Professor Heathwood's Cartesian Parody

The point of crafting a parody argument is to show that an absurd conclusion follows using the same exact logic as the argument you are trying to refute. For this strategy to work, though, you better make sure your parody argument is following the same exact logic.

A Peculiar Parody

In my experience, parody arguments are rarely successful because they often overlook a distinction that renders the two arguments dissimilar. A great example of such an oversight is Professor Heathwood’s attempt on his University of Colorado page to parody Descartes’ famous Argument From Doubt. Descartes’ argument, according to Professor Heathwood, has the following form:

1. Descartes has an existence that cannot be doubted by Descartes.
2. Descartes’ body has an existence that can be doubted by Descartes.
3. If (1) and (2), then Descartes is not identical to Descartes’ body.

Therefore, Descartes is not identical to Descartes’ body.

The key to premise (3) is Leibniz’s Law, a foundational metaphysical principle that virtually all philosophers accept. It states that for any A and B, if A is identical to B, then whatever is true of A is true of B and vice versa. It is easy to see why this principle is uncontroversial, since how could A be any different than B if A is B? Another way of putting this principle is that if A is identical to B, then whatever properties are had by A are had by B and vice versa.

With Descartes’ argument thus formulated, Heathwood outlines his parody argument as follows:

1. Superman is such that Lois Lane wants to marry him.
2. Clark Kent is not such that Lois Lane wants to marry him.
3. If (1) and (2), then Superman is not identical to Clark Kent.

Therefore, Superman is not identical to Clark Kent.

Heathwood notes that since the parody argument leads to a false conclusion, there must be something suspect about Descartes’ argument too. As Heathwood points out, the problem lies in the fact that Superman and Clark Kent supposedly have different properties:

The property that Superman allegedly has and Clark Kent lacks is this: being such that Lois Lane wants to marry him. IF in fact Superman has this property and Clark Kent lacks it, Leibniz’s Law says that Superman can’t be identical to Clark Kent.

So, the problem is supposed to be that Superman and Clark Kent have conflicting properties. But is this argument really logically equivalent to Descartes’ argument? I think the parody fails for a few reasons.

Problems With The Parody

The first thing to note is that, in the parody argument, the properties in question really aren’t properties of Superman or Clark Kent, but of Lois Lane. It is Lois Lane that has the property of wanting to marry X or not wanting to marry X. So the fact that Lois wants to marry Superman but not Clark Kent only shows that she doesn’t know that Clark Kent is Superman, not that Clark Kent and Superman have different properties.

This is in contrast to Descartes’ argument, in which both premises of the argument are making claims about Descartes himself. Descartes is the one whose existence cannot be doubted, but he is also the one doing the doubting. In short, Descartes’ argument as found in the Meditations is famously formulated in the first person, something which Heathwood’s parody argument fails to take into account. The “first person” is one of the things that is distinctive about consciousness, so we can’t just ignore that feature of Descartes’ argument!

The second problem with the parody argument is that it fails to take into account the fact that Descartes’ argument contains modal propositions. The claim that Descartes is making is that his existence cannot be doubted – it is not even possible to doubt. That is a modal claim about what is possible or not possible. There is no such modal claim being made in Professor Heathwood’s parody argument. Leibniz’s Law applies to modal properties as well, so if something is possible for A that is not possible for B, then A cannot be identical to B.

The fact that Descartes’ existence has the modal property “cannot be doubted by me” but Descartes’ body does not have the modal property “cannot be doubted by me” is a real distinction that warrants an explanation. The explanation classically offered by Descartes is that this is because he is not identical to his body.

In conclusion, I think we have seen that nothing in Professor Heathwood’s parody argument shows that Descartes is wrong. Don’t beat yourself up, Professor Heathwood. It’s hard to butt heads with a philosophical and mathematical genius like Descartes, after all!

Happy philosophizing everyone!