- Parsimony. It is simply more parsimonious to conclude that everything is matter, in line with what science has discovered so far. And a non-physical "soul" is not parsimonious.
- Transitive arguments. Pain is the behavior of screaming, running away, etc. And that behavior consists of C-fibers firing (or whatever). Therefore, pain is the firing of C-fibers. In other words: Pain = behavior = C fibers, therefore pain = C fibers.
- We ought to believe something exists only based on its causal powers. If it can't cause anything, then there is no reason to believe it exists. Because of the causal closure thesis of physics, that all physical effects have physical causes, this leads directly to materialism.
- Conscious causes have physical effects. From physics, we know that all physical effects have physical causes. Therefore, consciousness is physical.
And as Lycan says, "I know of no other arguments for materialism." Of course, he also shows why the above arguments don't work.