Thursday, March 15, 2007

You wouldn't expect it...

I more or less recently ran into a charming display of 'absentmindedness' on the part of the type of person you'd least expect to write something so trivially wrong, or at least you'd think that he would ask someone to double-check the work in question before tagging his name on it.

Consider the following article: Writing Descartes: I Am, and I Can Think, Therefore ... by one Professor Paul Grobstein, Harvard grad, Harvard PhD, and impressive academic record in the field of biology. The man is clearly an intelligent fellow, and thus possibly the last person you'd expect to produce the following pearl of wisdom as an argument against Cartesian Skepticism (emphasis mine):

Your phrase "I think, therefore I am" needs some correcting. I think I understand what you had in mind: the need to find a solid footing for ongoing inquiry. And I very much admire your posture of profound skepticism, with its associated reluctance to take not only "revealed truth" and authority but also logic and sense data as an assured starting point. It does seem to me though that you (or, more likely, others since you) took a good idea too far (as happened with your mind/body distinction, see Descartes' Error). Or, maybe, it wasn't taken far enough.

Here's the thing. Trees are. And they don't "think". So you can't have meant to say that things in general have to think in order to be. That would be contradicted by trees and other things (rocks, desks, etc) that you certainly knew about.

He then goes on to make some potentially interesting comments about scepticism, which unfortunately here stem from this initial assumption that 'Descartes got it wrong' (I don't argue that he didn't, but certainly not on these grounds). And while these comments are not necessarily without merit or value (were they to be made independently of talk about what Professor Grobstein thinks is Descartes' position), his initial critique of Descartes' cogito is horrendously wrong.

Consider the general form of a syllogism:

Premise 1: If P, then Q
Premise 2: P

Conclusion: Q

Now here's basically what Professor Grobstein believes Descartes' cogito to entail (and what he criticises):

Premise 1: If P, then Q
Premise 2: Not P

Conclusion: Not Q

Now, any ol' undergraduate having done a very basic introduction to logic will tell you that the logical statement 'P therefore Q' is false if and only if P is true while Q is false. This is to say that 'P therefore Q' is perfectly true if P is false, but Q is true. Professor Grobstein is thus committing a basic non-sequitur in claiming that 'P therefore Q' entails '(Not P) therefore (Not Q)'. It would be a valid entailment if Descartes had said something mapping to the logical statement 'P if and only if Q', but as Descartes did not in any way say "I think if and only if I am" (or vice-versa... it doesn't really matter), Professor Grobstein doesn't really have a leg to stand on for his argument.

It just goes to show: when shopping around for academic wisdom, caveat emptor.

Of course, this isn't exactly a published paper, just an open letter on his website. Still, it does not excuse the need for a bit of peer-review (I'm sure he could have nabbed a first year computer scientist, or a philosophy student), so as to avoid slightly embarrassing, simple mistakes such as this one.

To conclude, I do not wish to give the impression that I claim non-philosophers (and specifically scientists) should stay away from philosophy. If anything, one should encourage them to practise it. Nonetheless, if you're going to go up against a central, well-known position of philosophy (and by all means, please do!), at least make sure your argument doesn't fall apart because of some trivial misunderstanding of logic.

4 comments:

Sinatra_Z said...

Suddenly Differential Equations dosent seem that hard.

Ed said...

... were they ever? I kid, I had trouble with them in high-school (but then again, didn't do much work then).

Logic only seems scary because it's unfamiliar (to some), but I assure you it's very easy (at least the application of deductive-methods and whatnot) once you get into it a bit...

Paul Grobstein said...

Pleased you found "some potentially interesting comments about skepticism" in Writing Descartes. There are, I think, some big fish to fry in this realm (cf Getting it Less Wrong: the Brain's Way, Revisiting Science in Culture, and The Nature of Science).

Yes, indeed, Descartes did not say that one had to think in order to be. But he did, perhaps unintentionally, trigger an extended tradition of western thought that presumed that thinking was prior to or at least independent of being. It was that, rather than Descartes himself, that was one of the targets of the essay. And I don't think it, or the larger argument for a skepticism that may well excede that of Descartes, stands or falls on what was intended not as a logical argument but a conceptual one.

Caveat emptor indeed. But let's also try and avoid throwing out babies with bath water?

Edward said...

Dear Prof. Grobstein,

Pleased you stumbled across this page and took the time to comment. There are indeed "some big fish to fry in this realm", and it might be worth pointing out that the kitchen has been quite full of philosophers discussing the issue of scepticism, and more broadly of the relation between existence and essence (and therefore cognition).

There's certainly no harm in attacking substance dualist positions, or in asking questions concerning the seat and origin of our cognitive capabilities, and of their development. I don't believe I've implied this at any point in my post. I merely made a methodological point with regards to argumentative structure: that as good as an argument is, in substance, it should start as strong as it ends, otherwise it is merely invalid and therefore potentially unconvincing to those unwilling to correct the premises. This, or course, does not mean that it could not be made convincing, nor does it mean the conclusions are untrue. I therefore fail to see why I am "throwing the baby out with the bath water".

I am, after all, not unsympathetic to the point that you are making, which essentially states that our acts and beliefs can redefine our identity, and that self-identity is therefore a dynamic notion (rather than something which necessarily exists, pure and eternal, outside of our bodies). The issue is simply that a logically shaky (to be kind) interpretation of the Cartesian cogito doesn't really positively contribute to an argument formatted as an open letter to Descartes.

Best,
Edward.