Peter Singer

So, you know, Jonathan Haidt has an example where he talks about a case of adult sibling incest.

So...

an adult brother and sister who are alone on a holiday somewhere in a remote place decide it would be fun to have sex.

They have sex, they enjoy it, but they say, yeah, okay, but we don't need to do that again.

We've had that experience and they remain close as a sibling, as siblings.

Was there something wrong with that?

And when Haidt, who was a psychologist rather than a philosopher, asked his students and experimental subjects, they said,

Nearly all said, oh, yes, that's wrong.

And then Haidt would say, well, why is it wrong?

And they would say things, oh, like because they might have children who are abnormal.

But actually I didn't spell this out, but in the example they used, although the woman was on the pill, the sister was on the pill, but the brother decided to use a condom as well, so there was really no chance that they were going to have an offspring.

And then they might say, well, it could hurt their sibling relationship, but they were told in the example that it didn't.

they can't really explain, but they just have this deep instinct that incest is wrong.

Okay, well, we can explain why they have that instinct, that intuition, but it doesn't give us any reasons for thinking that what this couple did was wrong.

Right.

So, I mean, what you're talking about really sounds like the idea of reflective equilibrium that John Rawls put forward in A Theory of Justice, that we develop a theory or a basic starting point for foundation for moral theories, and then we test the theories against our intuitions, and then

we either tweak the theory to produce better intuitions or we tweak the intuitions to match the theory.

Rawls originally suggested this was a little bit like a scientist trying to produce a theory to match the data.

And if there are a couple of points of data that the theory couldn't match, well, then you perhaps rejected that data.

You said, well, there must have been something wrong with that observation.