  As we noted earlier, functionalism characterizes states of mind causally. To be in a given mental state is to be in a state with the right sort of causal profile, a state bearing the right sorts of relation to other states. Think of functional states as nodes in a network of states, the identity of which depends on the relations they bear to other nodes, and think of the realizers as occupants of these nodes. All there is to a node is the potential causal relations it bears to other nodes (not so for the occupants, which have intrinsic properties). Suppose, then, that F and G are functional properties—nodes in this network—and that all there is to something’s being F is its being a G-causer. The resulting generalization, “Fs cause Gs”, is no doubt true, but it is vacuous, equivalent to the generalization that G-causers cause Gs.