Thursday, September 25, 2008

A false principle concerning desire

I am not the first to discover this particular fallacy—in fact, part of this post is based on ideas I got in conversion from somebody who got them from something he read. But the ideas are no less fun for being mainly not mine.

Consider the following argument for psychological hedonism, the doctrine that the only thing we pursue is pleasure:

  1. Whenever we pursue something other than pleasure, we pursue it because it gives us pleasure. (Premise)
  2. Therefore, what we really pursue is the pleasure it affords to us.
Not only is (1) false, but (2) does not follow from it. The following inference is invalid:
  1. We pursue x because it gives us y.
  2. Therefore, what we really pursue is y.
In fact, taken literally, (4) contradicts (3), since if "what we really pursue" is y, and y is not x, then we are not pursuing x (to pursue is the same as to really pursue). But even if we weaken (4) to:
  1. Therefore, we pursue y
the inference is still invalid. If I am trying to find a woman who offers water to my camels (cf. Genesis 24), it does not follow that what I am really pursuing is water for my camels. Perhaps I just want the kind of woman who gives water to my camels. Likewise, one might want a particular fig tree in the garden because it yields figs, not because one wants the figs, but because yielding figs is largely constitutive of the health of a tree, and one wants only healthy trees in the garden.

Perhaps the inference works better if we replace (1) by:

  1. Whenever we pursue something other than pleasure, we pursue it only because it gives us pleasure.
It's easier to see how (2) might be thought to follow, but (6) now begs the question against the non-hedonist. In any case, the inference is still logically invalid.

In fact, it is even incorrect to conclude from the claim that I seek x solely because it yields y that I want y at all. Suppose that, whimsically, I desire a magical hat that yields rabbits. I only want the hat because it yields rabbits—my whim is that I want to have rabbits pop into existence out of a hat. I can want such a hat for such a reason without having any desire for the rabbits. The rabbits themselves are a nuisance, and I would have no interest at all in rabbits that come into existence in any way other than out of a hat.

It might be objected that then I don't want the hat just because it yields rabbits, but I want the hat because it is a hat that yields rabbits, and so this isn't a counterexample to the inference type. But if so, then the non-hedonist need only say that she doesn't want x just because it yields pleasure, but she wants an x because it is an x that yields pleasure.

The fallacy here also occurs in the Lysis in the argument that if I am friends with x because x yields y, then what I am really friends with is y.


Heath White said...

I suspect that if you use "in order to" to frame the principle, as in "Whenever we pursue X, we pursue X in order to get pleasure" you will eliminate a lot of these fallacies.

Alexander R Pruss said...

Doesn't that make the argument more question-begging, though?

Ryan said...

I feel like I'm missing something. How do you keep your criticism to extending to all reasoning about means and ends? If I choose a particular end, I then must deliberate about the best means to accomplish that end. I then pursue, or seek to accomplish, those means. Am I not only pursuing those means for that end?

To complicate the case, if what I want is an end accomplished by certain means then that complex, the end and its means, is the true end being sought, e.g., I don't merely want the 'end' of my wife cooking me supper, but want that to come about by the means of her love motivating her to provide for me, I wouldn't want the end if I had to physically force her.

If you're taking 'pursue' to necessarily be bound up with the nature of an end, so that you can never properly 'pursue' a means, then that seems well and good. But I took you to be saying something else.

Heath White said...

Well, since it's a one-step argument, either the premise will be question-begging or the argument will be invalid. For my money, there is nothing anywhere in the neighborhood of psychological hedonism that is true.