Monday, September 24, 2012

Good reasons, naturalism and evolution

Start with these three facts:

  1. I have good (prima facie) reason to promote my own survival.
  2. I believe (1).
  3. I know (1).
Now, there is an excellent evolutionary explanation of fact (2). Beings that act on what they take to be reasons are unlikely to survive long enough to reproduce unless they take promoting their survival to be a good prima facie reason. However, this evolutionary explanation does not appear to have much connection with the normative fact (1). Thus, if this evolutionary explanation of fact (2) is the whole relevant story, then it is a mere coincidence that my belief that survival is reason-giving happens to be true. But then my belief isn't knowledge—it is at best a case of justified true belief, contrary to (3).

This means that the evolutionary explanation of fact (2) isn't the whole of the relevant story about why I have the belief that promoting my survival is worthwhile. We need, thus, an explanation of fact (2) that connects that belief with the normative fact (1). I doubt that naturalism can provide such a connection. Theism, on the other hand, can. For God could have deliberately created us in such a way that evolutionary processes would lead us to true belief in (1). On this theistic evolutionary story, it is no coincidence that (a) we believe proposition (1) and (b) proposition (1) is true. Thus, this story is to be preferred to a naturalistic one.

But what if the naturalist denies that (1) is true? Then she either does not believe that she has reason to promote her survival or she does. If she does believe it, then she contradicts herself—she believes something that she takes not to be true! But if she does not believe it, then for what reason does she act in her daily life as if she had reason to promote her own survival?

What I like about this argument is that it takes what seems an obvious strength of naturalistic evolution, namely its ability to handily explain facts such as (2), and turns it into a liability.


Heath White said...

Interesting. I have a couple of worries. The first is the inference in the second paragraph to “the evolutionary explanation of fact (2) isn't the whole of the relevant story about why I have the belief”. I can see why you think the evolutionary explanation can’t be the knowledge story. I cannot see why you think it cannot be the belief story.

A second worry, in the third paragraph: if I were a naturalist, I think I would say that (1) is true, invoking some constructivist form of metaethics. E.g. it is true because it satisfies my reflective desires, or because I think it is, etc.

If you have not read it, you might want to look at Sharon Street, “A Darwinian Dilemma for Realist Theories of Value.” It runs essentially your argument, plus naturalism, in order to reach the conclusion that moral realism is false.

Alexander R Pruss said...


Well, if the evolutionary story about (2) were the whole story, (3) would be false. But (3) is true.

I don't think constructivism has any hope of being true. To invoke it here to avoid the existence of God (or similar guidance on evolution) is sort of like going for scientific anti-realism to avoid commitment to electrons.

Thanks for the reference. There are a number of papers along those lines concerning morality, too. It's interesting that none of the ones I looked at even considers theism.

Alexander R Pruss said...

By the way, if one says that (1) is true and invokes a constructivist metaethics, then one may be equivocating on "true" or have to have a theory of truth that's at most in part realist.

Schimpfinator said...

Wouldn't the naturalist bite the bullet and be an anti-realist about reasons? The sense of reason in #1 is objective in a way that a serious naturalist would object to. This point seems like the crux of the rationalist / empiricist distinction.

Schimpfinator said...

But of course, what I love about this argument is that it brings together the interconnected nature of normative and descriptive claims.