Arguments against mind-body dualism

 

Someone asked at Quora for the best arguments against mind-body dualism. The following is a (slight) re-working of my response there. 

The Quorant was not specific about whether he meant "substance dualism" or "property dualism". I will note for the record then, that property dualism was created in part as an answer to some of the standard objections of substance dualism. 

I won't define those terms further now, though, because to my own mind there are two powerful arguments that must be rebutted by advocates of EITHER of the dualisms.  These are what I will discuss right now: the argument from evolutionary continuity and that from neurophysiology.

First, continuity. If one accepts the broad biological model that the human species has its origin in random variation from other primates, and the primate genus has its origin in random variations from non-primate mammals, etc. AND if one believes humans are distinctive in having a mind in principle distinct from a brain, an obvious question arises. HOW are we distinct? WHEN did we become distinct? Did some simian ancestor stand on his/her legs and then a light internal to the skull turned on: a light that had been off since the beginning of time? All of a sudden there was an internal light? Perhaps in the presence of a mysterious monolith? 

Perhaps you think it is “to consider too curiously to consider so.” Nor do you solve the problem by letting the dividing line slide. Include ALL primates as creatures with a mind, if you like. Or all mammals even. Why and how did the light turn on when it did? Why is any such line drawing not arbitrary?

Second, neuroscience. Until, say, the 1890s one could make the argument that mind events are not CAUSED by brain events, that they are only CORRELATED with brain events. Maybe electrical activity in a certain neuron always increases when I think about the possibility of winning the lottery. That does not mean that the brain activity IS my idea of the desirability of such a win. So far we can only say that the two facts are correlated. And dualistic argumentation can build on that presupposition. 

BUT [to get to the promised argument against dualism] for well over a century now evidence has been building up that there is indeed causation, and one can make a case that the cause-effect arrow runs in only one direction. The electric activity is the cause of whatever I may report about such ideas. I don’t review such evidence for now — there are plenty of sources for such arguments if you want to pursue them. 

Anyway, if they are not all misleading, then one can reasonably argue that we are left with, at most, a subjective side of what are in every effective sense physical FACTS. “I bought the lottery ticket because I hoped for winnings” turns out just to mean, “Certain electrical activity in my head caused my body to walk into a grocery store, hand over to the clerk a dollar bill, and speak the necessary words to get a lottery ticket.” Or whatever the best physicalist rendering might be. Also, "as I acted thus I felt a subjective sensation that I call 'hope'." But that last bit doesn't matter, does it? 

Personally, I am a dualist of an emergentist sort. So I believe these arguments can be overcome — a plausible case for the development of mind (even considered as a substance -- a sometimes-effective ghost in the machine) within evolutionary time can be developed and it can be said to have an effective role in our lives now. But you [Quorant]  didn’t ask for my views. The above should answer the question you did ask.