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Some key arguments from Meditations III-V
I. THIRD MEDITATION: The existence of God
A. Cosmological proof of the Existence of God In the 3rd Meditation, Descartes attempts to prove that God (i) exists, (ii) is the cause of the essence of the meditator (i.e. the author of his nature as a thinking thing), and (iii) the cause of the meditator’s existence (both as creator and conserver, i.e. the cause that keeps him in existence from one moment to the next). The proof that God exists premises that each of us understand the following clear and distinct idea of God: Definition. “By ‘God’ I mean the very being the idea of whom is within me, that is, the possessor of all the perfections which I cannot grasp, but can somehow reach in my thought, who is subject to no defects whatsoever.” Without entering into the details of the proof, Descartes’s objective is to demonstrate that this idea can have no other cause than God. Some of the main features of the proof are the following: —The proof is cosmological because it is an inference from a given effect (here the idea of God) to the existence of God as the cause of that effect, and proceeds by showing that every other possible cause is inadequate. It contrasts with the ontological proof of the Fifth Meditation in which Descartes argues from the essence of God, as a being possessed of all perfections, to the existence of God (on the ground that existence too must be accounted a perfection, i.e. inexistent beings are, by virtue of their lack of existence, less perfect than existing ones). —The aim of Descartes’s proofs are to demonstrate the irrationality of both atheism and agnosticism by showing that reason operating alone (independently of all the commitments of faith) requires us to affirm the existence of God with the very same certainty of which it revealed itself capable when affirming our own existence as thinking beings in the Second Meditation. —Accordingly, the proof presupposes nothing but (i) the meditator’s own existence as a thinking substance and (ii) the existence (as modifications of the meditator’s mind) of the ideas the meditator thinks. On the basis of these two certainties, together with the certainty of such eternal truths as that everything that exists must have a cause of its existence, Descartes reasoned that the existence in us of the idea of God is impossible through any other cause than God (to do so, he first excluded the possibility that any being less than God could be its cause, and then proved that the meditator is such a being, i.e. that the meditator cannot, unbeknownst to him- or herself, be God). —If one accepts that Descartes’s reasoning in the proof is both valid (= the conclusion is known to be implied by the premises) and sound (= the premises are all known to be true), it enables one to know that God exists with the same skepticism-defeating certainty with which one knows that the idea of God exists as a present modification of one’s thinking being.
B. Eliminating the Evil Deceiver doubt of the First Meditation. In the course of his proof for the existence of God, Descartes needed to show that the idea of God is present in all our intellects innately (even if we are not explicitly aware of its
presence there owing to the confusion and disorderliness of our minds). He did so by arguing (i) that we could not understand the words of the definition if the idea were not already in us wordlessly; and (ii) that no amount of reflection on the ideas of finite beings we gain through the senses, imagination, or intellect (whether of ourselves as thinking beings or of corporeal substances such as the piece of wax) could yield the idea of God either. Given that the idea of God is innate to our intellects, the only way it could have gotten there is if the only possible cause of that idea – the supreme being itself – had caused it to be there. Since this would be impossible unless God were likewise the cause of our intellects as a whole, it follows that our nature as thinking beings capable of conceiving a supreme being derives directly from God (i.e. God is our essential cause, not just the cause of our existence ). If God is the cause of our nature as thinking beings, it follows that this nature can only be defective in the manner postulated in the First Meditation (viz. be essentially inclined to error rather than to truth) if it were possible for God to be a deceiver. Can God, as defined above, be a deceiver? Descartes’s answer is no: “it is manifest by the natural light that all fraud and deception depend on some defect.”
Proof that God is not a deceiver:
- From the supreme being only being may flow (nonbeing – nothingness – neither needs nor can have a cause).
- As finite and limited, all creatures (created beings like ourselves) consist of nonbeing as well as being.
- Only the being of creatures can derive from God, not their nonbeing.
- Truth is the being of knowledge, falsity and ignorance its nonbeing.
- Falsity can never flow from God, never be caused by God.
- As the cause both of my essence and my existence, God cannot be the cause of my errors.
- Therefore, God is not the cause of my error and ignorance; and by similar reasoning, we may clearly and distinctly perceive that no being is ever deceived by God.
II. FOURTH MEDITATION: Truth and falsity
A. Definitions of ‘clear’ and ‘distinct’ perception (from Descartes’s Principles of Philosophy ): There are very many people who in their entire lives never perceive anything with sufficient accuracy to enable them to make a judgment about it with certainty. A perception that can serve as the basis for a certain and indubitable judgment needs to be not merely clear but also distinct. I call a perception ‘clear’ when it is present and accessible to the attentive mind – just as we say that we see something clearly when it is present to the eye’s gaze and stimulates it with a sufficient degree of strength and accessibility. I call a perception ‘distinct’ if, as well as being clear, it is so sharply separated from all other perceptions that it contains within itself only what is clear. (§45) In our childhood the mind was so immersed in the body that although there was much that it perceived clearly, it never perceived anything distinctly. But in spite of this the mind made judgments about many things, and this is the origin of the many preconceived opinions which most of us never subsequently abandon. (§47)
condemns me to err. Consequently, I can never shift the responsibility for the error and evil I commit to the supreme being that created me. The plan of the Meditations thus becomes clear: the skepticism of the First Meditation is aimed at instilling in us a habit of suspending judgment where clear and distinct perception is lacking; the Second Meditation shows us what genuine knowledge is (= clear and distinct perception) and where such knowledge begins (viz. self-knowledge); and the subsequent Meditations show how we can pursue and secure new knowledge on the basis of the “Archimedean point” of self-knowledge (by exerting our will to affirm all and only that which we are able to perceive clearly and distinctly).
Descartes’s proof of the truth-criterion: everything I clearly and distinctly perceive is true
- I lack any faculty whereby to discover anything I clearly and distinctly perceive to be mistaken.
- God would be a deceiver if, lacking such a faculty, my nature was in fact so defective that I tended inexorably to error and illusion.
- By the conclusion of the proof that God is not a deceiver, it follows that it is impossible that I am by nature prone to error (i.e. the metaphysical doubt grounded on the malicious demon hypothesis is refuted).
- Since the only ground I had for doubting things I clearly and distinct perceive (i.e. intuitively and demonstratively apprehended propositions of logic, mathematics, and metaphysics) is now removed, it follows that everything I clearly and distinctly perceive is true.
V. FIFTH MEDITATION: The essence of material things, and the existence of God considered a second time
A. The ideas of corporeal things are not chimerical Thesis: Whereas the act of thinking of corporeal things is subject to my will (I can attend to them or not as I please), certain of the contents of our thought of them (i.e. their nature, essence ) are not: “they are not my invention but have their own true and immutable natures .” Proof: The ability to demonstrate mathematically that certain determinations hold of necessity with reference to general ideas of spatial extension, e.g. the properties of a triangle, proves that I cannot have invented these ideas. For if these ideas were my inventions, it would be in my power to add or subtract determinations from them at will, e.g., I could, at a whim, change things so that the sum of the angles of a triangle equals three right angles instead of two. However, once mathematical methods enable me to perceive clearly and distinctly that certain properties belong to ideas of extension of necessity (e.g. the necessary equality between the sum of the angles of any triangle and two right angles), I clearly and distinctly perceive that it is not in my power to take away or alter this determination at will. For the same reason, I also clearly and distinctly perceive that I could not have put it in there in the first place; for whatever is in the power of my will to add to an idea must also be in my power to take away from it. Thus, “whether I want [these determinations in the idea] or not, even if I never thought of them at all when I previously imagined the triangle,” they necessarily belong to it; and this, according to Descartes, proves beyond any possibility of doubt that these properties “cannot have been invented by me,” but
instead pertain to the nature of triangles as such (“a determinate nature, or essence , or form of the triangle which is immutable and eternal , and not invented by me or dependent on my mind”). We thus can know with complete certainty that the clear and distinct idea we have of a triangle is not chimerical but instead corresponds to a positive essence (genuine nature), and so to a possible existence. (The purpose of the Sixth Meditation is to prove the actual existence of that which the Fifth Meditation proved to be possibly existent.) NB. For Descartes, corporeal reality is res extensa (extended being). This means that there is no real distinction between body and space, i.e. the notion of empty space is a contradiction (hence not a genuine idea at all): “ There is no real difference between space and corporeal substance. It is easy for us to recognize that the extension constituting the nature of a body is exactly the same as that constituting the nature of a space. There is no more difference between them than there is between the nature of a genus or species and the nature of an individual. Suppose we attend to the idea we have of some body, for example a stone, and leave out everything we know to be non-essential to the nature of body: we will first of all exclude hardness, since if the stone is melted or pulverized it will lose its hardness without thereby ceasing to be a body; next we will exclude color, since we have often seen stones so transparent as to lack color; next we will exclude heaviness, since although fire is extremely light it is still thought of as being corporeal; and finally we will exclude cold and heat and all other such qualities, either because they are not thought of as being in the stone, or because if they change, the stone is not on that account reckoned to have lost its bodily nature. After all this, we will see that nothing remains in the idea of the stone except that it is something extended in length, breadth and depth. Yet this is just what is comprised in the idea of a space – not merely a space which is full of bodies, but even a space which is called ‘empty’ ( vacuum ).” ( Principles II,11) Gloss. To understand this, you must not confuse the insensibility of certain kinds of matter with an idea of empty space. E.g. to see only blackness in a region of space through a telescope is not to see empty space; it simply means that our eyes (and other detectors) are insensitive to whatever corporeal being may be present in that region. Indeed, empty space is, by definition, not an object of a possible sense perception: perception requires that there be something capable of affecting our sense organs; since such affection is only possible by means of corporeal causes acting on our (equally corporeal) organs of sensation, it follows that empty space can have no causal interaction with our senses, or, indeed, with any body whatsoever. Accordingly, the possibility of empty space cannot be established empirically but only by rational (purely conceptual) considerations alone, if at all. In the text cited, Descartes makes the conceptual point that it is impossible to abstract out everything essential to body without also abstracting everything that is essential to space. The implication is that there is no conception we can form to give the words ‘empty space’ a meaning (e.g. the very question itself as to whether a vacuum exists, or is possible, is empty, devoid of meaning, nonsensical).
B. Descartes’s ontological proof for the existence of God (1) I find in me the idea of God, a supremely perfect being. (2) I perceive in this idea that actual and eternal existence belongs to the nature of God of necessity. (3) Since actual, eternal existence belongs to the idea of God of necessity, it is impossible for me to think the nature of God without also thinking that actual existence pertains to God.
