It is surely extremely strange that, as soon as we suppose that something exists, we cannot avoid the conclusion that something exists necessarily. On this quite natural, though by no means, therefore, certain conclusion, rests the whole cosmological argument. On the other side, I may take any concept of anything, and I find that its existence has never to be represented by me as absolutely necessary, nay, that nothing prevents me, whatever may exist, from thinking its non-existence. I may, therefore, have to admit something necessary as the condition of existing things in general, but I need not think any single thing as necessary in itself. In other words I can never complete the regressus to the conditions of existence without admitting a necessary Being, but I can never begin with such a Being.
If, therefore, I am obliged to think something necessary for all existing things, and at the same time am not justified in thinking of anything as in itself necessary, the conclusion is inevitable: that necessity and contingency do not concern things themselves, for otherwise there would be a contradiction, and that therefore neither of the two principles can be objective; but that they may possibly be subjective principles of reason only, according to which, on one side, we have to find for all that is given as existing, something that is necessary, and thus never to stop except when we have reached an a priori complete explanation; while on the other we must never hope for that completion, that is, never admit anything empirical as unconditioned, and thus dispense with its further derivation. In that sense both principles as purely heuristic and regulative, and affecting the formal interests of reason only, may well stand side by side. For the one tells us that we ought to philosophise on nature as if there was a necessary first cause for everything that exists, if only in order to introduce systematical unity into our knowledge, by always looking for such an idea as an imagined highest cause. The other warns us against mistaking any single determination concerning the existence of things for such a highest cause, i.e. for something absolutely necessary, and bids us to keep the way always open for further derivation, and to treat it always as conditioned. If, then, everything that is perceived in things has to be considered by us as only conditionally necessary, nothing that is empirically given can ever be considered as absolutely necessary.
It follows from this that the absolutely necessary must be accepted as outside the world, because it is only meant to serve as a principle of the greatest possible unity of phenomena, of which it is the highest cause, and that it can never be reached in the world, because the second rule bids you always to consider all empirical causes of that unity as derived.
The philosophers of antiquity considered all form in nature as contingent, but matter, according to the judgment of common reason, as primitive and necessary. If, however, they had considered matter, not relatively as the substratum of phenomena, but as existing by itself, the idea of absolute necessity would have vanished at once, for there is nothing that binds reason absolutely to that existence, but reason can at any time and without contradiction remove it in thought, and it was in thought only that it could claim absolute necessity. The ground of this persuasion must therefore have been a certain regulative principle. And so it is; for extension and impermeability (which together constitute the concept of matter) furnish the highest empirical principle of the unity of phenomena, and possess, so far as this principle is empirically unconditioned, the character of a regulative principle. Nevertheless, as every determination of matter, which constitutes its reality, and hence the impermeability of matter also, is an effect (action) which must have a cause, and therefore be itself derived, matter is not adequate to the idea of a necessary Being, as a principle of all derived unity, because every one of its real qualities is derived and, therefore, conditionally necessary only, so that it could be removed, and with it would be removed the whole existence of matter. If this were not so, we should have reached the highest cause of unity, empirically, which is forbidden by the second regulative principle. It follows from all this that matter and everything in general that belongs to the world are not fit for the idea of a necessary original Being, as a mere principle of the greatest empirical unity, but that we must place it outside the world. In that case there is no reason why we should not simply derive the phenomena of the world and their existence from other phenomena, as if there were no necessary Being at all, while at the same time we might always strive towards the completeness of that derivation, just as if such a Being, as the highest cause, were presupposed.
The ideal of the Supreme Being is therefore, according to these remarks, nothing but a regulative principle of reason, which obliges us to consider all connection in the world as if it arose from an all-sufficient necessary cause, in order to found on it the rule of a systematical unity necessary according to general laws for the explanation of the world; it does not involve the assertion of an existence necessary by itself. It is impossible, however, at the same time, to escape from a transcendental subreptio, which leads us to represent that formal principle as constitutive, and to think that unity as hypostasised. It is the same with space. Space, though it is only a principle of sensibility, yet serves originally to make all forms possible, these being only limitations of it. For that very reason, however, it is mistaken for something absolutely necessary and independent, nay, for an object a priori existing in itself. It is the same here, and as this systematical unity of nature can in no wise become the principle of the empirical use of our reason, unless we base it on the idea of an ens realissimum as the highest cause, it happens quite naturally that we thus represent that idea as a real object, and that object again, as it is the highest condition, as necessary. Thus a regulative principle has been changed into a constitutive principle, which substitution becomes evident at once because, as soon as I consider that highest Being, which with regard to the world was absolutely (unconditionally) necessary, as a thing by itself, that necessity cannot be conceived, and can therefore have existed in my reason as a formal condition of thought only, and not as a material and substantial condition of existence.
The Ideal of Pure Reason
Section VI
Of the Impossibility of the Physico-theological Proof
If, then, neither the concept of things in general, nor the experience of any existence in general, can satisfy our demands, there still remains one way open, namely, to try whether any definite experience, and consequently that of things in the world as it is, their constitution and disposition, may not supply a proof which could give us the certain conviction of the existence of a Supreme Being. Such a proof we should call physico-theological. If that, however, should prove impossible too, then it is clear that no satisfactory proof whatever, from merely speculative reason, is possible, in support of the existence of a Being, corresponding to our transcendental idea.
After what has been said already, it will be easily understood that we may expect an easy and complete answer to this question. For how could there ever be an experience that should be adequate to an idea? It is the very nature of an idea that no experience can ever be adequate to it. The transcendental idea of a necessary and all-sufficient original Being is so overwhelming, so high above everything empirical, which is always conditioned, that we can never find in experience enough material to fill such a concept, and can only grope about among things conditioned, looking in vain for the unconditioned, of which no rule of any empirical synthesis can ever give us an example, or even show the way towards it.
If the highest Being should stand itself in that chain of conditions, it would be a link in the series, and would, exactly like the lower links, above which it is placed, require further investigation with regard to its own still higher cause. If, on the contrary, we mean to separate it from that chain, and, as a purely intelligible Being, not comprehend it in the series of natural causes, what bridge is then open for reason to reach it, considering that all rules determining the transition from effect to cause, nay, all synthesis and extension of our knowledge in general, refer to nothing but possible exp
erience, and therefore to the objects of the world of sense only, and are valid nowhere else?
This present world presents to us so immeasurable a stage of variety, order, fitness, and beauty, whether we follow it up in the infinity of space or in its unlimited division, that even with the little knowledge which our poor understanding has been able to gather, all language, with regard to so many and inconceivable wonders, loses its vigour, all numbers their power of measuring, and all our thoughts their necessary determination; so that our judgment of the whole is lost in a speechless, but all the more eloquent astonishment. Everywhere we see a chain of causes and effects, of means and ends, of order in birth and death, and as nothing has entered by itself into the state in which we find it, all points to another thing as its cause. As that cause necessitates the same further enquiry, the whole universe would thus be lost in the abyss of nothing, unless we admitted something which, existing by itself, original and independent, outside the chain of infinite contingencies, should support it, and, as the cause of its origin, secure to it at the same time its permanence. Looking at all the things in the world, what greatness shall we attribute to that highest cause? We do not know the whole contents of the world, still less can we measure its magnitude by a comparison with all that is possible. But, as with regard to causality, we cannot do without a last and highest Being, why should we not fix the degree of its perfection beyond everything else that is possible? This we can easily do, though only in the faint outline of an abstract concept, if we represent to ourselves all possible perfections united in it as in one substance. Such a concept would agree with the demand of our reason, which requires parsimony in the number of principles; it would have no contradictions in itself, would be favourable to the extension of the employment of reason in the midst of experience, by guiding it towards order and system, and lastly, would never be decidedly opposed to any experience.
This proof will always deserve to be treated with respect. It is the oldest, the clearest, and most in conformity with human reason. It gives life to the study of nature, deriving its own existence from it, and thus constantly acquiring new vigour.
It reveals aims and intention, where our own observation would not by itself have discovered them, and enlarges our knowledge of nature by leading us towards that peculiar unity the principle of which exists outside nature. This knowledge reacts again on its cause, namely, the transcendental idea, and thus increases the belief in a supreme Author to an irresistible conviction.
It would therefore be not only extremely sad, but utterly vain to attempt to diminish the authority of that proof. Reason, constantly strengthened by the powerful arguments that come to hand by themselves, though they are no doubt empirical only, cannot be discouraged by any doubts of subtle and abstract speculation. Roused from every inquisitive indecision, as from a dream, by one glance at the wonders of nature and the majesty of the cosmos, reason soars from height to height till it reaches the highest, from the conditioned to conditions, till it reaches the supreme and unconditioned Author of all.
But although we have nothing to say against the reasonableness and utility of this line of argument, but wish, on the contrary, to commend and encourage it, we cannot approve of the claims which this proof advances to apodictic certainty, and to an approval on its own merits, requiring no favour, and no help from any other quarter. It cannot injure the good cause, if the dogmatical language of the overweening sophist is toned down to the moderate and modest statements of a faith which does not require unconditioned submission, yet is sufficient to give rest and comfort. I therefore maintain that the physico-theological proof can never establish by itself alone the existence of a Supreme Being, but must always leave it to the ontological proof (to which it serves only as an introduction), to supply its deficiency; so that, after all, it is the ontological proof which contains the only possible argument (supposing always that any speculative proof is possible), and human reason can never do without it.
The principal points of the physico-theological proof are the following. 1st. There are everywhere in the world clear indications of an intentional arrangement carried out with great wisdom, and forming a whole indescribably varied in its contents and infinite in extent.
2ndly. The fitness of this arrangement is entirely foreign to the things existing in the world, and belongs to them contingently only; that is, the nature of different things could never spontaneously, by the combination of so many means, co-operate towards definite aims, if these means had not been selected and arranged on purpose by a rational disposing principle, according to certain fundamental ideas.
3rdly. There exists, therefore, a sublime and wise cause (or many), which must be the cause of the world, not only as a blind and all-powerful nature, by means of unconscious fecundity, but as an intelligence, by freedom.
4thly. The unity of that cause may be inferred with certainty from the unity of the reciprocal relation of the parts of the world, as portions of a skilful edifice, so far as our experience reaches, and beyond it, with plausibility, according to the principles of analogy.
Without wishing to argue, for the sake of argument only, with natural reason, as to its conclusion in inferring from the analogy of certain products of nature with the works of human art, in which man does violence to nature, and forces it not to follow its own aims, but to adapt itself to ours (that is, from the similarity of certain products of nature with houses, ships, and watches), in inferring from this, I say, that a similar causality, namely, understanding and will, must be at the bottom of nature, and in deriving the internal possibility of a freely acting nature (which, it may be, renders all human art and even human reason possible) from another though superhuman art—a kind of reasoning, which probably could not stand the severest test of transcendental criticism; we are willing to admit, nevertheless, that if we have to name such a cause, we cannot do better than to follow the analogy of such products of human design, which are the only ones of which we know completely both cause and effect. There would be no excuse, if reason were to surrender a causality which it knows, and have recourse to obscure and indemonstrable principles of explanation, which it does not know.
According to this argument, the fitness and harmony existing in so many works of nature might prove the contingency of the form, but not of the matter, that is, the substance in the world, because, for the latter purpose, it would be necessary to prove in addition, that the things of the world were in themselves incapable of such order and harmony, according to general laws, unless there existed, even in their substance, the product of a supreme wisdom. For this purpose, very different arguments would be required from those derived from the analogy of human art. The utmost, therefore, that could be established by such a proof would be an architect of the world, always very much hampered by the quality of the material with which he has to work, not a creator, to whose idea everything is subject. This would by no means suffice for the purposed aim of proving an all-sufficient original Being. If we wished to prove the contingency of matter itself, we must have recourse to a transcendental argument, and this is the very thing which was to be avoided.
The inference, therefore, really proceeds from the order and design that can everywhere be observed in the world, as an entirely contingent arrangement, to the existence of a cause, proportionate to it. The concept of that cause must therefore teach us something quite definite about it, and can therefore be no other concept but that of a Being which possesses all might, wisdom, etc., in one word, all perfection of an all-sufficient Being. The predicates of a very great, of an astounding, of an immeasurable might and virtue give us no definite concept, and never tell us really what the thing is by itself. They are only relative representations of the magnitude of an object, which the observer (of the world) compares with himself and his own power of comprehension, and which would be equally grand, whether we magnify the object, or reduce the observing subject to smaller proportions in reference to it. Where we are concerned with the magnitude (of the perfect
ion) of a thing in general, there exists no definite concept, except that which comprehends all possible perfection, and only the all (omnitudo) of reality is thoroughly determined in the concept.
Now I hope that no one would dare to comprehend the relation of that part of the world which he has observed (in its extent as well as in its contents) to omnipotence, the relation of the order of the world to the highest wisdom, and the relation of the unity of the world to the absolute unity of its author, etc. Physico-theology, therefore, can never give a definite concept of the highest cause of the world, and is insufficient, therefore, as a principle of theology, which is itself to form the basis of religion.
The step leading to absolute totality is entirely impossible on the empirical road. Nevertheless, that step is taken in the physico-theological proof. How then has this broad abyss been bridged over?
The fact is that, after having reached the stage of admiration of the greatness, the wisdom, the power, etc. of the Author of the world, and seeing no further advance possible, one suddenly leaves the argument carried on by empirical proofs, and lays hold of that contingency which, from the very first, was inferred from the order and design of the world. The next step from that contingency leads, by means of transcendental concepts only, to the existence of something absolutely necessary, and another step from the absolute necessity of the first cause to its completely determined or determining concept, namely, that of an all-embracing reality. Thus we see that the physico-theological proof, baffled in its own undertaking, takes suddenly refuge in the cosmological proof, and as this is only the ontological proof in disguise, it really carries out its original intention by means of pure reason only; though it so strongly disclaimed in the beginning all connection with it, and professed to base everything on clear proofs from experience.
Critique of Pure Reason Page 49