Spinoza has what is called a "double-aspect" theory of mind. Spinoza argues that the universe is both the mind and the body of God. Thus everything comes under both a physical and a psychological description. This is a promising line of argument for philosophy of mind: if Spinoza is right, our project is not to reduce or translate the psychological to the physical. (A puzzle is what is called Spinoza's "panpsychism": on his view everything comes under both descriptions. What seems promising in the case of humans is just mysterious when said about, say chairs.)
Last week during class it occured to me that Jerry Fodor elaborates a line of reasoning that has some striking similarities to Spinoza. (I'm writing this here in class with the students, by the way.) Fodor's idea is that the semantic properties of the intentional mental states/processes and the physical causal properties of the brain states/processes might come together at the level of syntax. In a way Fodor pushes the approach further than Spinoza: his appeal to the formal structure of the grammar of the proposition, on the one hand, and the formal structure of the physical causal mechanism, on the other, could serve as the bridge between the two "aspects" (descriptions), thus producing "psychophysical laws," lawful relations between the two kinds of formal organization.
Notice that it's going to turn out that the brain (or nervous system, or body, or what have you) is also formally organized. My view is that (so far at least) this is right, and important: traditionally (Plato, Descartes) the formal structure of the rational mind was a metaphysical bar to translation between the intentional and the physical. But for an approach like Fodor's to work, it must be that the physical system is also something that comes under a formal description. It is the two formal descriptions that might map onto each other. If this is true than we can draw two conclusions.
First, there is no metaphysical problem here that is unique to the philosophy of mind. The rational structure of thought is (just) another instance of the formal structure of physical objects in general. The question about why the physical universe is formally organized may be interesting and important, but once we see that it is a general metaphysical problem we have effectively overcome this particular problem qua a problem for philosophy of mind.
Secondly, another bit of mysterious 17th century philosophy is called to mind: the "synchronicity" of Leibniz and Malebranch. Here the idea was that some third causal power (they used "God" here in a technical sense) has caused the mind and the body to be coordinated. This is also not as strange an idea as it seems at first. The formal structure of the world informs both the form of the body and the form of the language/mind.
I continue to think that there are no "representations" in the brain, and that intentional predicates are made of whole persons, not brains. But my appreciation of Fodor has deepened. The main problem I have with Fodor is that his arguments have been so extensively elaborated (by him!) that they are a kind of rabbit whole; one either writes a book on Fodor, or leaves him alone.