withallyourmind.net

One of my philosophical interests is the philosophy of mind, especially consciousness and the dualism/physicalism debate. By ‘interest,’ I mean something that I would someday like to study in depth and be knowledgeable about. I have also just finished reading through Peter van Inwagen’s Metaphysics, in which he dedicates two chapters to the debate between dualists and physicalists. Although van Inwagen is a Christian, he is also a physicalist and he gives several arguments against dualism that he thinks favor physicalism. These got me thinking about a couple of options to which dualists could appeal to answer the most common arguments against dualism, but to which they rarely do. Of course, it may just be that because I have done so little reading in this area, I am simply unaware either of the total number of people who do appeal to these or of some obvious reasons these won’t work. Nevertheless, they seem reasonable enough to me to at least merit further discussion.

Anyone who has done any philosophy knows that dualism is obviously false because of the question of interaction - How could something non-material causally interact with something material? Of course, such a simple question is not an argument, but this is about all one is usually likely to find on the interaction problem. One philosopher who has tried to make explicit what the interaction problem actually is is Jaegwon Kim. His argument, greatly simplified, is that in order for a causal relation to hold between two things, there must be some relation that “pairs” them, and that this “pairing relation” is necessarily spacial. Since immaterial souls have no spacial location, they cannot be relata of a pairing relation, and therefore cannot be relata of a causal relation.

I’m not sure what to think of this pairing relation, but granted that Kim’s argument is sound, one option for the dualist is to deny that souls have no spacial location. There does not seem (to me anyway) to be anything incoherent about supposing that something can be both immaterial and in space. Think of our folk ideas about ghosts and disembodied existence. A promising option for the dualist, then, might be to claim that the immaterial soul can interact with its material body precisely because they occupy exactly the same space (or perhaps the soul occupies exactly the same space as the brain - hence G.E. Moore’s claim “I’m closer to my head than to my feet”). This is something I plan to spend some time thinking about eventually. (See this post by Andrew Bailey for a more indepth treatment of this topic).

The argument that van Inwagen finds most persuasive against dualism is based on a thought experiment about a duplicating machine. This machine is one that can make exact physical duplicates of anything that is put into it. Suppose that a man, Abob, walked into this machine and beside him appears an exact physical duplicate of Abob as he was a few seconds ago. Our intuitions about this duplicate indicate that we would expect him to be fully functional, having all of the same memories, beliefs, and intelligence of Abob. We would expect the duplicate to think himself to be Abob, and to go on to enjoy exactly the same type of varied mental and conscious life that Abob is able to experience. But these intuitions, according to van Inwagen, count against dualism. If all that the machine did was make an exact physical copy of Abob, then presumably his soul wasn’t copied. But if no soul was copied into the duplicate, how could the duplicate have the conscious experience and mental life that we expect him to have? The only options for the dualist appear to be to either deny that the duplicate would have any conscious mental life, or to go to the extreme to claim that whenever a fully formed human body comes into existence, God instantaneously creates a soul to go along with it.

An option not discussed by van Inwagen is to claim that the soul is not something directly created by God, but something that emerges from particular highly complex arrangements of matter. Presumably, God would have had to build this capability into matter during creation. Emergence is something that is being hotly discussed by philosophers these days, and many think there are metaphysical problems for any sort of strong emergence. I do not know enough about these difficulties to comment here. However, the approach seems promising and even intuitive to me, and if emergence of any kind is possible, it isn’t obvious that a different type of substance could emerge. Some dualists who are theists (are there any who aren’t?) might have theological problems with this view, and it may be tricky to reconcile it with life after death. Nevertheless, if the soul is something that emerges from certain complex arrangements of matter, that would explain why Abob’s duplicate was conscious, as well as explain how it is that humans came to be conscious - at some point during evolution, our ancestors reached the right state of physical complexity to give rise to souls (assuming both that evolution occurred and that human beings are the products of evolution (which I have tentatively come to accept)).

There are some things that would need to be worked out with both of these options, but, as I said earlier, they seem at least initially reasonable and worth some further consideration.