefore, continue to exist; or the unconditioned must be placed in the sphere of the intelligible. In this way, its necessity does not require, nor does it even permit, the presence of an empirical condition: and it is, consequently, unconditionally necessary.
The empirical employment of reason is not affected by the assumption of a purely intelligible being; it continues its operations on the principle of the contingency of all phenomena, proceeding from empirical conditions to still higher and higher conditions, themselves empirical. just as little does this regulative principle exclude the assumption of an intelligible cause, when the question regards merely the pure employment of reason- in relation to ends or aims. For, in this case, an intelligible cause signifies merely the transcendental and to us unknown ground of the possibility of sensuous phenomena, and its existence, necessary and independent of all sensuous conditions, is not inconsistent with the contingency of phenomena, or with the unlimited possibility of regress which exists in the series of empirical conditions.