Notwithstanding the pressing necessity which reason feels, to form some presupposition that shall serve the understanding as a proper basis for the complete determination of its conceptions, the idealistic and factitious nature of such a presupposition is too evident to allow reason for a moment to persuade itself into a belief of the objective existence of a mere creation of its own thought. But there are other considerations which compel reason to seek out some resting place in the regress from the conditioned to the unconditioned, which is not given as an actual existence from the mere conception of it, although it alone can give completeness to the series of conditions. And this is the natural course of every human reason, even of the most uneducated, although the path at first entered it does not always continue to follow. It does not begin from conceptions, but from common experience, and requires a basis in actual existence. But this basis is insecure, unless it rests upon the immovable rock of the absolutely necessary. And this foundation is itself unworthy of trust, if it leave under and above it empty space, if it do not fill all, and leave no room for a why or a wherefore, if it be not, in one word, infinite in its reality.
If we admit the existence of some one thing, whatever it may be, we must also admit that there is something which exists necessarily. For what is contingent exists only under the condition of some other thing, which is its cause; and from this we must go on to conclude the existence of a cause which is not contingent, and which consequently exists necessarily and unconditionally. Such is the argument by which reason justifies its advances towards a primal being.
Now reason looks round for the conception of a being that may be admitted, without inconsistency, to be worthy of the attribute of absolute necessity, not for the purpose of inferring a priori, from the conception of such a being, its objective existence (for if reason allowed itself to take this course, it would not require a basis in given and actual existence, but merely the support of pure conceptions), but for the purpose of discovering, among all our conceptions of possible things, that conception which possesses no element inconsistent with the idea of absolute necessity. For that there must be some absolutely necessary existence, it regards as a truth already established. Now, if it can remove every existence incapable of supporting the attribute of absolute necessity, excepting one- this must be the absolutely necessary being, whether its necessity is comprehensible by us, that is, deducible from the conception of it alone, or not.
Now that, the conception of which contains a therefore to every wherefore, which is not defective in any respect whatever, which is all-sufficient as a condition, seems to be the being of which we can justly predicate absolute necessity- for this reason, that, possessing the conditions of all that is possible, it does not and cannot itself require any condition. And thus it satisfies, in one respect at least, the requirements of the conception of absolute necessity. In this view, it is superior to all other conceptions, which, as deficient and incomplete, do not possess the characteristic of independence of all higher conditions. It is true that we cannot infer from this that what does not contain in itself the supreme and complete condition- the condition of all other things- must possess only a conditioned existence; but as little can we assert the contrary, for this supposed being does not possess the only characteristic which can enable reason to cognize by means of an a priori conception the unconditioned and necessary nature of its existence.
The conception of an ens realissimum is that which best agrees with the conception of an unconditioned and necessary being. The former conception does not satisfy all the requirements of the latter; but we have no choice, we are obliged to adhere to it, for we find that we cannot do without the existence of a necessary being; and even although we admit it, we find it out of our power to discover in the whole sphere of possibility any being that can advance wellgrounded claims to such a distinction.
The following is, therefore, the natural course of human reason. It begins by persuading itself of the existence of some necessary being. In this being it recognizes the characteristics of unconditioned existence. It then seeks the conception of that which is independent of all conditions, and finds it in that which is itself the sufficient condition of all other things- in other words, in that which contains all reality. But the unlimited all is an absolute unity, and is conceived by the mind as a being one and supreme; and thus reason concludes that the Supreme Being, as the primal basis of all things, possesses an existence which is absolutely necessary.
This conception must be regarded as in some degree satisfactory, if we admit the existence of a necessary being, and consider that there exists a necessity for a definite and final answer to these questions. In such a case, we cannot make a better choice, or rather we have no choice at all, but feel ourselves obliged to declare in favour of the absolute unity of complete reality, as the highest source of the possibility of things. But if there exists no motive for coming to a definite conclusion, and we may leave the question unanswered till we have fully weighed both sides- in other words, when we are merely called upon to decide how much we happen to know about the question, and how much we merely flatter ourselves that we know- the above conclusion does not appear to be so great advantage, but, on the contrary, seems defective in the grounds upon which it is supported.
For, admitting the truth of all that has been said, that, namely, the inference from a given existence (my own, for example) to the existence of an unconditioned and necessary being is valid and unassailable; that, in the second place, we must consider a being which contains all reality, and consequently all the conditions of other things, to be absolutely unconditioned; and admitting too, that we have thus discovered the conception of a thing to which may be attributed, without inconsistency, absolute necessity- it does not follow from all this that the conception of a limited being, in which the supreme reality does not reside, is therefore incompatible with the idea of absolute necessity. For, although I do not discover the element of the unconditioned in the conception of such a being- an element which is manifestly existent in the sum-total of all conditions- I am not entitled to conclude that its existence is therefore conditioned; just as I am not entitled to affirm, in a hypothetical syllogism, that where a certain condition does not exist (in the present, completeness, as far as pure conceptions are concerned), the conditioned does not exist either. On the contrary, we are free to consider all limited beings as likewise unconditionally necessary, although we are unable to infer this from the general conception which we have of them. Thus conducted, this argument is incapable of giving us the least notion of the properties of a necessary being, and must be in every respect without result.
This argument continues, however, to possess a weight and an authority, which, in spite of its objective insufficiency, it has never been divested of. For, granting that certain responsibilities lie upon us, which, as based on the ideas of reason, deserve to be respected and submitted to, although they are incapable of a real or practical application to our nature, or, in other words, would be responsibilities without motives, except upon the supposition of a Supreme Being to give effect and influence to the practical laws: in such a case we should be bound to obey our conceptions, which, although objectively insufficient, do, according to the standard of reason, preponderate over and are superior to any claims that may be advanced from any other quarter. The equilibrium of doubt would in this case be destroyed by a practical addition; indeed, Reason would be compelled to condemn herself, if she refused to comply with the demands of the judgement, no superior to which we know- however defective her understanding of the grounds of these demands might be.
This argument, although in fact transcendental, inasmuch as it rests upon the intrinsic insufficiency of the contingent, is so simple and natural, that the commonest understanding can appreciate its value. We see things around us change, arise, and pass away; they, or their condition, must therefore have a cause. The same demand must again be made of the cause itself- as a datum of experience. Now it is natural that we should place the highest causality just where we place supreme causality, in that being, which contains the conditions of all possible effects, and the conception of which is so simple as that of an all-embracing reality. This highest cause, then, we regard as absolutely necessary, because we find it absolutely necessary to rise to it, and do not discover any reason for proceeding beyond it. Thus, among all nations, through the darkest polytheism glimmer some faint sparks of monotheism, to which these idolaters have been led, not from reflection and profound thought, but by the study and natural progress of the common understanding.
There are only three modes of proving the existence of a Deity, on the grounds of speculative reason.
All the paths conducting to this end begin either from determinate experience and the peculiar constitution of the world of sense, and rise, according to the laws of causality, from it to the highest cause existing apart from the world- or from a purely indeterminate experience, that is, some empirical existence- or abstraction is made of all experience, and the existence of a supreme cause is concluded from a priori conceptions alone. The first is the physicotheological argument, the second the cosmological, the third the ontological. More there are not, and more there cannot be.
I shall show it is as unsuccessful on the one path- the empirical- as on the other- the transcendental- and that it stretches its wings in vain, to soar beyond the world of sense by the mere might of speculative thought. As regards the order in which we must discuss those arguments, it will be exactly the reverse of that in which reason, in the progress of its development, attains to them- the order in which they are placed above. For it will be made manifest to the reader that, although experience presents the occasion and the starting-point, it is the transcendental idea of reason which guides it in its pilgrimage and is the goal of all its struggles. I shall therefore begin with an examination of the transcendental argument, and afterwards inquire what additional strength has accrued to this mode of proof from the addition of the empirical element.