All this is set forth very plausibly, but it is still indeterminate, formal, and shallow; we only have the assertion made to us that this is so. Descartes’ method is the method of the clear understanding merely. Certainty with him takes the first place; from it no content is deduced of necessity, no content generally, and still less its objectivity as distinguished from the inward subjectivity of the ‘I.’ At one time we have the opposition of subjective knowledge and actuality, and at another their inseparable union. In the first case the necessity of mediating them enters in, and the truth of God is asserted to be this mediating power. It consists in this, that His Notion contains reality immediately in itself. The proof of this unity then rests solely upon the fact of its being said that we find within us the idea of complete perfection; thus this conception here appears simply as one found ready to hand. With this is compared the mere conception of God which contains no existence within it, and it is found that without existence it would be imperfect. This unity of God Himself, of His Idea, with His existence, is undoubtedly the Truth; in this we find the ground for holding as true what is for us just as certain as the truth of ourselves. As Descartes proceeds further we thus find that in reality everything has truth for him only in so far as it is really an object of thought, a universal. This truth of God has been, as we shall see, expressed even more clearly and in a more concise way by a disciple of Descartes, if one may venture to call him so—I mean Malebranche (who might really be dealt with here),[177] in his Recherche de la vérité.
The first of the fundamental determinations of the Cartesian metaphysics is from the certainty of oneself to arrive at the truth, to recognize Being in the Notion of thought. But because in the thought “I think,” I am an individual, thought comes before my mind as subjective; Being is hence not demonstrated in the Notion of thought itself, for what advance has been made is merely in the direction of separation generally. In the second place the negative of Being likewise comes before self-consciousness, and this negative, united with the positive I, is so to speak implicitly united in a third, in God. God, who before this was a non-contradictory potentiality, now takes objective form to self-consciousness, He is all reality in so far as it is positive, i.e. as it is Being, unity of thought and Being, the highest perfection of existence; it is just in the negative, in the Notion of this, in its being an object of thought, that Being is contained. An objection to this identity is now old—Kant urged it likewise—that from the Notion of the most perfect existence more does not follow than that in thought existence here and now and the most perfect essence are conjoined, but not outside of thought. But the very Notion of present existence is this negative of self-consciousness, not out of thought,—but the thought of the ‘out of thought.’
2. Descartes accepts Being in the entirely positive sense, and has not the conception of its being the negative of self-consciousness: but simple Being, set forth as the negative of self-consciousness, is extension. Descartes thus separates extension from God, remains constant to this separation, unites the universe, matter, with God in such a way as to make Him its creator and first cause: and he has the true perception that conservation is a continuous creation, in so far as creation as activity is asserted to be separated. Descartes does not, however, trace extension in a true method back to thought; matter, extended substances, stand over against the thinking substances which are simple; in as far as the universe is created by God, it could not be as perfect as its cause. As a matter of fact the effect is less perfect than the cause, since it is that which is posited, if we are to remain at the conception of cause pertaining to the understanding. Hence according to Descartes extension is the less perfect. But as imperfect the extended substances cannot exist and subsist through themselves or their Notion; they thus require every moment the assistance of God for their maintenance, and without this they would in a moment sink back into nothing. Preservation is, however, unceasing reproduction.[178]
Descartes now proceeds to further particulars, and expresses himself as follows: “We consider what comes under consciousness either as things or their qualities, or as eternal truths which have no existence outside our thought”—which do not belong to this or that time, to this or that place. He calls those last something inborn within us, something not made by us or merely felt,[179] but the eternal Notion of mind itself and the eternal determinations of its freedom, of itself as itself. From this point the conception that ideas are inborn (innatæ ideæ) hence proceeds; this is the question over which Locke and Leibnitz dispute. The expression “eternal truths” is current even in these modern times, and it signifies the universal determinations and relations which exist entirely on their own account. The word ‘inborn’ is however a clumsy and stupid expression, because the conception of physical birth thereby indicated, does not apply to mind. To Descartes inborn ideas are not universal, as they are to Plato and his successors, but that which has evidence, immediate certainty, an immediate multiplicity founded in thought itself—manifold conceptions in the form of a Being, resembling what Cicero calls natural feelings implanted in the heart. We would rather say that such is implied in the nature and essence of our mind and spirit. Mind is active and conducts itself in its activity in a determinate manner; but this activity has no other ground than its freedom. Yet if this is the case more is required than merely to say so; it must be deduced as a necessary product of our mind. We have such ideas, for instance, in the logical laws: “From nothing comes nothing,” “A thing cannot both be and not be,”[180] as also in moral principles. These are facts of consciousness which Descartes however soon passes from again; they are only present in thought as subjective, and he has thus not yet inquired respecting their content.
As regards things, on which Descartes now directs his attention, the other side to these eternal verities, the universal determinations of things are substance, permanence, order, &c.[181] He then gives definitions of these thoughts, just as Aristotle draws up a list of the categories. But although Descartes laid it down formerly as essential that no hypotheses must be made, yet now he takes the conceptions, and passes on to them as something found within our consciousness. He defines substance thus: “By substance I understand none other than a thing (rem) which requires no other something for existence; and there is only one thing, namely God, which can be regarded as such a substance requiring no other thing.” This is what Spinoza says; we may say that it is likewise the true definition, the unity of Notion and reality: “All other” (things) “can only exist by means of a concurrence (concursus) of God”; what we still call substance outside of God thus does not exist for itself, does not have its existence in the Notion itself. That is then called the system of assistance (systema assistentiæ) which is, however, transcendental. God is the absolute uniter of Notion and actuality; other things, finite things which have a limit and stand in dependence, require something else. “Hence if we likewise call other things substances, this expression is not applicable both to them and to God univoce, as is said in the schools; that is to say no definite significance can be given to this word which would equally apply both to God and to the creatures.”[182]
“But I do not recognize more than two sorts of things; the one is that of thinking things, and the other that of things which relate to what is extended.” Thought, the Notion, the spiritual, the self-conscious, is what is at home with itself, and its opposite is contained in what is extended, spatial, separated, not at home with itself nor free. This is the real distinction (distinctio realis) of substances: “The one substance can be clearly and definitely comprehended without the other. But the corporeal and the thinking and creating substance can be comprehended under this common notion, for the reason that they are things which require God’s support alone in order to exist.” They are universal; other finite things require other things as conditions essential to their existence. But extended substance, the kingdom of nature, and spiritual substance, do not require one another.[183] They may be called substances, because each of them constitutes an entire range or sphere, an independent totality. But because, Spinoza concluded, each side, the kingdom of thought as well as nature, is one complete system within itself, they are likewise in themselves, that is absolutely, identical as God, the absolute substance; for thinking spirit this implicit is thus God, or their differences are ideal.
Descartes proceeds from the Notion of God to what is created, to thought and extension, and from this to the particular. “Now substances have several attributes without which they cannot be thought”—that signifies their determinateness—“but each has something peculiar to itself which constitutes its nature and essence”—a simple universal determinateness—“and to which the others all relate. Thus thought constitutes the absolute attribute of mind,” thought is its quality; “extension is” the essential determination of corporeality, and this alone is “the true nature of body. What remains are merely secondary qualities, modes, like figure and movement in what is extended, imagination, feeling and will in thinking; they may be taken away or thought away. God is the uncreated, thinking substance.”[184]
Descartes here passes to what is individual, and because he follows up extension he arrives at matter, rest, movement. One of Descartes’ main points is that matter, extension, corporeality, are quite the same thing for thought; according to him the nature of body is fulfilled in its extension, and this should be accepted as the only essential fact respecting the corporeal world. We say that body offers resistance, has smell, taste, colour, transparency, hardness, &c., since without these we can have no body. All these further determinations respecting what is extended, such as size, rest, movement, and inertia, are, however, merely sensuous, and this Descartes showed, as it had long before this been shown by the Sceptics. Undoubtedly that is the abstract Notion or pure essence, but to body or to pure existence, there likewise of necessity pertains negativity or diversity. By means of the following illustration Descartes showed that with the exception of extension, all corporeal determinations may be annihilated, and that none can be absolutely predicated. We draw conclusions respecting the solidity and hardness of matter from the resistance which a body offers to our disturbance, and by means of which it seeks to hold its place. Now if we admit that matter as we touch it always gives way to us like space, we should have no reason for ascribing to it solidity. Smell, colour, taste, are in the same way sensuous qualities merely; but what we clearly perceive is alone true. If a body is ground into small parts, it gives way, and yet it does not lose its nature; resistance is thus not essential.[185] This not-being-for-itself is however a quantitatively slighter resistance only; the resistance always remains. But Descartes desires only to think; now he does not think resistance, colour, &c., but apprehends them by the senses only. Hence he says that all this must be led back to extension as being special modifications of the same. It is undoubtedly to the credit of Descartes that he only accepts as true what is thought; but the abrogation of these sensuous qualities simply represents the negative movement of thought: the essence of body is conditioned through this thought, that is, it is not true essence.
Descartes now makes his way from the Notion of extension to the laws of motion, as the universal knowledge of the corporeal in its implicitude; he shows (α) that there is no vacuum, for that would be an extension without bodily substance, i.e. a body without body; (β) that there are no atoms (no indivisible independent existence), for the same reason, viz., because the essence of body is extension. (γ) He further shows that a body is set in motion by something outside of it, but of itself it continues in a condition of rest, and likewise it must, when in a condition of movement, be brought to rest by another outside of it—this is the property of inertia.[186] These are unmeaning propositions, for an abstraction is involved for instance in asserting simple rest and movement in their opposition.