Transcript Reading: Finishing Leibniz Pivoting to British Empiricists

I'm going to proceed with our philosophies, taking them in order. And I said that today we get to the British empiricists, and I intend to do that. But I think there are a few things I ought to say about Leibniz and his view because it is so strange. You wonder to yourself, what's going on here? How can somebody convince himself that reality is really the way Leibniz’s theory describes? What leads these people to ignore their everyday experience so easily, kiss it off as "that's just how things appear, it's not how they really are," and then go to some elaborate scheme, like Leibniz’s idea of monads that are windowless but pre-programmed to know what else is going on and so on? It sounds wild, and I think it is. So, what encouraged people to do things like this? And what are they assuming?

We covered one of those things when we looked at the slogan, the real is rational and the rational is real. But there has been in European culture, prior to these guys, a stark and really important discovery about astronomy that fires all of this attitude. What I'm talking about here is what we call the difference between appearance and reality. This is what we experience, but for reasons, we set that aside, and reality is really quite different from what we experience. What on earth would have encouraged people to think like that?

The answer is Copernicus’s view of the solar system. Astronomy is a science already in this century, mathematics is considered a science, and its application to what we see in the heavens, especially at night and especially for the purpose of navigating ships across the ocean in trade. Copernicus comes up with the theory that the planets revolve around the sun, not the sun and moon around the Earth. The moon travels around the Earth, but the Earth goes around the sun, not vice versa. And he works out all the math, and the math predicts more accurately than their old theory did, the theory of Ptolemy that the sun revolves around the Earth. The math in Ptolemy's system was always a tiny bit off. You know, you do the math, and this is when the sun should rise, and this is the spot on the horizon where the sun should rise, and it comes close, but it's not exact. But when you do the math from Copernicus’s theory, the sun comes out bingo where it's supposed to and right on time.

In other words, rational investigation and mathematical calculation overrule what we experience. What we experience makes it look as though the sun rises and sets, but on Copernicus’s new theory, that's not what's happening. What's happening is that the Earth is turning while orbiting the sun. I want to read you what Galileo said about that. He said, "I cannot express strongly enough my unbounded admiration for the greatness of these men." And he's referring to Aristarchus, who held this view of the solar system in the ancient world, and Copernicus, who rediscovered it and championed it in Galileo's own lifetime. "They conceived of the heliocentric system—that the sun is at the center of the solar system, the planets go around the sun—and they held it to be true in violent opposition to the evidence of their own senses."

So instead of perception of things, events, and states of affairs that have all kinds of properties being the beginning of our investigation, under the influence of the Copernican revolution in astronomy, everyone is willing to start with rationality and allow that to override and defeat the evidence of our senses. If our senses show us one thing, and rational—that is, logical or mathematical calculation—shows us something else, we're going to believe the something else and not what our senses show us, because we know they lie. They show us the sun rises and sets, but it doesn’t.

Now, that's what lies behind a lot of this, and it's what encouraged a slogan such as, the real is rational, and the rational is real. It's going to override anything that you perceive because we know perception can be deceived. There can be hallucinations. There can be anomalies of perception so that we see what's not there, or see a process and think that that's real, but it's really something else. And that's the lesson from Copernicus. Galileo thinks that's a marvelous example of doing science and being rational, to accept something in violent opposition to the evidence of their own senses. So that's what encourages this difference between appearance and reality.

First of all, appearance has been degraded. It has been equated with sensations, sensations as they occur inside our minds. And we certainly want to say that reality is more than just sensations. The sensations in our minds, to be worth something, have to be faithful copies (these people believe) of what is outside us, of the external world. But since the sensations that our minds have are only phenomena or sensory properties, they have only properties such as being colored, making a certain sound, having a certain feel to the touch, taste, and smell. They identify sense perception with sensory properties, but that’s a faithful equivocation. That means shifting the meaning of the term. The fact that something is known through sense perception doesn’t mean it has only sensory properties. That's an assumption they all make and never question.

So that's why you get somebody like Leibniz with a system that makes both mind and matter, as we experience them, not to be real. What's real are monads, and since that yields a rational explanation of everything, and it all turns out not to be self-contradictory, it must be real.

So in Leibniz's own view, physics, for example, does not consist of investigating the physical world that we perceive. It consists in elaborating the concept of a monad and then drawing from that all the things that follow about it and saying that that's the way the world really is. It may violate the way it appears to us in sensation, but so what?

So he has the system. He begins with God as the necessary being. And God is, I guess, an infinitely great monad or something. But it means God has a physical side because God has physical forces. True of God is not that He created all physical forces, but that it is part of something He has. And because there's no contradiction in this idea of God, nothing could hinder it from being real. Therefore, it is real. It's not just possible, it's actual.

This means that what we call bodies in motion in space are not real. Only monads are real. Low-level monads have only very limited consciousness, but high-level monads have very fine-tuned abilities to perceive and think. Looked at from outside, monads would look like what we perceive, but they are, in fact, bodily units of force that can relate to one another in ways that are already stated and calculated mathematically. So they are the reality that should be taken to override what we sense and perceive. And if you think that ends up dismissing how the world appears to us and taking as reality what theory leads us to believe, you're right. That's just what it does. Provided the theory doesn't contain any contradiction, it's right.

And if your response to that is, "Surely philosophy can't take that view, I mean, that can't be a permanent contribution that continues to this day," you're right about that too. Allowing our flights of fancy to go and then declaring them all real, provided there's no logical contradiction in the definition of what we're talking about, is not persuasive and nobody follows it. There are no Leibnizians today, for example, who are willing to commit to the monad theory. No.

But the comments of Galileo still hold. When we get a theory that says, "Here's what's really going on," and we test it, and we get the result it would predict, and it all works out mathematically, we tend to believe it. And the more evidence that is compiled that works out to be what we would expect if this theory were true, the more we feel confirmed in that belief. It's not an absolute proof. It can't be. I'll show you why.

Suppose we want to come up with a theory about why paint undergoes color changes with different colors. When you mix different colored paints, you get changes. So suppose I have,

Premise one: I have blue paint. Premise two: I have red paint. Premise three: I mix them.

Now, what I know happens is—I'll put it way down here—paint turns purple, okay? But I don't know why. Why does the paint turn purple, not brown, black, or green? If I stick my head in the paint and watch it get mixed, I still won't know. I won’t see anything that’ll give me any answer to that.

But suppose then I create a theory. A theory means an educated guess, or a series of them. So I'm going to make educated guesses as to what's going on. 

I'm going to say paint is made up of particles, and I'm going to call them molecules. You can see I'm being highly original. Okay, the paint is made up of tiny particles called molecules. And molecules stick together. They bond and form different shape clusters because of the shape differences, the clusters reflect different wavelengths of light.

So if these molecules bond together and they form one shape or another shape, then what I'm saying is one cluster shape reflects blue light or reflects wavelengths that we perceive as blue. Another paint has a different shape cluster, and it reflects the wavelengths that we perceive as red. And when we mix them together, they form a new cluster shape that reflects the wavelength we perceive as purple. And so the paint turns purple.

This is a theory, a series of hypotheses intended to explain why these given facts result in this given fact: we see this, we see this, we see this, but we don't see these—these additional premises about the wavelengths being perceived as different colors, and so on. That's how a theory works. And a lot of people are under the impression that when we propose a theory, then we can do an experiment that will prove whether the theory is true or false. That's not quite right, and the way in which it's not right is important to know. So I'm going ahead with that just a bit, too.

It's not that we can perform an experiment such as mixing the red and blue paints and see that they turn purple. How will that tell us whether this stuff is true in here? Well, it won't. We can make up another theory. I can make up a theory that goes, paint is inhabited by invisible paint Pixies, and the blue paint Pixies and the red paint Pixies don't like each other, and when you mix them together, they spit purple on each other, and you'll still get the conclusion that the paint turns purple. That's not a very good theory. And why not? Well, it's not because we can't see such things as paint Pixies, because normally we can't see such things as molecules either. Now we can see them under an electron microscope, but it takes elaborate and significant equipment and power and so on in order to get an image of a molecule. So why is one of those a good theory and the other not?

One of the reasons is because the constituents of this theory—the molecule—can now be transposed into other contexts and give us explanations of other things that they weren't invented for. If they were invented to explain paint color change, it turns out that they now explain heat exchange too, or they explain a great many other things. So they're transferable. That's one reason. Their outcomes can be calculated and written mathematically. That's another. You can't put a mathematical formula to predict what Pixies are liable to do, and what they're not—you’re just making all that up anyway.

You get the idea. It becomes a theory that explains yet other things that it wasn't originally invented for. And then, the more we see those predicted results that confirm this, the more our confidence is that the theory is right. But we never absolutely prove it, and I'll show you why. This is just a wee bit of logic. There's a logical rule that goes like this: If P is true, then Q is true. P is true, therefore Q is true. So if this says, "If it rains, the sidewalk will be wet," it rained, and the sidewalk got wet—that's a legitimate rule.

Here's one that is not a legitimate rule: If P is true, Q is true. Q is true, therefore P is true. Nope, not right. This is a rule. It even has a name: It's called modus ponens (I'll just put MP), and this is a fallacy.

Look at it again. "If it rains, the sidewalk will get wet. The sidewalk got wet, therefore it rained." Not right. Here's a legitimate logical rule: If it rains, the sidewalk will get wet. It rained, and it got wet. This one says, "If it rains, the sidewalk will be wet. It got wet, therefore it must have rained." Sorry, melting snow, a garden hose—there are lots of things that could have made the sidewalk wet, and that doesn't show that it was rain.

So this form of an argument that goes, "If P, then Q. Q, so P," is not a logically valid inference. Now take a look at what is being suggested by the guy who says, "We construct a theory. We do experiments, and if they come out the way the theory predicts, it shows the theory is true." Which of these logical forms does that argument take? Well, it takes the form of: If the theory is true, then we get X. We do the experiment, and we do get X. Therefore, the theory is true. Which of these two forms does it follow? Is it modus ponens or the fallacy? Clearly, it's the fallacy.

If this, then that—we get that, so this must be true. No, it doesn't follow. What follows instead is that we look at the theory and see what it predicts, what inferences we can draw about what it would predict if this theory were true. We do experiments, and if we get what the theory predicts, it doesn't prove beyond all doubt that the theory is true, but it increases our confidence. It tends to confirm the theory, that's the way we put it. But there's no once-and-for-all absolute proof that a guess like that is true if the guess consists of postulating that there are certain kinds of realities. Suppose it says nobody's ever thought of this idea of a molecule. I'm postulating that there are molecules.

Okay, you know what proves it's true? Building an electron microscope and seeing them. So there may be a number of theories that plug molecules in as the explanation and give us results we can test, and we test and test, and all the tests turn out favorably. It increases our confidence; it confirms our belief. But molecules cease to be a theory when we build an electron microscope and see them. Now it's not a guess anymore, alright?

Having made that clear, I hope, we are now going to proceed to the philosophers who flourished on the continent in these same two centuries. And they are John Locke—let's start that over—Locke, Berkeley (Berkeley, he wanted his name pronounced this way, so I'll try to do that), and David Hume, the last of them, being everybody's nemesis.

Hume comes in and wants to employ strict logic, taking everybody's theories and leveling them—nothing works. And having destroyed the field around him, he washes his hands of it and walks away. But in doing that, if he was right, he would have also destroyed two things that the last thinker, Immanuel Kant, is especially fond of and thinks we can't live without.

And those two things are science and ethics. "You can destroy other people's theories if you want," says Kant, "but you don't get away with getting rid of physics, and I can't let you get away with leveling ethics, because mankind needs ethics in order to survive and uses science in order to gain control of the world around him and better people's lives, and I will not let you get away with that."

So Kant is the big hero. He rides in on a great white horse, wearing a white hat, and he's going to save Western thought—Western philosophical and scientific thought—from the onslaught of David Hume. He's going to rescue it and show you how science is right, how physics gives you certainty, and how there is certainty in ethics too, even after Hume has, to his satisfaction, leveled the field so that nothing is left. We'll see why.

Now, what I think would be useful before plowing right into Locke, the first of these theorists, John Locke, is to give you some background about what was going on in England at the time. I did something like this before tackling the continental rationalists—I talked about the 16th century and the three cultural forces that arose in that century in competition with one another. And what we would see as we continue our study of these different thinkers is that the rationalism revived by the Renaissance came out the victor. Sure, there were still people who were advocates of the Reformation, and there were still people who stuck with the old medieval arrangement of King and Church, mostly Roman Catholic, while the Reformation people were called Protestants—people who protested against the Catholic establishment. But what takes over in the driver's seat as far as European culture is concerned is the rationalism revived at the Renaissance.

The Renaissance first revives rationalism in things such as architecture and dress and creating new devices that make life easier and so on. But it very rapidly morphs into "the real is rational and the rational is real," and thinkers propose great, elaborate schemes of what the world is really like, despite what appears to us through our sense perception.

But now we're going to shift to people who, while they’re going to make use of reason and agree that the rational method is good—they want to make their arguments logical, and they want to make the calculations by which they adjudicate theories mathematically sound—those are tests for truth. But they do not believe that if anything just doesn't contradict itself, it must be real. No, if you want to know what's real, go to experience; that'll show you what's real. And if we then need a hypothesis about something that we can't see, it's going to be justified by how that hypothesis fits with what we do experience. They're not so willing to dismiss sense experience. That's where we're going to start.

That sounds even better than they carried it out, because, as I already said, what they did then was a faithful and—I think—grossly mistaken identification of what we experience with what they call perception or sensation. Hume calls them sense impressions. But note, sense impressions, as they defined them, had only sensory properties—I've said this before—properties of color, sound, taste, touch, smell, but they did not have properties that were spatial, quantitative, logical, or physical. So if you start with that, the question is, how do you get from sensations—viewed as only sensory things—to the rest of the world as we experience it? To the physical, the spatial, the logical, the linguistic, the social—how do you get the rest of it?

The upshot of their investigation was that you can't. If you lock yourself into perceptions being only sensory, little fragments of objects having only sensory properties, you'll never get the rest of the world back. And that's what Hume turned on everybody. He assumed also that there were only sense perceptions. And he went from that to show that you could never get anything else, and all the other things were just "Abigail dominiak"—making up stuff with no grounds. None of it can be justified rationally, and so it should all be dumped. That's where Hume left it.

So let me say a little bit about the background—historical background—of what's going on in England now, as opposed to the continent. Given that these people are all empiricists—I'll put that up again—that is, they want to start with experience, and they want to have knowledge of the world from experience, even though they have a wrong idea of what that is, they still want to keep what they think is much closer to common sense.That is, instead of saying, it looks to us as though there are physical objects and they move around in space, but really, there are only monads that are force points that we never perceive. These guys are saying, "Whoa, get out of here with that. You're just letting your fantasies run wild." So they aim to keep the common sense view. There may be a difference between appearance and reality, but there can't be that big a difference. What they want to do is keep the appearances, if they can, and it's called save as much of the appearances as possible.

Save as much of the appearances as possible. So they want to begin with experience, and they want to save as much of it as they can. They all want to begin with an analysis of how the mind works.

How the mind works. We have our given experience. We know we can't just spin stories into the sky like, "There are monads, and everything is really the same thing in God," and wild stuff like that. So let's start with the appearances and then analyze what it is the mind does when it perceives. What is it doing when it reasons? How does it operate? What are the powers and limitations of the mind?

And they need to define the powers in the human mind: what can it do, and what are its limitations? They’re going to do this by introspection. They're going to examine and analyze their own minds, catch it in the process of theorizing, and ask, "What is it doing?" Now, you see, you get the idea. Sure, you do. The first guy who started this was John Locke, and Locke had, by training, been an MD. He was a doctor, and he proceeds in philosophy the way a doctor would proceed in an examining room. You want to know what's wrong with the patient? You don't sit down and make a theory—you examine the patient, and then you try to understand what's wrong. After that, you prescribe the proper medicine.

And Locke exactly follows that procedure in his philosophy. You want to know about objects around us? You want to know about things that are physical? We're going to examine them. We're going to find what laws they conform to, and so on, and we're going to explain them in such a way that it retains as much of what we perceive as possible. Yes, Copernicus went against the way the sun appears to rise and set, but the explanation of what's really happening also explains why it appears to us that the sun rises and sets. See, the Copernican theory doesn't just say, "Okay, the sun isn't really rising and setting; the Earth is turning," but it explains why it looks that way. From the standpoint of someone on Earth looking at the sun, you'll see it rise and set. And, of course, according to relativity theory, both are true descriptions. You can easily say that the sun rises and sets—that's from the perspective of somebody on Earth. And you can say that the Earth turns—that's from the perspective of somebody who's backed off into space and is viewing the sun and the Earth. It's the Earth turning. Neither is wrong in relativity theory.

Okay, you get where Locke's coming from. He worked as a doctor, and it took him 20 years to write his Essay Concerning Human Understanding. What he offers is an analysis of the mind—how it works, what science can and can't do, and so on. And there are places at the end of the work where he contradicts something he said at the beginning. Well, it had been 20 years since he wrote the beginning! The work isn't self-consistent all the time, but there are a lot of good points in it.

He tries to draw practical results from his philosophical theory, his theory of reality, and his theory of knowledge. He tries to draw practical results for a political theory. Now, Descartes mentions that from his theory of reality and knowledge, there are certain things that follow for ethics, but he just mentions a few of them. He doesn't show how they follow or what kind of overall ethic you would have, or how you would answer different problems. He didn't live long enough to get to that. Spinoza didn't elaborate much in his theory of reality or knowledge; he was only concerned to show how it supported ethics. So he only went so far as what he thought had ethical consequences, and then he tries to treat ethics like it's mathematics. He even calls his work Ethics: ethics done like geometry. He’s going to give you his definitions, his corollaries, and he's going to draw inferences and give you proofs—this is wrong, that is obligatory, this is good or evil, and so on. He's going to work it all out in great detail.

Leibniz works more on the theory of reality, draws conclusions for his theory of knowledge, but doesn't get around to an ethics or a political theory. So here's Locke, taking this different tack—the empiricist tack—rather than the rationalist tack. It’s not that you ignore what you sensorially perceive, and reason gives you the fabric of reality, and if you can deduce it without contradiction, you must be right. No, you want to know about reality? You go to sense perception first—what you perceive.

Now, I think that's right, but I think sense perception is more than what Locke allowed it to be. I've already said this, and I know I'm repeating myself, but I want you to get this clear. Sense perception is where we start; it may not be where we end. And sense perception, from the beginning, is thought to be not of things, events, states of affairs, laws, persons, relations, and so on—all the stuff that we actually do experience—all the things that are the proper answer to the question, "What is it that's given in experience?" Instead, they substitute an abstraction from those things. They substitute supposed sense data or sensations or percepts or impressions—whatever term they want to use. They're thingies that have only sensory properties or phenomenal properties—whatever term you want to use: only colors, tastes, sounds, touches, smells. That's all that sense data have true of them—sense impressions, that's Hume's term.

So they're going to start with that, and that’s what Locke starts with. And every one of them—Locke, Berkeley, and Hume—wants to start with experience and misconstrue it in this fundamental way to begin with. And when Kant comes along and wants to rescue the world from the intellectual devastation Hume produced, he also starts with sense perception as impressions that have only sensory properties. However, Kant recognizes that they have more—that they also have logical, mathematical properties as well—and he's got a theory as to how they get them, how our sensations get to be that way.

And Kant also is going to start with a critical analysis of how the mind works. What are the powers and limitations of the mind? Now, Locke thinks he's done that. Berkeley, not so much—he doesn't dwell on the powers and limitations. He goes right to the sensations and wants to say, "That's all we ever experience, so that's all we know." But Hume goes back—he wants a critique of how the mind works and what are its powers. Kant says, "That's absolutely right. That's the first thing we're going to do. Only I'm going to do it right. These guys didn't get it right. We're going to start by wiping the board clean of all assumptions." But he doesn't really, because he still assumes that experience means little thingies that have only sensory properties.

Okay, sense perception is reduced from being objects like tables, chairs, clouds, mountains, people to being bundles of sights, tastes, sounds, touches, and smells, and therefore it leaves out all the other properties. He's going to explain why we experience things that are only sensory as having all these other properties. Fair enough. But they all make the same initial mistake about what it is we experience—what’s just given to our experience—and they all want to start with that, and they all make the same mistake about it.

Now, the background to how this gets rolling here is interesting because these three British empiricists—Locke, Berkeley, and Hume—are not professional philosophers. They all made their living in another way. The three continental rationalists made their living as philosophers. Descartes was independently wealthy as a young man, fell on harder times (and I told you that story), took a job tutoring the Queen of Sweden, and between the rough climate and having to get up at 5 a.m. to meet her class (well, you’d get up at 4, wouldn’t you, to meet her class at 5?), he got pneumonia and died.

But Spinoza made his living partly through his writing, but mainly by grinding lenses for eyeglasses. Leibniz, on the other hand, made his living as an intellectual, as a scholar. He was an advisor to a king, devised the defenses of a city, wrote about mathematics, wrote about theology, and tried to bring about a reconciliation between the Roman Catholic and Protestant churches. He wrote a lot and invented calculus. So, he was making his living by his wits. No doubt.

Over on the continent in Britain, Locke was an MD, the private doctor to Lord Shaftesbury, a nobleman. He saw the investigation of philosophy into reality and knowledge as much a part of what a doctor does. Fair enough, I think it's a healthy corrective to those continental rationalists. Berkeley was a bishop, and that's how he made his living. He wrote in his spare time and produced major works that made a huge impression while he was still a young man. Philosophers tend to be old guys—it's after they've lived with the current theories, drawn out the consequences, seen what holes need to be plugged, and figured out what failings the theories have. Then something occurs to them—a new way to approach the problem. But Berkeley was still a young man when he did this, making him the exception to the rule. In fact, Plato even comments on this, as did Hegel later on. Philosophers themselves reflect on the fact that you have to live with something for a long time to see what's really wrong and to get clear ideas of another way to approach the problem. So, Berkeley is an exception in this case.

Hume was a mature man, though I won’t say he was old, by the time he came around. He was very influenced by Berkeley, though he never acknowledges it in anything he’s written—nothing I’ve ever seen. He never says, "As Berkeley said," in his formal writings, and people have wondered about this. I mean, Hume begins where Berkeley left off. He assumes Berkeley was right and is going to draw the consequences that Berkeley refused to draw. It’s puzzling—did Hume come up with this on his own? Could it be he never read Berkeley? And then, a few years ago, sometime in the 1980s, some letters of Hume were uncovered in which he mentions having read Berkeley. So, our suspicions were confirmed. Hume wasn’t trying to deny it; he just didn’t think it was worth telling you about. So, he starts where Berkeley left off, and he carries it out to the logical extreme. It levels everything. You don't have a science of physics. You can do math, but all you're doing is following formulas. If you follow the rules, the results turn out right—it’s like a game. You make the rules, and if you follow them, it works out. But it tells you exactly nothing about the real world you live in.

That’s Hume. Then Kant rides in to save science and ethics. He can't save belief in God. He can't save belief in external, physical objects. There's a lot of stuff he can't get back, but he's going to get back physics and ethics, and we’ll see how he tries that and whether he succeeds. In my opinion, he fails miserably, but that's just my opinion. You're not bound by my opinions, and you're free to form your own and write them up as they’re appropriate in the writing required of you. Do the reading, and next time, I'll start with the historical background to Locke—what life was like then in England, what was going on, and how Locke zigged and zagged and maneuvered to keep his freedom and his ability to write, and how that turned out to inspire the whole tradition that includes Berkeley, Hume, and Kant.

With Kant, we return to the continent. Kant is German, living in what was then East Prussia, the extreme northeast corner of what counted as Germany back then. And we'll then end the course proper with Kant, but we will go on to do a survey of the 19th century, and then another survey of the 20th century. So, get your mindset ready to do all the reading.