Perhaps the idea of a mentalistic explanation requires some explanation. A moment ago I went out to get the mail. I believed that getting the mail would be a good thing, I know where the mailbox is, and so I fulfilled my intention to go out to the mailbox and get the mail. My actions had a purpose which I fulfilled. My feet moved, due to signals sent from my brain, but the ultimate reason why the atoms in my brain did what they did is that because they were directed by something possessing a purpose. Or, perhaps the atoms themselves had an inherent purpose. Something desired by some entity brought it about that the atoms moved the way they did.
But these types of explanations are
typically excluded from basic physics. In fact, not only purpose, but
intentionality or about-ness, normativity, and first-person perspective are
also excluded. The four fundamental forces
postulated by physics, gravity, electromagnetism, and the strong and weak
nuclear forces, are blind forces, which do not act for reasons. If gravity
operates on boulders falling in an avalanche, they will neither avoid my head
to spare my life nor strike me to punish my wickedness. No, the gravitational force has no mental life,
and genuinely physical particles have no mental life either. But what happens
at the mindless level of basic physics, according to materialism, determines what
goes on at all levels. It is true that physical events sometimes produce
results that an intentional agent would choose, indeed that is how natural selection
works. But in the final analysis, if materialism is true, it looks as if the
idea of intentions or purposes or desires or motives producing actions is bound
to be an illusion.
