Meaning and Mental Representation Chapter 5

Fodor's causal theory: "A symbol expresses a property if it's nomologically necessary that all and only instances of the property cause tokenings of the symbol."
2 problems with this theory, one stemming from the "only" clause [the disjunction problem] and one stemming from the "all" clause.
(1) The problem with saying that it's necessary that only instances of the property cause tokenings of the symbol is that some noncats cause |cat|s. Once again, this is the problem of misrepresentation.
Fodor proposes a solution based on the following asymmetrical dependence:
(i) If mice didn't cause |mouse|s, shrews wouldn't cause |mouse|s.
(ii) If shrews didn't cause |mouse|s, mice wouldn't cause |mouse|s.
The asymmetrical dependence of shrews on mice lies in the fact that (i) is true, but (ii) is false.
However, is (ii) false? After all, if shrews didn't cause |mouse|s, it might be because mouse-looks didn't cause |mouse|s, in which case mice wouldn't cause |mouse|s either. This leads us to the objection that there is no single interpretation that makes (i) true and (ii) false. For there are two ways to break the shrew-to-|mouse| connection, and two ways to break the mouse-to-|mouse| connection. If mousey looks don't cause |mouse|s, then both (i) and (ii) are true. If mousey looks do cause |mouse|s, but mice don't cause mousey looks, this won't affect the shrew-to-|mouse| connection, so both (i) and (ii) are false.

(2) The problem with saying that it is necessary that all instances of the property cause tokenings of the symbol is that not all cats cause |cat|s. Why do we want to say that it is all instances? Because if some cats don't cause |s|s, then the extension of |s| should be the subset of cats that do cause |s|s. So we need genuine covariation- all cats cause |s|s (or, any cat would cause an |s| if given a fair chance). But what is it to be given a fair chance? This leads us to a problem of circularity similar to the one we saw in chapter 4 [where Cummins concluded that Lockeans must specify ideal conditions in a way that does not presuppose content assignments to states of the cognitive system]: If covariance is grounded in a mechanism that, under the right conditions, will produce a |cat| from a cat, and, according to the CTC, the mechanism in question can be understood only by appeal to inner representations, then in order to understand the mechanism that CTC invokes to explain covariance between cats and |cat|s we must already understand representation and the explanatory role it plays in mental mechanisms.