Meditation III: Overall Summary

This meditation begins with a summary of Descartes's conclusions so far. However, he finds that he cannot achieve a firm basis for certainty without first proving whether or not God exists, and if so, whether or not God is a deceiver.

To do this Descartes concentrates on where thoughts come from, classifying them according to whether:

• they originate from outside himself (adventitious ideas),
• are created by himself (factitious ideas),
• or that he is born with them (innate ideas).

The purpose of this is, ultimately, to prove that the idea of God is present in his mind as an innate idea.

Finally, having proved this, Descartes uses what has come to be called the trademark argument, attempting to show that the presence of the idea of God in his mind is equivalent to the trademark (or signature) left on an object created by a craftsman.

The Arguments:

Classification of Ideas

Of the thoughts in his mind, Descartes considers that only judgements can, in themselves, be false. Of the other two types - images and desires - it is at least true that he is experiencing that desire or image (whereas with judgements, a decision is made about something which may or may not be true). For instance, to have a desire to eat an apple does not say anything about the existence of that apple, but to go to look for one does (so, the latter is a judgement that the apple exists).

All thoughts, he then considers, can be classed according to origin: whether from outside (adventitious); created by himself (factitious); or present from birth (innate). More specifically, judgements can also be classed in this way (as to whether such propositions assume the existence of external things, imaginary things, or concepts that the mind seems to be born with). Of course, he argues, one of these three categories may turn out to be the source for all thoughts (it may all be a dream, for instance).

Finally, concentrating on adventitious ideas, he considers how they arise. The two main assumptions which he finds himself possessing - that he has a natural desire to believe in their existence, and that they are not created by him - he ultimately rejects. This is because the natural tendency of believing things without sufficient proof or thought often misleads him, and because he is aware of an ability to create ideas and images of objects without those things existing in reality (such as in dreaming).

He has now cleared the ground for the trademark argument.

Clear and Distinct Ideas

Of the thoughts which Descartes finds in his mind, certain ones seem to possess more reality than others. So, for instance, the idea of a solid object such as a stone seems more real than processes such as heat or cold. Of these ideas, that of God seems to him to be the most clear and distinct of all.

This concept, central to Descartes's philosophy, is difficult to grasp. In trying to understand it, it is perhaps best to think of a 'clear and distinct idea' as one which is most strongly able to exist in the mind as an idea distinct from associations with the physical world.

From Descartes's point of view, such things as extension in space (size and shape), number (the fact that a thing is single, part of a group, etc.), and duration over time (the fact that a thing does not pop in and out of existence, and lasts for a certain period) are clear and distinct ideas. They are also primary qualities, or those things an object possesses which are not relative to an observer. However, the ideas of 'heat' and 'cold', colours, tastes, etc., seem to be less distinct: colours change according to light conditions; water may seem hot to a cold hand and cold to a warm hand; the same food can produce completely different reactions in different people, and tolerance for strength of flavour can differ greatly. These ideas are therefore secondary qualities of objects, and they are 'nothing in themselves' (as Descartes puts it), but merely a result of the mind interacting with an object.

Clear and distinct ideas are therefore very important for Descartes, in that they allow him to define what it is that makes something intellectually certain. Key examples of clear and distinct ideas are therefore the idea of God, the cogito, mathematical principles, and primary qualities.

The Trademark Argument

Firstly, Descartes concludes that all ideas must have as much reality in their cause as in their effect. By this he means that if we have a certain idea (in this case, 'infinity'), then the thing which caused that idea must have enough power ('reality') to produce such an idea in the first place (i.e. the thing which produced the idea of 'infinity' must itself be infinite). The way he phrases this is to talk about the 'formal' and 'eminent' properties of a thing. So, if I possess a quality formally, I have it as a consequence of the way I look (my form) - such as having black hair. However, if I possess a quality 'eminently', then I possess the power to produce that quality (an example would be the quality of being strong - I do not display it all the time, but I can when I want to. So, whatever produces the idea of God must either have the quality of infinity formally (it is itself infinite), or else eminently (be able to produce that idea). Therefore, if Descartes can prove that the idea does in fact contain a real idea of infinity, then he can prove that it must have come directly from God.

This he does by arguing that the idea of God cannot be linked to ideas he has of himself, because he (Descartes) is not infinite. He also rejects the idea that the idea he has of an infinite being may have arisen by simply thinking of the opposite of a finite being (i.e. the opposite of himself), because the idea of infinity seems both more real than that of being finite, and also to have originated first (since the idea of infinity is more clear and distinct, it is a more fundamental idea than that of a finite thing, which is imperfect). He then also rejects the idea that he himself might have created an idea of his own potential infinity - i.e. becoming eventually infinitely powerful, knowledgeable, etc. - arguing that something can never become infinite by degrees, because it would only ever increase in knowledge bit by bit (and, like Zeno's arrow, never reach it's target), whereas something infinite is actually without limit.

Therefore, the idea must come from outside him, cannot have come from nowhere, must have originated from an infinite being, and must have been left there almost like a trademark when the craftsman (God) made the object (Descartes himself). Therefore, God - who contains the quality of infinity both formally (he is infinite) and eminently (he can produce the idea of infinity) is the cause of the idea.

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