Okay, well here we go. We're ready to go with chapter four. We finished chapter three, if you recall, talking about the problem of universals. And we saw that Galileo had proposed a particular approach to this, where he distinguished the nature of two kinds of things. Primary qualities, which are descriptive of things, of objects, and secondary qualities, which are ways of describing our perceptual experience and our consciousness of those.
of those primary qualities. So primary and secondary being very distinct from each other in a qualitative way. What we also understood from that is that that was dualism. And that's nothing new for us because we've been, all the way back to the Greeks, we've been talking about dualism.
Now that we're going to get a little bit more modern, we can also talk about perhaps the most famous. of all the dualist philosophers with the French philosopher Descartes. And one of the things that you might also think about when you think about all the classic dualism that we talked about amongst the Greeks, is that dualism and rationalism tended to go hand in hand.
If you notice that a lot of the Greek rationalists, Plato, Parmenides, Pythagoras, they were all dualists too, because they all said that you can't trust the senses. And one of the reasons that they don't trust the senses is because they keep saying that the senses are not telling us things that are real. They're not telling us about reality. And anytime you have this claim that appearance is not the same as reality, then that's dualism, right? And Descartes is going to say a lot of the same things here, though he does it in a slightly different way.
So we have what we call a thought experiment. the brain in a vat thought experiment. What's a thought experiment? Well, when you want to do an experiment, you can actually conduct the experiment, but if you don't actually have the capability of conducting the experiment, then you can just imagine doing the experiment and think about it, and then it becomes a thought experiment.
So his thought experiment is to, he asks us to imagine that we could have a brain in a vat, so it's so much so good we could do that, but that we would also be able to somehow artificially simulate signals through its various sensory inputs, its nerves, to create patterns that could perhaps otherwise simulate the kinds of sensory patterns that would come from this brain not being in a vat, but actually being in a body, and that this body could be in a place, could be in a room somewhere, seeing things. And so this would entail a pretty advanced technology. Descartes envisions the possibility of some sort of all-powerful evil demon or evil scientist who wanted to deceive and convince this brain, this consciousness inside the brain, that it was not just a brain in a vat, but that it was a brain in a body doing something. And what we're left with, of course, is Descartes concludes that If this was the case, if this was possible, one question we could ask is, would the brain, the person in the brain, the consciousness in the brain, would they know it? Would they be able to understand that the experiences that they were having were not real and that it was just a deception?
And Descartes'conclusion is that this consciousness would not be able to do so. Which of course then raises the question of whether or not this applies to any one of us. How do we know that we're not brains and vats? How do we know that we're not experiencing a reality, a body and a reality that is completely illusion? It's deception.
It's false. Now, right off the bat, we can see that he's making this claim very much like the Greeks that... this is going to cause us to not want to trust our senses, right?
So if we don't think the senses could be telling us the truth, that it could be false, then we discard sensory knowledge and we adopt rationalism. But one of the other major goals of Descartes here was to try to create a philosophy based on claims that could not be doubted. And part of the issue, of course, is that we saw so many of the different philosophies emerging from the Greeks.
contradicting each other. And maybe some of the problems with all of these contradictions is that all of those old philosophies rest on assumptions that perhaps were problematic and perhaps could be doubted. And Descartes says, maybe it would be better if we could come up with a philosophy where my starting assumption is one that cannot be doubted. And so his real point here was to come up with this famous undoubtable statement.
And that is his, I think, therefore I am. So we could doubt the senses, but we cannot doubt the fact that I am here having these thoughts in the first place. place, that I am engaging in the act of doubting and thinking. And so even though I could doubt my body and I could doubt the world around me, I cannot doubt my own mind.
I cannot doubt my own consciousness. It must exist. Though, got another ism here.
We could think about the possibility that if we really went to the extreme here, then this could entail the possibility. that my consciousness, which I cannot doubt is real, is the only consciousness that exists in the universe. That my body doesn't exist, the house that I'm in doesn't exist, all of the students that I think and I'm talking to through my computer here do not exist. It's all false, it's all an illusion, perhaps a deception because of some evil demon or evil scientist who wants to deceive me. This is called solipsism.
The idea is that if we really take these ideas seriously, maybe there is no other consciousness in the universe besides my own. Now, Descartes never intended for us to go that far with this kind of thought process here. He really just wanted us to realize that it would be possible to doubt the senses, but to not actually doubt the senses, right? So, So he's going to be a rationalist. He's going to say, yes, thinking, logical thought, all of that internal stuff, that's important.
That's the key to knowledge, not the senses. But he doesn't want us to go down that slippery slope of solipsism. That does remain a logical possibility if we were to really take this thought experiment seriously. So like... Those others before him, Descartes is both a rationalist and a dualist.
Descartes is really one of the first philosophers to really bring the concept of dualism to the fore and make it explicit that this is what we're talking about here, that there are these two realities. We see that the kind of dualism that we talked about in the Greek philosophers, it was really more implicit in what they were describing. Descartes is really, really explicitly espousing the idea that mind and body are somehow different from each other, and that there would be two different things, right? And now they need to interact with each other. And so this is a tricky thing, right?
How is it that a thought, how do I have a thought that I want to do something like scratch my face? So of course, the idea is that that causes my hand to come up here and scratches my face, right? So the mind controlled my arm. This is not a one-way street of communication, though. There's back and forth here, because now what happens is that the hand coming up here and scratching my face, that's a physical bodily process, but it activates sensory receptors, travels back into the brain and back into the mind, which then provides that kind of feedback to tell the mind the consequences of what just happened.
Oh, I felt an itch. I want to scratch it. So now it succeeded. It's gone, right?
So this back and forth, the mind tells the body what to do, the body informs the mind that those actions were performed successfully. So that's the nature of interactionism, mind-body interaction. How is this achieved? Descartes, since we're talking about dualism here, that mind and body are somehow different from each other, the first step in this kind of theory is to actually define what we even mean in the first place by mind.
and also define body and other physical things. So we need to have a definition of what is the stuff of mind, what is it made of, and what is the stuff of body, and what is it made of, what are the particular qualities of these two substances? Well, we have that conveniently mapped out right here in these five corresponding points here.
So our first definition, the mind is non-spatial but the body is three-dimensional, which means spatial, right? What does it mean to say that the mind is non-spatial? Let's contrast it first with the body.
We say it's three-dimensional, right? So we can say a three-dimensional object is something that has a length, a width, and a height, right? But we can also think about it as, well, we've previously talked about way back in chapter two, one of those philosophers was also a mathematician, Pythagoras, right? You learn about Pythagoras in geometry and trigonometry classes because of his theorem that tells us how to calculate the length of the hypotenuse of a right triangle, right? But you learned about Descartes in high school math as well.
because you learned about the Cartesian coordinate system, which is named for him. He invented analytic geometry, and it gives us a way in which we could talk about defining positions in space, right? You learn it just in terms of making graphs, right? You have a graph with an x-axis and a y-axis. You can assign coordinates x and y.
So in reality, Descartes is talking about a three-dimensional space, so you can also try to graph that, an x, y, z coordinate system, and assign... things, positions, x, y, and z in that three-dimensional space. So of course the body being three-dimensional means it can be assigned positions in this three-dimensional space.
It can be given x, y, z coordinates. The mind, on the other hand, if it's defined as non-spatial, means that it cannot be spatial. It cannot occupy a position in that space.
It cannot be given coordinates. Next point. These two points are basically just opposites of each other, and very much the first points are, right?
Spatial versus non-spatial. Here, material for the body, immaterial for the mind. M means not, right? So it's not material. So material means that we're talking about the body made of material substance.
Whether we're talking about the old-fashioned idea of atoms from Democritus or the more modern idea of atoms, whatever substantial theory you want to talk about of matter, that's what the body is. The mind is essentially not that immaterial. What do we mean by immaterial as being not matter?
It's ghostly, right? It's ethereal. It's not a substantial thing.
The best analogy I can come up with would be something like Casper the Friendly Ghost, right? Casper the Friendly Ghost can walk through walls because the walls are made of matter, but Casper is not. Casper is immaterial, cannot interact with matter, which... is a red flag for us, right? Because if the mind is like the ghost in the machine, as we have come to know the concept behind Descartes'ideas here, how does the mind in this way interact with matter at all?
We also see that the body is determined, but the mind has free will. Of course, this makes some sense that if the body is material, it must obey the laws of matter, the laws of physics govern it. But the mind, being immaterial, would be exempt from the laws of physics and can have free will.
In a claim that kind of harkens back to the Greeks here, we see that the mind is perfect and the body is imperfect. That's a very platonic way of thinking about things. And in this very interesting contrast at the bottom, the mind is the realm of truth, reason, and wisdom, but the body is the realm of action.
How are those opposites of each other? Are they meant to be opposites, or are they just distinctions? Well, one way we might think of them as opposites of each other is if we remember Parmenides.
Remember Parmenides saying things, and Zeno has done it in the various paradoxes, like the dichotomy paradox, that motion is somehow illogical. violates the logic of mathematics. And so maybe it is the case that, you know, that the wisdom and the reason and the logic that happens in the mind is somehow incompatible with the actions of the body.
So now that we have this two substance theory, the mind is defined as it is, the body defined in very much the opposite. We still need a way of explaining how these two different things can interact with each other. So we get his interactionist theory, and it's called mechanistic interaction because, well, I've suggested that Descartes, one way to call it is the ghost in the machine, right?
It's down here at the bottom of the slide. That's really a 20th century term. So it wasn't something that Descartes was using, but it... very aptly characterizes the basic idea. Descartes was inspired actually by watching these these mechanical statues.
So an artist had created these statues of ducks that could move around. So the statues actually had articulated limbs, the wings, the legs, the head and neck could move based on various articulated joints. And there was a mechanism to control the movement based on hydraulics, right? So there were water pipes that would flow through the joints, inflating. bladders in the joints.
And so the ducks could flap their wings because you could push water at high pressure into those bladders and cause the wings to move up and then drain the water out, and the wings would go down. And so you get this simple little hydraulic mechanism that could create coordinated movements, at least in these statues. But what about bodies? Well, Descartes In addition to all of the other stuff that he's doing, he was also an anatomist.
He studied animals and human bodies and nervous systems. And he had observed some things, such as the fact that the ventricles of the brain are filled with fluid. We know it to be cerebrospinal fluid.
He called it animal spirits, which we don't, that's a confusing term. It doesn't mean spirit in the spiritual, you know, soul kind of thing, the way Plato was talking about. It means like a special fluid, like distilled spirits or liquor, right? So a special fluid in the brain that fills up the hollow ventricles.
But he also, of course, observed that the spinal cord also has a hollow pore down the middle of it, and these fluid, the animal spirits, flows down into the spine. He then speculated that maybe even the peripheral nerves that branch off of the spine also contain a small pore down the middle, and that, therefore, These animal spirits are flowing through the entire nervous system. It's basically just a series of tubes and maybe it's hydraulics, right?
Just like water passing at high pressure through the pipes of these statues could cause the statues to move around. Here, the animal spirits flowing through all of the various nerves could cause the similar kind of thing that animal spirits would flow into your arm and inflate the muscles like bladders, which would then cause movements around the... the articulations of your elbow and shoulder and wrist and so forth.
Of course, he's a little bit wrong there because even though it is true that there's cerebrospinal fluid in the ventricles of the brain and in the center of the spine, the rest of the peripheral nerves do not in fact have a pore down the middle where you could have this fluid flowing through them. But he at least starts with this idea that this is the way bodies work. that there's some kind of a process of flowing from the brain into the nerves.
And just at a simple way of describing it, that, of course, is still consistent with our modern neuroscience. Instead of animal spirits and hydraulics, we would just talk about action potentials, but it's still, therefore, a chain reaction of things coming from the brain down to the spine and out to the peripheral nerves. But we still need something that initiates this process.
What actually causes the flow of the animal spirits or, in modern neuroscience, the action potentials? to go from the brain down to the peripheral nervous system. Well, in Descartes'sense, of course, this is supposed to be the mind, right? But where does the mind get involved?
How does it get involved? How could it actually cause this to happen? This is where we get the pineal gland business from Descartes here. So Descartes remarks on his anatomical studies of human brains that the pineal gland appears to occupy a very special position, that it's...
centered at the base of the brain, making it somehow important based on its location. He also remarks that unlike the rest of the brain, which seems to have two halves to everything, right, the cortex has left and right hemisphere, the thalamus, the cerebellum, all those various parts of the brain have left and right halves, but he said that the pineal gland was more of a singular organ that did not have a left and right half. He thought that was special. He was actually wrong about that.
The problem is that you need a microscope to really be able to see the left-right division of the pineal gland. But he thought that was special. He also made another mistake, which is that he thought that animals did not have pineal glands.
It's actually pretty small, and so it's difficult to find with humans in the first place. But on an animal brain, it's very difficult to find. So he had incorrectly assumed that this was a part of the brain that was not only unique and special in terms of its singular organization, as well as in its special place at the base of the brain, but that it was something that was only found attached to human brains.
It's worth pointing out that Descartes, back up here to our definition of the mind, does not believe that animals have minds. And he does not believe that animals have free will or reason and logic and so forth. In that case, it would make a lot of sense for him to suggest that maybe the pineal gland is the so-called seat of consciousness or seat of the soul or the ghost in the machine, right?
It's where the mind exists inside the brain. And now we're going to do that. We still have to find a way in which the pineal gland can trigger the flow of these animal spirits.
So inside the pineal gland, it's allowed to make tiny movements. And these very tiny movements are amplified. through hydraulic action.
So just like the brakes in your car amplify the action of your foot on the brake pedal to cause enough pressure to actually stop your car, the same thing would be happening here that these tiny movements of the pineal gland are enough to cause much larger movements of your arms and legs because that's the nature of hydraulic action. It can amplify all of that work. But we might see that there's some issues here. Right? One of the issues is that how is the pineal gland or the mind allowed to reside inside the pineal gland?
Let's come back to our list of definitions of mental things here. If we're going to localize the mind inside the pineal gland, that means we have given it a location, a position in space that violates our very first point. Right?
We're also now suggesting that inside the pineal gland, it's going to move. Movement violates, again, the first point, because movement in the Cartesian geometry is defined as a change in position. Right?
A change from one coordinate, x, y, z, to another x, y, z coordinate. But if the mind cannot be assigned coordinates, then it cannot move. And that's also what we're talking about on our fifth and final list here, is that Yes, reason and truth are the opposites of action. The mind should not be able to move.
The body can move, but not the mind. So how is it making these small movements inside the pineal gland? Maybe it's because they're tiny movements, that that somehow makes it okay because it's so tiny, it's like they're so small it doesn't really matter. It's not really a movement. But...
Technically it's supposed to be a movement, right? So it's really a violation. Not to mention, of course, the idea is that if something's going to move and cause, which then causes something else to move, we have to understand the physics of that. We have to go to something like Newton's second law of motion, force equals mass times acceleration. So in order to cause a mass to accelerate, you have to apply a force to it.
But that force has to come from another mass, right? It has to come from another moving object. So This is why Caspar the Friendly Ghost cannot move an object, because he cannot impart force onto another object, because he has no mass, he has no material substance.
So in order for this to also make sense, we have to also, coming back here, violate the second point. The mind has now been materialized, as well as localized, inside the pineal gland. And of course it's moving.
We've violated at least three of our five definitions of mind. in order to make this idea work. So we have a problem, right?
This kind of mind-body dualistic interaction simply cannot work unless we're going to actually abandon our definition of mind and give it a definition that it's no longer dualistic at all. It instead becomes materialistic monism. It takes some time, though, for philosophers to really come around to recognizing.
This is not going to work at all. Descartes does not acknowledge that his theory is a violation of his own definitions, right? And even other philosophers, as we now jump into some others here, they recognize that there are some problems with the nature of Descartes'mind-body interactionist theory. But in their view, the problem is not dualism, right? Dualism has been around at this point for centuries, and it's not something that they're just going to reject quite so easily.
So Spinoza, for example, is going to come up with another theory that tries to deal with the problem of dualism, but without getting rid of it entirely. So he's going to... what he's going to get rid of really is the interaction side of it. So his approach is called double aspectism. And so we are asked to think of the mind and body as being two aspects of the same thing, right?
Just like two sides of the same coin. Think about what that means, right? You can have a coin, you have a head side and a tail side.
So they're obviously distinct and different from each other. But nevertheless, they're part of the same underlying thing. So that would be a single substance theory, right? But in this case, mind and body being... part of the same underlying reality.
It's not a coin. It's, what is it? Well, Spinoza is a very highly spiritual guy.
So he says that everything is God, that that single substance that makes up everything, mind and body and everything is God. In fact, everything in the world is made of God. Not just you and your mind and your body, but the table, chair you're sitting on, the grass in your yard, everything, your best friend and your enemy, everyone. We're all, everything is made of God.
This was actually quite a controversial claim to be making in his day. It's a violation of the basic monotheistic ideas of Christianity, as well as Spinoza was a Jew, actually. So his Judaism was also kind of in contradiction to what he's talking about here.
So he actually got in a lot of trouble, had to go into hiding, because what he's really talking about is pantheism. that everything is God to an extent, right? But in this case, it can solve the mind-body interaction by suggesting that there's no interaction that has to be solved at all, right?
That merely what's happening is that what's happening in the mind and what's happening in the body reflect the same underlying causal force. So in this case, going back to our example, if I want to scratch my head because I... have the idea, I want to scratch my face, and then my hand comes up here and scratches my face, that's not cause and effect. My mind did not cause my hand to do that.
Instead, what's going on is that, according to Spinoza, God wanted that to happen. And it happened in both the mind and the body at the same time, without any back and forth cause and effect going on there. We might then also see that... This would imply some things about human free will, which is that it cannot exist. So we see another difference with Descartes rejecting free will here by Spinoza with determinism.
He says that it would be wrong to exempt the mind from the so-called unity of nature, right? The idea is that all of nature is united as God is the ultimate cause of everything. But if somehow the mind is able to be exempt from all of that stuff and to...
not be a part of all of that stuff would just be an unnatural kind of philosophy. So he says that it has to be the case that mind, body, and nature must all be part of the same thing. He says that, so cause and effect, right?
Everything has a prior cause. That's just an absolute truth. He says that we only think we have free will because, you know, it's like saying it's an illusion.
Really what it means is that we oftentimes merely, we just don't think about. the causes of our own actions, right? Why are we doing what we're doing?
Well, if you stop and think about it, there's probably a reason. There's some prior cause. We just usually don't do that.
We usually don't sit down and think about that, right? I could be asking, why am I sitting here right now trying to explain the concept of free will to you? Well, of course, I'm doing that now because I need to get this lecture recorded for the semester that starts tomorrow. But then I would also ask the question. Why do I have to prepare a lecture for this semester?
Well, because UCF hired me to teach this class to you. Why did UCF hire me to teach this class? Because I applied. Why did I apply for this job? Because I got a PhD in psychology.
I need to have a job doing it. Why did I get a PhD in psychology? Well, because I got a bachelor's degree in psychology. Why did I get a bachelor's degree in psychology? Well, that was 30 years ago, so I couldn't quite tell you the whole story.
I don't remember, but there must have been some reason that I was interested in all that sort of stuff. The basic idea is that there is a long chain of events here, a long chain of cause and effect that have led me to being at this point in my life, sitting in my house at midnight the night before the semester starts, recording this lecture on Spinoza. So there is, in fact, that chain of events, right? But we don't normally think about those things, right?
We can't. And if we do, we will realize that, oh, yeah, there's a lot of prior causes that have led me to be doing what I'm doing right now. But since we don't think about them, we tend to ignore it.
Therefore, it becomes an illusion that we are just spontaneously doing things. That, oh, I'm just going to spontaneously do whatever, right? No, right?
If you really think about it, every choice you've made had a prior cause. That's at least what Spadoza is arguing. In a similar way, Leibniz is going to give us a dualistic theory, but abandoning the dual substance.
part. So he has another single substance theory, but he's got a different substance. Instead of God, we get monads.
Monads should be thought of as a little bit like atoms, but rather than the more inert, lifeless atoms of Democritus, we're talking about living atoms, a form of living energy. And something else that is somewhat similar to Spinoza is Leibniz is saying that all of these atoms, all of reality has consciousness. That consciousness is itself a pervasive permeating aspect of the universe. Everything has consciousness.
So that term is actually called panpsychism. I didn't put it in the notes here, but panpsychism is the idea that consciousness is part of the universe. Leibniz gives us a hierarchy so that we can have different kinds of monads that have different kinds of consciousness.
So again we have God as the supreme monad. So supreme monad here capable of knowing all. We use the term like omniscient. for that, right?
To know all. So that's the supreme monad. Human minds are not capable of all-knowing omniscience, but we are capable of logical, rational thinking. So that means the human mind is made of rational monads.
Step down the hierarchy, right? Animal minds are not capable of logical thinking. Leibniz here would agree with Descartes in that regard. And so... We would say that animal minds are made of sentient monads because they are self-aware, right?
Animals are aware that they exist, that they have feelings, perhaps, that they have needs, that an animal knows when it's hungry, for example, knows what it's like to be hungry, knows what it's like to exist. So that's awareness, that's sentience. So they have sentient monads.
And then there's all the other matter in the world made of simple monads, rocks, ink pens. even your body, right? Made of simple monads, not conscious, but conscious.
What does that mean? Not self-aware, but conscious. So maybe the better term is maybe say unconscious, right? So a rock, for example, doesn't feel hungry, doesn't know what it's like to exist, doesn't know what it's like to be a rock. There is nothing to be said about what it's like to be a rock.
But nevertheless, the rock made of simple monads must have some kind of consciousness. Even if it doesn't rise to the level of awareness, it's still a form of consciousness or unconsciousness. And so with consciousness being a property of all monads, now there's no more of a problem to be explained, to understand how mind and body could somehow coexist.
Everything has consciousness, all monads, everything is made of monads. Monads can interact with each other in a way maybe a little bit like the atoms are but we do have Another kind of parallel with with Spinoza here with Leibniz Which is that the mind and body do not really interact with each other, right? So again, we're trying to avoid the mind-body interaction of Descartes because it seems to fail So the mind-body get to be separate from each other we get the dualism because they're made of different monads but they're not going to interact with each other.
So just like Spinoza said, if I have the idea that I want to scratch my face and my hand comes up here and does this, that what's happening is that those two events are perfectly synchronized to occur. They've been predetermined. So here, what Leibniz would suggest is that God created the universe at the beginning of time and that everything happening in the minds of all humans and all animals and everything happening with bodies and physical objects in the world are all following a predetermined timeline.
It's like a wind-up toy that God created at the beginning of the universe. Everything is unfolding according to this predetermined timeline. And so it's all in perfect harmony. They're working in parallel, side by side, all events unfolding in all of these different domains all at the same time.
And so it just happens that at some predetermined time, I'm going to have the idea, scratch your face, and then my hand's going to come up here and do it. And it just perfectly coincides with each other. even though my mind did not actually tell my hand to do that, right?
It's all predetermined. So something we see in common between Spinoza and Leibniz is that in their attempts to eliminate the mind-body interaction, but keep this single substance dualism kind of stuff here, that along the way we've lost our free will. So that's a kind of a weird thing here, is that Descartes'theory doesn't work very well, because we can't find a way to make mind and body interact with each other. But if we eliminate the interaction, we have to eliminate free will. Seems, at least seems to be the case if you're Spinoza and Leibniz.
This pretty much wraps up our chapter four, though we also, I want to thank get you thinking about chapter five because there are other options right we could move away from this dualism entirely and get more towards something like materialistic monism or idealistic monism um but it's really going to we're going to have to to change our geographic setting a little bit and jump across from continental europe where all these guys are to to the british isles and look at the english and irish and scottish philosophers who are going to to you really take things in a different direction. They're going to move towards empiricism, they're going to move towards monism of various types. But these dualistic and rationalist ideas are very old. They've been around for a long time, so they don't go away overnight. And so it takes a little bit of a cultural difference in the British philosophers to really be willing to make that leap.
So stay tuned for chapter five.