Where Your Moral Sense Came From

The newest challenge in this book does not argue about definitions, or about what moral facts would be. It asks where your moral reactions came from.

The answer, as far as anybody can tell, is natural selection. The dispositions you feel when you see cruelty, or unfairness, or somebody defecting on a bargain, are not inventions of your own reasoning. They are equipment, and the process that installed them selected for what helped ancestors survive and reproduce in small groups.

That process had no interest whatsoever in whether the reactions were correct.

Here is why that matters. Suppose a belief of yours is entirely explained by a process that is insensitive to whether the belief is true. Then the fact that you hold it gives you no evidence that it is true, even if by chance it happens to be.

An example makes the shape clear. If you learned that a pill had been slipped into your drink which causes the firm conviction that there is a tiger in the next room, the conviction would give you no reason to believe in the tiger. There might be a tiger. Your believing it has stopped being evidence.

The debunking argument says moral intuitions are in that position.

Notice what it does not claim. It does not claim your moral beliefs are false. It attacks their justification, and that is worse in a specific way. A false belief can in principle be discovered and corrected. An undermined justification takes away the ground you would stand on while doing the checking, because the checking would be done with the same equipment.

And it strikes at exactly the right target. Almost every moral argument in the rest of this library bottoms out in a case that strikes you a certain way. The trolley problem is an argument only because your reactions to the two versions differ. Remove the standing of those reactions and the structure above them has nothing underneath.

The strongest reply is that the argument proves too much.

Your mathematical intuitions were produced by the same process. So was your capacity for logical inference, your sense that the future will resemble the past, and your confidence in your own perception. None of these was selected for tracking truth as such; they were selected because they worked.

If evolutionary origin undermines justification, it undermines all of that, including the reasoning used to construct the debunking argument. An argument that general has usually gone wrong somewhere, and locating exactly where is an active problem rather than a settled one.

Now step back and look at what these four chapters have done.

Hume found a gap in the reasoning. Moore found that the definitions offered to close it all fail a simple test. Mackie concluded that the subject matter the whole enterprise presupposes does not exist. The debunker attacks the evidence that would settle the question either way.

Each is more radical than the last. Each is still live. There is no agreed answer to any of them.

And meanwhile, not one person in any of these camps thinks that torturing a child for entertainment is fine.

That is the fact any complete account has to explain: the arguments get more corrosive and the conviction does not move. Whatever is going on in moral thought, it is not resting on the foundations that four hundred years of philosophy have failed to find for it.