A final passage from Christian List

List criticizes the "causal exclusion" argument, which is a recent formulation of the case for epiphenomenalism in mind-body relations.

By usual definition,"epiphenomenalism" is the view that though there is an intangible mind distinct from the body (there are such things as "intentions" for example, which may not be reducible to any physical sort of fact), this mind, these intentions DO NO WORK. They do not function as causes, just as the steam coming out of a train does nothing to move the train.

The causal exclusion argument works from two premises:

1) the premise of the causal closure of the world. Any physically realized event has a sufficient physical cause.

2) the premise of causal exclusion. If an event has a sufficient cause, then it has no other distinct cause at the same time.

I'm standing outside on the street and a cab comes by. I raise my arm in a familiar gesture. Why did I raise my arm? The first premise tells me that there must be a sufficient physical cause (which we may think of as the firings of various neurons). The second premise tells me that once I have found this physical cause, it will be the only cause.  Thus, whatever non-physical facts may exist, they have no work to do.

QED.

List argues against this view. He maintains that the problem is the word "sufficient" in both premises. He believes that word is ambiguous and that, however it is understood, one or the other of the premises is false.

On the way to that response, though, he says various intriguing things. One is that IF the argument is valid, it would have to be applied much more broadly than merely to establish epiphenomenalism of the mind. If would also establish the epiphenomenalism of biological phenomena (the efficacy of which would be excluded by the causal sufficiency of chemical explanations) and then the epiphenomenalism of chemical phenomena (the efficacy of which would e excluded by the causal sufficiency of explanations from fundamental physics).  So there would have to be some bottom turtle -- say, explanation by quarks, or by "strings" that make up quarks.

Yet, at such a level, "cause" seems to disappear, as must the causal exclusion premise. Here, at last, the promised final quote of our three-post survey of Dr List's work.

"In particular, the ideas of cause and effect do not seem to have much of a place in current fundamental physics. In the sciences, cause and effect reasoning is much more common in the special sciences, such as biomedical, human, and social sciences, than in fundamental physics, like classical and quantum mechanics. The causal exclusion argument would therefore cause us to look for causal relations at a level at which such relations are least likely to be found."

p. 126.