The Nature of Ideas in the Third Meditation

WHAT DESCARTES SAYS

In his Meditations on First Philosophy, René Descartes, in the Third Meditation, writes:

So it is clear to me, by the natural light, that the ideas in me are like pictures, or images which can easily fall short of the perfection of the things from which they are taken, but which cannot contain anything greater or more perfect.

In other words, it seems that Descartes claims that ideas are like pictures insofar as they are less great or less perfect than the reality from which they stem.  It follows, then, that Descartes believes that it is impossible for an idea to be greater or more perfect than the reality that causes it.

POTENTIAL OBJECTION

One might disagree with the above claim made by Descartes and counter that it is indeed possible for an idea to exceed the reality in greatness or perfection.  This person, when offering his objection, might put forward counterexamples in the form of two thought experiments.

1. Imagine a man who lives in a small village.  He was born in the village, raised in the village, and has lived in the village for his entire life.  In fact, he never has ventured outside of the village; and what is located in the village is all that he knows.  The tallest structure in the village is a two-story house.  Every other structure in the village is a single floor.  Now, according to Descartes, no idea can be greater than the reality from which it comes; however, it seems completely reasonable to believe that it is possible for the man to have an idea of how a three-story structure would look and be built.  A three-story structure is greater in size than a two-story structure.  Thus, it is possible, contrary to what Descartes claims, for the mind to have a picture or image of something that is greater (a three-story structure) than the thing from which it is taken (the two-story house).

2. A young girl is taking her first class in mathematics, and she is being exposed to some basic geometry; the main thing that she is being taught are the shapes and their names.  Now, her teacher is quite old and has an unsteady hand; all of the lines that he draws on the chalkboard are always crooked.  The young girl never has seen a perfectly straight line.  However, based on the crooked lines that she has seen the teacher draw on the board, it seems completely reasonable to believe that it is possible for the girl to have an idea of a perfectly straight line (how it would look).  A straight line is more perfect than a crooked line.  Thus, it is possible, contrary to what Descartes claims, for the mind to have a picture or image of something that is more perfect (a straight line) than the thing from which it is taken (the crooked lines drawn by the teacher).

WHAT DESCARTES LIKELY WOULD REPLY

In reply to the above objection, it is likely that Descartes would say something like this:

Well, in response to the second thought experiment that you offer, you should have continued reading because, in the Fifth Meditation, I write, “I find within me countless ideas of things which even though they may not exist anywhere outside me [for example, a perfectly straight line] still cannot be called nothing; for although in a sense they can be thought of at will, they are not my invention but have their own true and immutable natures.”  In the case of a line, the crooked lines that the teacher has drawn on the chalkboard are not the reality from which the girl conceives of how a perfectly straight line would look.  The image that the girl has in her mind comes from the true and immutable nature of a straight line.  This idea is conveyed to the girl by her teacher, who likewise has an image of a straight line in his mind; although, he cannot draw one.  The idea that the girl has of a straight line comes from the exact same idea that her teacher has of a straight line.  The idea of the girl is not more perfect than the idea of her teacher.  The idea of the girl does not contain anything more perfect than the thing from which it is taken (the idea of the teacher).  Both ideas are equal in all respects.

In reply to your first thought experiment, I did not intend the word “greater” to mean greater in size; rather, when I was writing, I intended the word to mean greater in the sense of quality.  In the Third Mediation, I use “greater” in a qualitative sense, not a quantitative sense.  With respect to quality, a three-story house (although it is larger) is no better than a two-story house.  Bigger does not mean better.  The word “greater,” as I meant to use it, should be considered the same as “more perfect.”  It refers to the quality of something, not its quantity.