Full Idea
The dominant empirical argument for physicalism is the Overdetermination Argument: physics is closed and complete, mind is causally efficacious, the world isn't choc-full of overdetermination, so the mind is physical as well.
Gist of Idea
The main argument for physicalism is its simple account of causation
Source
Scott Sturgeon (Matters of Mind [2000], Intro)
Book Reference
Sturgeon,Scott: 'Matters of Mind' [Routledge 2000], p.3
A Reaction
I find this argument utterly convincing. The idea that there is only one thing which is outside the interconnected causal nexus which seems to constitute the rest of reality, and that is a piece of meat inside our heads, strikes me as totally ridiculous.