How does the spook interact with solid matter? How does an ethereal nothing respond to flashes, pokes and beeps and get arms and legs to move?
Ah yes, the interaction problem. Is that still around? Apparently so.
In one way, it’s hard to see how this problem arises: souls are forms, and so if this were really a problem, then there would also be an interaction problem for basketballs: How does a sphere interact with solid rubber? How does a Euclidean solid respond to the molecular structure of hydrocarbons? What an untenable dualism!”
But isn’t the soul a form in the substantial order, and not in the accidental order? Yes, but this still doesn’t give a duality of substances. Thomists don’t believe that the body has a substantial form that the soul is added to. The substantial character of the body is simply a certain emanation from the soul, and is lost immediately at death. “Corpse” is not the name of some one thing, but of a heap of things that have no actual relation to one another. Where is the duality? Interaction problems are between two things, but there simply are not two things here.
It turns out that soul-as-Stephen-Pinker understands it is a silly and mythical entity that owes its existence to Stephen Pinker (or any of us) being deceived by false imagination. First, we turn forms into things simply speaking; when in fact forms are certain things only with qualification that are necessary to explain what we call things simply speaking. If the verbiage there is too dense, just ask yourself if the roundness of a basketball a thing without any qualification. When you see a basketball, do you say that you see two things, a basketball and its roundness? There is also a second deception by false imagination that Pinker manifests by his “spook” talk. Pinker is clearly conceiving immateriality as a kind of material existence- for it is precisely as material that beings exclude each other, become impenetrable to one another, and can only assimilate others by destroying them (that is, by digesting them). Immateriality is a negation of exactly this sort of exclusion that one is tacitly assuming when he posits an interaction problem between spirit and matter. Immateriality is (self evidently) the negation of material parts, and whatever lacks material parts cannot be excluded or rejected by the material parts of another, any more than a triangle is destroyed by adding a point to it. So even if one said that the material body and the immaterial soul were two substances simply speaking, there would be no problem of how one interacted with the other by perfectly penetrating and incorporating itself into it, since immateriality removes the impediment to this perfect penetration.