So, if you're starting out with a question, what kinds of things are there? What kinds of things exist? Then, there are two primary answers to that question. One of which is known as monism, the answer namely is one kind of thing. The other which is known as dualism, the answer there are two kinds of things. Standardly, monism could take either one or two forms, the most popular being, what's known as materialistic monism. That is that everything that exists is matter or some force or property of matter. And if you're a materialist monist you'll say, even people are purely physical things, even their thoughts are purely physical processes. You could also be a monist by holding that everything in a sense is mental but the only things that exist are in some sense ideas that's if we associate with the philosopher George Berkeley, not something that we'll be trying to defend here or explain here, but there is a version of monist that says everything is as it were ideal as opposed to material. Whereas on the other side is the dualistic position which says that there are two kinds of things and a purely physical description of the universe will never be a complete description. If you're a dualist you're going have to worry about a couple of different questions. As I adumbrated before, common sense seems to show that as an everyday occurrence, mental events can bring about physical changes and likewise in the other direction. But if you're a dualist, it's not quite clear how that interface is going to go. Descartes did a fair bit of vivisection, that is operating on animals, not all of whom were dead at the time. He always did a lot of dissection of human corpses and he found inside human brains what we now know to be a genuine part of the brain that's now referred to as the pineal gland. And he thought that maybe the pineal gland is the locus, the place at which mind and body interact. But claiming that mind and body interact at the pineal gland or at any other place, just raises all those old questions over again. How do those things interact? According to the principle of the causal closure of the physical, every physical event that has a cause, so we are going to have to assume that every physical event does have a cause. But every physical event that does have a cause has a purely physical cause. That seems to be a pretty deep presupposition of modern physics for example, but if you're a dualist, you're going to have to deny that. Because if you're a dualist, you're going to have to say that there are mental events that are not identical with any physical events that bring about physical changes. And that would seem to be a violation of the principle of the causal closure of the physical. So, one consequence that should make a dualist scratch your head and wonder what's going on, is the fact that the dualist seems to fly in the face of both the common sense, fact the mind-body seem to interact, and the fact that seems like it's a deep part of physics that the physical world is causally closed. They seem to have to run against those two, it seems facts and if you're not going to run against them you'll have some explaining to do. Likewise, it seems like if you're a dualist a mystery arises as to how it is we could know about somebody else's mind. If dualism is right then we know about our own minds in an introspective way that seems to produce a high degree of confidence but how do I know about what's happening in somebody else's mind? Common sense suggests that on an everyday basis, especially for those people that I have lots of interaction with, I can often know what's going on inside of their mind, I can tell by this person's furrowed brow that she's irritated. I can tell by that person's continuing to fidget with their hair that they're distracted or that they're angry. But if you're a dualist in the tradition of Descartes, that's going to be a mystery and in particular, there's never going to be any way of finding out for sure what's going on in somebody's mind because even if you were to open up their cranium and look inside their brain, you would never be able to get any conclusive evidence of what's happening with them mentally. Whereas, if you're a materialist you at least have hope that that sort of thing could be established beyond a shadow of a doubt. So, those are not absolute reputations of dualism, they're things rather that raised questions for dualistic position that the defender of that position is going to have to say more about to either explain them, explain them away etc. Final point I want to make about Descartes and his project for now is the following: whereas with Socrates and his interlocutors, we found that learning about oneself, knowing about oneself had to do not just with knowledge but to some extent also brought in the notion of wisdom. That is to say, being wise when we try to figure out what it means, what the Delphic Oracle meant in saying that no one is wiser than Socrates, involved not just knowledge about oneself but knowledge of one's limitations, one's ignorance and thereby why what we thought was what made that valuable and made Socrates to have a bit of an edge over many of his fellow Athenians was that by virtue of being aware of his limitations, he was more likely to be able to act wisely not act foolishly, not hastily interpret things that the Oracle said and thereby go into battle and have his empire destroyed for example. Whereas Descartes says not very much about wisdom, at least in the writings that we've looked at, but mostly about knowledge. Where and we often notice that one could have a lot of knowledge without necessarily being wise. So, there's not an obvious connection between Descartes notion of self knowledge and Socrates. Socrates gives us a notion that perhaps in some ways is more satisfying because it has to do with the wisdom not just knowledge. At the same time however, Descartes gives us a method that he hopes will be rigorous, as a way of helping us move out of our knowledge of ourselves to knowledge of the external world in ways could bound up with the rigorization of modern mathematics and modern science. And also as a powerful argument for that helps us answer the question what is the relationship between the mind and the body? Either we're going to accept that with its consequent puzzles or we'll have to find a way in which Descartes might have been mistaken and that's a set of questions of what we'll move onto in our next lecture.
