I’ve been working on a response to Plantinga’s Evolutionary Argument Against Naturalism, which has me reading the newest iteration of the argument in his book with Michael Tooley, Knowledge of God. In it, another argument against naturalism got my attention. A neural event will have NP properties (the physiological properties of the neural event), and content (the proposition itself: ‘There is a sabertooth tiger in the bushes’). Given a naturalism account of thought and conscious activity, it seems we have a neural event that is causally and logically sufficient for our propositional attitudes. So my NP properties are logically and casually sufficient for my belief that ‘My argyle socks look awesome.’ According to naturalism, we need not countenance an immterial self/soul that thinks those things, because our NP properties are sufficient.
Plantinga feels that it’s impossible to imagine/conceive of a way in which an “underlying reality” (that is, the NP properties/neural event itself) can account for thought. He notes possibly the most well-known appreciation of this problem with Leibniz:
“One is obliged to admit that perception and what depends upon it is inexplicable on mechanical principles, that is, by figures and motions. In imagining that there is a machine whose constructionwould enable it to think, to sense, and to have perception, one could conceive it enlarged while retaining the same proportions, so that one could enter into it, just like into a windmill. Supposing this, one should, when visiting within it, find only parts pushing one another, and never anything by which to explain a perception. Thus it is in the simple substance, and not in the composite or in the machine, that one must look for perception.” (SEP)
I’m rather nonplussed by the prospect of using our imagination or ability to conceive as a means of determining reality. When I was younger, I had no idea how microwaves worked, and I thought the lights inside must be incredibly hot to warm up my Hot Pocket so quickly. I was always baffled when I opened the microwave and found that the air wasn’t exceptionally warm and the lights weren’t even remotely hot. How did it cool down so quickly? Does my inability to conceive of how a microwave works have any bearing on the reality of the microwave working? Assuredly not.
Let’s examine Plantinga’s proposed solution. Pretend for a moment that Leibniz’ Mill is an insurmountable problem and it seems we need to countenance an immaterial self to properly capture the phenomena of thought. Peter van Inwagen points out the difficulties inherent with either account: why should it be any easier to explain thought via dualism (immaterial parts maneuvering to form thought) than it should for materialism (material parts maneuvering to form thought)?
Plantinga argues that they are different because typically an immaterial self, a soul, is simple. It does not consist of parts, therefore thought does not need to be explained by the workings of its parts. One might ask, how does it produce thought? It produces thought because it is a basic activity of selves to think. Just as an electron has a charge, immaterial selves have thought. Therefore, asking the question How does an immaterial self think? is just as nonsensical as asking How does an electron have a charge?
It is harder for me to imagine an immaterial thing that thinks basically than it is to imagine a combination of parts generating thought. It prompts a laundry list of questions: How is thought properly basic to an immaterial self? How can an immaterial thing think, and do we have good evidence for thinking that they do? How can an immaterial self have parts or not have parts? Where does the immaterial self causally interact with the material self? The pineal gland?
It seems to me that this is just another ghost in the machine (a la Ryle), and does very little in moving forward sensical talk about the process of thought. The inability to imagine or conceive of a system producing thought has no bearing on whether it actually can.