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Trademark argument

Argument for the existence of God

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Through Argument

In the Meditations Descartes provides two arguments for the existence of God. In Meditation V he presents a version of the ontological argument which attempts to deduce the existence of God from the nature of God; in Meditation III he presents an argument for the existence of God from one of the effects of God's activity. Descartes cannot start with the existence of the world or with some feature of the world for, at this stage of his argument, he has not established that the world exists. Instead, he starts with the fact that he has an idea of God and concludes "that the mere fact that I exist and have within me an idea of a most perfect being, that is, God, provides a very clear proof that God indeed exists." He says, "it is no surprise that God, in creating me, should have placed this idea in me to be, as it were, the mark of the craftsman stamped on his work."

Underlying assumptions

To understand Descartes' argument it is necessary to understand some of the metaphysical assumptions that Descartes is using.

Degrees of reality

Descartes says,

Undoubtedly, the ideas which represent substances to me amount to something more and, so to speak, contain within themselves more objective reality than the ideas which merely represent modes or accidents. Again, the idea that gives me my understanding of a supreme God...certainly has in it more objective reality than the ideas that represent finite substances. Now it is manifest by the natural light that there must be at least as much reality in the efficient and total cause as in the effect of that cause. For where, I ask, could the effect get its reality from, if not from the cause? And how could the cause give it to the effect unless it possessed it? It follows from this both that something cannot arise from nothing, and also that what is more perfect—that is, contains in itself more reality—cannot arise from what is less perfect.

Descartes goes on to describe this as 'transparently true'. Commenting on this passage Williams says, "This is a piece of scholastic metaphysics, and it is one of the most striking indications of the historical gap that exists between Descartes' thought and our own, despite the modern reality of much else that he writes, that he can unblinkingly accept this unintuitive and barely comprehensible principle as self-evident in the light of reason."

In his own time, it was challenged by Hobbes who in the Objections says, "Moreover, M. Descartes should consider afresh what 'more reality' means. Does reality admit of more and less? Or does he think one thing can be more of a thing than another? If so, he should consider how this can be explained to us with that degree of clarity that every demonstration calls for, and which he himself has employed elsewhere."

To this Descartes replies:

"I have ... made it quite clear how reality admits of more and less. A substance is more of a thing than a mode; if there are real qualities or incomplete substances, they are things to a greater extent than modes, but to a lesser extent than complete substances; and, finally, if there is an infinite and independent substance, it is more of a thing than a finite and dependent substance. All this is completely self-evident."

To understand Descartes' Trademark Argument it is not necessary to fully understand the underlying Aristotelian metaphysics but it is necessary to know that

  • an infinite substance has the most reality and more reality than
  • a finite substance, which in turn has more reality than
  • a mode.

A substance is something that exists independently. The only thing that truly exists independently is an infinite substance for it does not rely on anything else for its existence. In this context 'infinite substance' means 'God'. A finite substance can exist independently other than its reliance on an infinite substance. 'Substance' does not imply 'physical substance'—for Descartes the body is one substance but the mind is also a substance.

A 'mode' is "a way or manner in which something occurs or is experienced, expressed, or done." In this scheme, a substance (e.g. a mind) will have an attribute (thought) and the mode might be willing or having an idea.

The degree of reality is related to the way in which something is dependent—"Modes are logically dependent on substance; they 'inhere in it as subject.'... Created substances are not logically, but causally, dependent on God. They do not inhere in God as subject, but are effects of God as creator."

Formal reality and Objective reality

Descartes says,

The nature of an idea is such that of itself it requires no formal reality except what it derives from my thought, of which it is a mode. But in order for a given idea to contain such and such objective reality, it must surely derive it from some cause which contains at least as much formal reality as there is objective reality in the idea.

'Formal reality' is roughly what we mean by 'actually existing.' 'Objective reality' does not mean objective as opposed to subjective but is more like the object of one's thoughts irrespective of whether or not it actually exists. Cottingham says that 'objective reality' is the 'representational content of an idea'. Hatfield says "think of an "object" of desire—a championship for your favorite sports team, say. It may not now exist, and it need never have existed. In Descartes' terminology, what has "objective reality" is something contained in the subject's mental state and so may even be called "subjective" in present-day terms."

Crucial to Descartes argument is the way in which the levels of objective reality are determined. The level of objective reality is determined by the formal reality of what is being represented or thought about. So every idea I have has the lowest level of formal reality, for every idea is a mode, but the idea of an infinite substance has more objective reality than the idea of a finite substance. Kenny notes, "we sometimes use the word 'reality' to distinguish fact from fiction: on this view, the idea of a lion would have more objective reality than the idea of a unicorn since lions exist and unicorns do not. But this is not what Descartes means." In this instance the idea of a lion and the idea of a unicorn would have the same objective reality because a lion and a unicorn (if it existed) would both be finite substances.

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