He outlines some of the objections to the Discourse and asserts that his critics generally ignored his chains of logic and only attacked his conclusions. He pledges to return to the two criticisms he finds worth considering. He asks his readers to approach the rest of the book with an unbiased mind. The first meditation reiterates material from the Discourse. Responding to an objection to his critique of the senses, Descartes agrees that he would seem a madman if he argued he was not sure that he possessed a body.
But he also points out that in his dreams he experiences a reality as convincing as his waking reality. He can find no sure way to distinguish between waking life and sleep. He then goes on to argue that if we dream of hands, feet, eyes, and bodies, then they must actually exist. When we dream, he continues, we use information we gathered from reality. Even if particular complex objects do not exist, at least the basic colors and shapes that compose them exist.
In the same way, we can say the physical sciences are uncertain because they study composites. Arithmetic and geometry study simple objects shapes, angles, numbers and are therefore trustworthy. He trusts his perceptions of self-evident truths such as simple shapes and numbers because he believes in an all-powerful God that created these things. Descartes admits that he cannot be sure that God is not playing some sort of trick on him.
Therefore, Descartes cannot be certain of any proposition that is not Demon-proof. Descartes needs to be certain of some things other than I exist before he can prove the existence of God.
But in order to have this certainty, he must already know that God exists. He is caught in a vicious circle. Some say there is none. Maybe they are right, but we will consider a different line. So, a proof of the existence of God has not been ruled out. The most famous of these was given by Saint Anselm of Canterbury The reality of any effect must come from its cause.
Therefore, from 1 there must be at least as much reality in the cause of any thing as in the effect. Example: A stone cannot exist unless it was caused to exist by something that contains all the reality of a stone in this case, everything that is in the stone. So, for example, my idea of a stone must have originated in something that has at least as much reality as an actual stone. I have an idea of God, which is the idea of an infinite, supremely intelligent, supremely powerful, and all-around perfect being.
Therefore, from 3 , my idea of God must have originated in something that has at least as much reality as an actually existing God. I am finite and imperfect. This is proved by the very fact that my knowledge is being increased. Therefore, from 3, 4 and 6 I do not possess as much reality as an existing God, and the idea of God cannot have originated in me. Only an existing God could possess enough reality to have originated my idea of God. Therefore, from God--an infinite, supremely intelligent, supremely powerful, and all-around perfect being not identical to myself--exists in reality.
So Descartes requires something weaker: the cause of the idea must be at least as real as the thing itself were it to exist. Thus, my idea of Santa Claus need not be caused by Santa Claus himself; it may be caused by other things—men with white beards, the north pole, etc. At any rate, according to Descartes, God is at such a level of reality being infinite and totally perfect that nothing could cause the idea of god except God himself.
Arguably, the concept of infinity could have originated in something else that was infinite say, an infinite sequence of numbers. The concept of perfection could have originated in something else that was perfect say, a perfect rose. Then, the mind could simply put these concepts together to form the concept of God, much in the way that it could form the concept of a unicorn by putting together the concept of a horse and the concept of a horn. This is an objection to premise 8. Descartes considers this objection:.
But this reply is of no help. Unity and inseparability are just other concepts that could have originated in other, non-Godly things. The concept of inseparability might come from the logical notion of entailment.
These could have been put together with the concepts of infinity and perfection to form the concept of God. So far, he knows himself only as a thinking thing. He takes himself to have proven only that he and God exist.
From here, he wants to show that extended things such as his own body, as well as other physical objects exist as well. Existence is derived immediately from the clear and distinct idea of a supremely perfect being.
The main statement of the argument appears in the Fifth Meditation. Descartes repeats the ontological argument in a few other central texts including the Principles of Philosophy. He also defends it in the First, Second, and Fifth Replies against scathing objections by some of the leading intellectuals of his day.
Descartes was not the first philosopher to formulate an ontological argument. An earlier version of the argument had been vigorously defended by St. Thomas Aquinas. Descartes often compares the ontological argument to a geometric demonstration, arguing that necessary existence cannot be excluded from idea of God anymore than the fact that its angles equal two right angles, for example, can be excluded from the idea of a triangle.
According to this tradition, one can determine what something is i. Indeed, it reads more like the report of an intuition than a formal proof. Descartes underscores the simplicity of his demonstration by comparing it to the way we ordinarily establish very basic truths in arithmetic and geometry, such as that the number two is even or that the sum of the angles of a triangle is equal to the sum of two right angles. We intuit such truths directly by inspecting our clear and distinct ideas of the number two and of a triangle.
As Descartes writes in the Fifth Meditation:. Descartes does not conceive of the ontological argument on the model of an Euclidean or axiomatic proof, in which theorems are derived from epistemically prior axioms and definitions. On the contrary, he is drawing our attention to another method of establishing truths that informs our ordinary practices and is non-discursive. This method employs intuition or, what is the same for Descartes, clear and distinct perception.
It consists in unveiling the contents of our clear and distinct ideas. The basis for this method is the rule for truth, which was previously established in the Fourth Meditation.
According to the version of this rule invoked in the Fifth Meditation, whatever I clearly and distinctly perceive to be contained in the idea of something is true of that thing. So if I clearly and distinctly perceive that necessary existence pertains to the idea of a supremely perfect being, then such a being truly exists. He never forgets that he is writing for a seventeenth-century audience, steeped in scholastic logic, that would have expected to be engaged at the level of the Aristotelian syllogism.
Descartes satisfies such expectations, presenting not one but at least two separate versions of the ontological argument. These proofs, however, are stunningly brief and betray his true intentions. When presenting this version of the argument in the First Replies, Descartes sets aside this first premise and focuses our attention on the second.
In so doing, he is indicating the relative unimportance of the proof itself. Descartes sometimes uses traditional arguments as heuristic devices, not merely to appease a scholastically trained audience but to help induce clear and distinct perceptions. This is evident for example in the version of the ontological argument standardly associated with his name:.
While this set of sentences has the surface structure of a formal argument, its persuasive force lies at a different level. A meditator who is having trouble perceiving that necessary existence is contained in the idea of a supreme perfect being can attain this perception indirectly by first recognizing that this idea includes every perfection. Indeed, the idea of a supremely perfect being just is the idea of a being having all perfections.
To attempt to exclude any or all perfections from the idea of a supremely being, Descartes observes, involves one in a contradiction and is akin to conceiving a mountain without a valley or, better, an up-slope without a down-slope. Having formed this perception, one need only intuit that necessary existence is itself a perfection.
It will then be clear that necessary existence is one of the attributes included in the idea of a supremely perfect being. While such considerations might suffice to induce the requisite clear and distinct perception in the meditator, Descartes is aiming a deeper point, namely that there is a conceptual link between necessary existence and each of the other divine perfections. It is important to recall that in the Third Meditation, in the midst of the causal argument for the existence of God, the meditator already discovered many of these perfections — omnipotence, omniscience, immutability, eternality, simplicity, etc.
To illustrate this point Descartes appeals to divine omnipotence. He thinks that we cannot conceive an omnipotent being except as existing. Since such a being does not depend on anything else for its existence, he has neither a beginning nor an end, but is eternal.
Returning to the discussion in the First Replies, one can see how omnipotence is linked conceptually to necessary existence in this traditional sense. An omnipotent or all-powerful being does not depend ontologically on anything for if it did then it would not be omnipotent. It exists by its own power:. Some readers have thought that Descartes offers yet a third version of the ontological argument in this passage Wilson, , —76 , but whether or not that was his intention is unimportant, since his primary aim, as indicated in the last line, is to enable his meditator to intuit that necessary existence is included in the idea of God.
Since there is a conceptual link between the divine attributes, a clear and distinct perception of one provides a cognitive route to any of the others. The formal versions of the argument are merely heuristic devices, to be jettisoned once one has attained the requisite intuition of a supremely perfect being.
Descartes stresses this point explicitly in the Fifth Meditation, immediately after presenting the two versions of the argument considered above:. Here Descartes develops his earlier analogy between the so-called ontological argument and a geometric demonstration. But other meditators, whose minds are confused and mired in sensory images, must work much harder, and might even require a proof to attain the requisite clear and distinct perception.
Some commentators have thought that Descartes is committed to a species of Platonic realism. According to this view, some objects that fall short of actual existence nevertheless subsist as abstract, logical entities outside the mind and beyond the physical world Kenny, ; Wilson, Another commentator places Cartesian essences in God Schmaltz , while two recent revisionist interpretations Chappell, ; Nolan, read Descartes as a conceptualist who takes essences to be ideas in human minds.
In claiming that necessary existence cannot be excluded from the essence of God, Descartes is drawing on the traditional medieval distinction between essence and existence. According to this distinction, one can say what something is i. So, for example, one can define what a horse is — enumerating all of its essential properties — before knowing whether there are any horses in the world. The only exception to this distinction was thought to be God himself, whose essence just is to exist.
It is easy to see how this traditional distinction could be exploited by a defender of the ontological argument. Existence is included in the essence of a supremely perfect being, but not in the essence of any finite thing. Thus it follows solely from the essence of the former that such a being actually exists.
At times, Descartes appears to support this interpretation of the ontological argument. Understanding this view requires a more careful investigation of the distinction between essence and existence as it appears in medieval sources. The distinction between essence and existence can be traced back as far as Boethius in the fifth century.
It was later developed by Islamic thinkers such as Avicenna. But the issue did not become a major philosophical problem until it was taken up by Aquinas in the thirteenth century. Like many scholastic philosophers, Aquinas believed that God is perfectly simple and that created beings, in contrast, have a composite character that accounts for their finitude and imperfection.
Earthly creatures are composites of matter and form the doctrine of hylomorphism , but since purely spiritual beings are immaterial, Aquinas located their composite character in the distinction between essence and existence. The primary interest of his theory for our purposes, however, is that it led to a lively debate among his successors both as to how to interpret the master and about the true nature of the relation between essence and existence in created things.
This debate produced three main positions:. Proponents of the first view conceived the distinction between essence and existence as obtaining between two separate things. The theory of real distinction was also considered objectionable for philosophical reasons.
On the theory of real distinction, this view leads to an infinite regress. If an essence becomes actual only in virtue of something else — viz. Wippel, , f. In response to these difficulties some scholastic philosophers developed a position at the polar extreme from the theory of real distinction. As the term suggests, this theory held that essence and existence of a creature are identical in reality and distinguished only within our thought by means of reason. Needless to say, proponents of this theory were forced to distinguish purely spiritual entities from God on grounds other than real composition.
Giving up the doctrine of real composition seemed too much for another group of thinkers who were also critical of the theory of real distinction. Articulating this theory in an important passage in the Principles of Philosophy , Descartes claims that there is merely a distinction of reason between a substance and any one of its attributes or between any two attributes of a single substance , AT 8A; CSM Since thought and extension constitute the essence of mind and body, respectively, a mind is merely rationally distinct from its thinking and a body is merely rationally distinct from its extension , AT 8A; CSM But Descartes insists that a rational distinction also obtains between any two attributes of a substance.
Since existence qualifies as an attribute in this technical sense, the essence and existence of a substance are also distinct merely by reason , AT 8A; CSM Descartes reaffirms this conclusion in a letter intended to elucidate his account of the relation between essence and existence:. Indications are given here as to how a rational distinction is produced in our thought. Descartes explains that we regard a single thing in different abstract ways. Case in point, we can regard a thing as existing, or we can abstract from its existence and attend to its other aspects.
In so doing, we have distinguished the existence of a substance from its essence within our thought. Like scholastic proponents of the theory of rational distinction, however, Descartes is keen to emphasize that this distinction is purely conceptual. In reality they are identical. He extends the theory of rational distinction from created substances to God.
In general, the essence and the existence of a substance are merely rationally distinct, and hence identical in reality. One of the most important objections to the argument is that if it were valid, one could proliferate such arguments for all sorts of things, including beings whose existence is merely contingent.
By supposing that there is merely a rational distinction between essence and existence abroad in all things, Descartes seems to confirm this objection. In general, a substance is to be identified with its existence, whether it is God or a finite created thing. The problem with this objection, in this instance, is that it assumes that Descartes locates the difference between God and creatures in the relation each of these things bears to its existence.
This is not the case.
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