From PhilPapers forum Philosophy of Mind:

2009-05-18
The 'Explanatory Gap'
Reply to Arnold Trehub

MAKING COMMON CAUSE


AT: "Your conclusion is wrong because you appear to be endorsing each of the following propositions:
-- (a) All brain states have causal consequences.
-- (b) Feelings are brain states.
-- (c) Feelings have no causal consequences.
"Given (b), proposition (c) is contradicted by proposition (a)."
Here is a sure way to know that one has either cheated, trivialized, or otherwise begged the question in the way one has formulated the problem: if one's formulation would apply unproblematically and indifferently to any old brain property at all. "All brain states have causal consequences - X is a brain state - So X has causal consequences - No problem" then there is a problem with one's formulation of the problem.

The problem is that when "X" happens to be feeling, it is not at all evident what we are saying when we say "feeling is a brain state." Behavior, for example, is not a brain state, though it is caused by brain states. ("State" is a weasel-word, covertly doing double-duty here.)

So let as assume (since it is surely true) that brain states cause feelings, just as they cause behavior (even though we can explain how and why brain states cause behavior, but we cannot explain how and why they cause feelings).

Now with behavior -- which, to repeat, is not a brain state, but is caused by brain states, with no problem at all about explaining why and how it is caused -- there is also no problem with the consequences of what the brain state causes, in causing behavior. Behavior itself has its own consequences: My brain, with the help of a slippery pavement, causes me to stumble; I fall on your cake; the cake is squashed; you send me the bill.

But with feeling -- which, to repeat, is not a brain state, but is caused by brain states, inexplicably [that's the first part of the problem, and hence of the explanatory gap] -- there is indeed a problem, an even greater problem, with the consequences of what the brain causes, in causing feeling. For feeling does not have (and cannot have -- on pain of telekinetic dualism) any independent causal consequences of its own: My brain, with the help of a slippery pavement causes me to stumble (though I feel I tried everything I could to keep my balance); I fall on your cake (I feel clumsy); the cake is squashed (I feel embarrassed; you feel angry); you send me the bill. (I pay it, because I feel I should) etc.

So, to reformulate your scenario without begging the question:

-- (a) All brain states have causal consequences.
-- (b) Feelings are (unexplained) causal consequences of brain states.
-- (c) Feelings have no causal consequences: 
-- (d) What we feel to be causal consequences of feelings are really the causal consequences of the brain states that (also, inexplicably) cause the feelings.

Given (d), proposition (c) is perfectly consistent with propositions (a) and (b).

Common causes (functing) can have multiple correlated effects, and in the case of behavior (functing) and feeling, the feeling has no independent (i.e., non-telekinetic) effect, it just dangles, inexplicably.

The explanatory gap (which cannot be closed by a series of non-explanatory propositions presupposing the solution of non-existence of the "hard" problem.).

-- SH