Four Features of the Mental
There are four features of the mental which someone who denies the ultimacy of mind maintain must not be found on the rock bottom level of the universe. The first mark of the mental is purpose. If there is purpose in the world, it betokens the existence of a mind that has that purpose. So for anyone who denies the ultimacy of the mind, an explanation in terms of purposes requires a further non-purposive explanation to account for the purpose explanation. The second mark of the mental is intentionality or about-ness. Genuinely non-mental states are not about anything at all. The third mark of the mental is normativity. If there is normativity, there has to be a mind for which something is normative. A normative explanation must be explained further in terms of the non-normative. Finally, the fourth mark of the mental is subjectivity. If there is a perspective from which something is viewed, that means, once again, that a mind is present. A genuinely non-mental account of a state of affairs will leave out of account anything that indicates what it is like to be in that state.
If the mind is not ultimate, then any explanation that is given in terms of any of these four marks must be given a further explanation in which these marks are washed out of the equation.
IV. Minimal Materialism
There seem to be three minimal characteristics of a world-view which affirms that the mind is not ultimate. First, the “basic level” must be mechanistic, and by that I mean that it is free of purpose, free of intentionality, free of normativity, and free of subjectivity. It is not implied here that a naturalistic world must be deterministic. However, whatever is not deterministic in such a world is brute chance and nothing more.
Second, “basic level” must be causally closed. Nothing that exists independently from the physical world can cause anything to occur in the physical world. Second, the level of basic physics must be causally closed. That is, if a physical event has a cause at time t, then it has a physical cause at time t. Even that cause is not a determining cause; there cannot be something non-physical that plays a role in producing a physical event. If you knew everything about the physical level (the laws and the facts) before an event occurred, you could add nothing to your ability to predict where the particles will be in the future by knowing anything about anything outside of basic physics.
Third, whatever is not physical, at least if it is in space and time, must supervene on the physical. Given the physical, everything else is a necessary consequence. In short, what the world is at bottom is a mindless system of events at the level of fundamental particles, and everything else that exists must exist in virtue of what is going on at that basic level. This understanding of a broadly materialist world-view is not a tendentiously defined form of reductionism; it is what most people who would regard themselves as being in the broadly materialist camp would agree with, a sort of “minimal materialism.” Not only that, but I maintain that any world-view that could reasonably be called “naturalistic” is going to have these features, and the difficulties that I will be advancing against a “broadly materialist” world-view thus defined will be a difficulty that will exist for any kind of naturalism that I can think of.