> We long for a real basis for morals, but if all we are is matter obeying the laws of physics, morals cannot be anything more than arbitrarily-made-up rules.
That's not necessarily true: http://plato.stanford.edu/entries/moral-realism/#2
That's not necessarily true: http://plato.stanford.edu/entries/moral-realism/#2
As Sam Harris said, either I'm a deterministic machine, or I'm a random machine, but in neither case do I have moral responsibility for what I do.
First off, naturalism does not necessarily imply determinism. But even given physical determinism, the incompatibility of it and free will is not a certainty:
http://plato.stanford.edu/entries/compatibilism/
The point I'm really trying to make is that there are a lot of smart people who have written on all these topics, and the answers are far from settled.
As for compatibilism... it looks like "you can't totally prove that materialism implies no free will, so it might be possible." No mechanism, not even a guess at one, just "it could still be". Forgive me, but I don't find that very persuasive.
I think that my objection to most of the compatibilism stuff is this: What is the "I" that is going to choose? In a purely naturalist view, all I can be is a collection of matter that obeys the laws of physics, because there's nothing else for me to be. I'm a machine made out of atoms, nothing more. It seems to me that all these compatibilist arguments aren't really taking that seriously. (Perhaps not surprisingly, since they're being made by philosophers, not physicists.) They therefore have some intuitive, experience-based idea of what a person is that sneaks in to their arguments, rather than really grappling with the implications of the purely naturalist position.
Another good question!
http://plato.stanford.edu/entries/identity-personal/
> It seems to me that all these compatibilist arguments aren't really taking that seriously. (Perhaps not surprisingly, since they're being made by philosophers, not physicists.)
They are. Nothing about naturalism implies "I'm a machine made out of atoms, nothing more." Even granting that I am a machine made out of atoms, I'm not just that. I possess other properties than just being a machine made out of atoms--e.g. those atoms are in a particular location, they can affect other sets of atoms, etc.
Going back to the original point, there's nothing innate about sets of atoms that implies they can't also be the subject of moral assertions. I understand that you may not intuitively agree with this position, but there's nothing about sets of atoms that logically rules out this possibility.
You should actually study the philosophy before dismissing it.
To me, the physics is pretty convincing. I don't care that philosophers object "but you can't totally rule it out!". There's lots of things I can't totally rule out. That doesn't mean that they should be seriously considered.