Philosophy 210/310
Early Modern Philosophy 
Andrew Mills' 
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The Second Meditation:
The Substance Theory and The "Cogito"

Begin with this fallacious argument

  1. Socrates is Socrates
  2. Socrates is snub-nosed
  3. Socrates is fat
  4. Socrates is wise
  5. So, one thing, Socrates, is many things (From 1-4)
The premises are all true, but the conclusion is clearly absurd.  What has gone wrong?  The argument has not distinguished between two senses of the term "is".  (1) and (5) use the "is" of identity (Mark Twain is Samuel Clemens, Superman is Clark Kent), while (2), (3), and (4) make use of the "is" of predication: the "is" that we use to ascribe properties to things.

The moral is that we need to distinguish between things (Socrates, Mark Twain, the apple in my hand) and properties (fatness, wisdom, snub-nosedness, redness, etc.).  The question that arises is this: What is the relationship between things and their properties?  Here are two answers:

The Bundle Theory: A thing is merely a collection of coexisting properties. An apple is nothing but roundness, redness, tartness, hardness, etc. co-existing at a certain place and time.

The Substance Theory: A thing is composed of various properties plus an underlying substance to which these properties belong.

Descartes endorses the Substance Theory (we will see it rejected by Berkely and Hume, and endorsed by Locke).  We can read the wax argument at the end of the meditation as an argument in favor of the Substance Theory, and that argument might be reconstructed thus:

The Argument from Change

  1. We can distinguish between (a) all of a thing’s determinate properties changing without the thing’s ceasing to exist and (b) a thing’s ceasing to exist.
  2. We can distinguish between (a) and (b) only if a thing is composed, in addition to its properties, of a permanent, underlying substance
  3. So, A thing is composed, in addition to its properties, of a permanent underlying substance. (From 1, 2)
It has been suggested that we read the "Cogito" argument--the inference from "I'm thinking" to "I exist"--as making use of the Substance Theory.  Here is the reconstruction:

A Reconstruction of the Cogito

  1. A thing is composed of its properties or characteristics plus an underlying substance to which they belong (Substance Theory)
  2. If there is a property or characteristic, then there must be a substance to which it belongs (From 1)
  3. A thought is a property (Assumption)
  4. If there is a thought, then there is a substance to which it belongs. (From 2, 3)
  5. There is a thought (Assumption)
  6. So, there is a substance to which this thought belongs: "I" (From 4, 5)
(Arguments taken from George Dicker, Descartes)