Why only mentalistic monism or dualism will do
Exapologist: Do you think Hasker is fair to Chalmers? Has he not read carefully? I strongly recommend Hasker's essay to anyone interested in retaining a common-sense view of the mental while remaining in any sense a naturalist.
It seems to me that these two options are just plain exhaustive:
1) The having of reasons, and other mental states are amongst the fundamental causes of the universe. The causal role cannot be explained in terms of the causal activities of more fundamental stuff.
2) Reasons and other mental states are system byproducts. They do not occur at the most basic level, but arise in virtue of the physical being a certain way.
It seems to me that if you accept 2) you have to live with three possibilities: elimination, conservative reduction, or epiphenomenalism. 1 seems to me to be self-refuting, 2 seems wildly implausible given the logical disparity between the mental and the physical, and 3 is also self-refuting since if it is true no one ever believes anything for a reason, including epiphenomenalism. Richard Carrier, Doctor Logic and Blue Devil Knight will give me an argument on this.
If you agree with me that these won't work, you have to accept a world-view in which reasons are on the ground floor. Theism is one of those alternatives. And if there is honest-to-goodness matter in the world (a mechanistic order of causes) then, in order for the mental to play a causal role in the physical world, you have to accept some kind of substance dualism. That's why I think substance dualism is a better account of the mind than any view, whether we call it physicalism or neutral monism, that says there is a physical realm in which reasons don't play a role, and that everything else supervenes on that.
So the question that one has to ask of any view of the mind is "What think ye of the causal closure of a realm in which reasons play no role?" Are reasons on the ground floor in your world-view, or not. There are alternatives to theism that do this, but those world-views strike me as forms of idealism. There just doesn't seem to be a way to be "neutral" on the question of whether reasons are basic to the universe. The only monism that will work, on my view and given my arguments, is is a mentalistic monism.