We begin with some quotations from Fodor.
[I]t is crucial to the whole program of explaining behavior by reference to mental states that the propositional attitudes belonging to these [causal] chains are typically non-arbitrarily related in respect to their content (taking ``content'' of a propositional attitude, informally, to be whatever it is that the complement of the corresponding PA-ascribing sentence expresses). One can imagine the occurrence of causal chains of mental states which are not otherwise related (as, e.g., a thought that two is a prime number, causing a desire for tea...)...Still if all our mental life were like this, it's hard to see what point ascriptions of contents to mental states would have...The paradigm situation--the grist for the cognitivist's mill--is the one where the propositional attitudes interact causally and do so in virtue of their content. And the paradigm of this paradigm is the practical syllogism...John believes that it will rain if he washes his car. John wants it to rain. So John acts in a manner intended to be a car-washing...Our common-sense psychological generalizations relate mental states in virtue of their content...(Propositional Attitudes, as published in Representations, pp.182-184)
I dearly wish that I could leave this topic here, because it would be very convenient to be able to say, without qualification, what I strongly implied above: the opaque readings of propositional attitude ascriptions tell us how people represent the objects of their propositional attitudes...(Methodological Solipsism, Representations, p. 236)
What I think is exactly right is that the construal of propositional attitudes which such a psychology renders is nontransparent...The trouble is that nontransparency isn't quite the same notion as opacity, as we shall now see. (ibid, p. 236)
Having said all this, I now propose largely to ignore it...( ibid, p. 239)