A Defense of Physicalism, from causal closure of physics
The main argument against physicalism is that it really seems impossible for pure matter to arrange itself in such a way as to produce consciousness. Therefore, solutions are proposed in the form of dualism, property dualism, panpsychism, and so on.
A physicalist would say agree that this hard problem of consciousness is not trivial, but why should it be impossible? Until we have fully understood the brain, is it not premature to declare whether pure matter is capable of producing consciousness? The universe is under no obligation to conform to our intuitions.
Here is a hint that solving the problem physically may not be impossible. Humans are able to speak about consciousness and a first-person perspective, and qualia and so on.
Why do we do this? Because consciousness is real and can physically affect the brain to cause it to speak about such matters.
Violating the laws of physics, or amending it to allow a nonphysical consciousness to affect a physical brain is surely the last resort. Is it not better to explore the physical possibilities first, even if it really, really seems like there is no way for it to work?
I guess my disagreement with nonphysicalists is over how they are so confident a physical explanation will never be found. I would place maybe a 95% confidence on a physical explanation because my intuitions accept as more likely a really clever way for matter to organize to form consciousness rather than making exceptions to causal closure just for this phenomenon of consciousness.
Maybe if you are religious in some way, a nonphysical position, I can understand. But plenty of nonphysicalists are pretty much completely nonreligious, and this I find interesting.