[MUSIC] Parmenides' Prohibition. Parmenides presents a profound objection to pre-Socratic naturalism. It's an objection to which every subsequent thinker in the naturalist tradition must respond. What Parmenides objects to in the naturalist tradition, is one of the things that Heraclitus emphasized and celebrated. That the natural world is a world of change. A naturalist's bumper sticker would read, Change Happens. Parmenides disagreed. He argued that the very notion of change is incoherent. All of those who believe in change, he argues, are traveling along a path of inquiry that is absolutely forbidden by reason. So, let's start by looking at that forbidden path, which is one of two routes of inquiry that he distinguishes. Now, this is all going to be very abstract, but we'll relate it to some concrete examples. Let's start with fragment B2, where Parmenides marks out what he calls, the only routes of inquiry that are for thinking. Or I might translate it, the only routes of inquiry for thought to take. The two routes are quite simply is and is not. Now, his exposition of the two routes is a little complicated here since he also describes two policies that an inquirer might follow. The first policy, is to take the is route and reject the is not route as impossible. That's the right policy according to Parmenides and the one he exhorts us to take. The alternative policy is that the is not route is perfectly okay. This is the stance he wants to disabuse us of, don't go there, is his message. So, let's focus on the two routes. Is and is not. And try to appreciate what they are and why we are not supposed to go down that second one. We can think of the is route as as the category of affirmations. For example, when I think that France is in Europe or I say that whales are mammals. I am making an is claim, maybe in the plural. When I go down the second route, the is not route, I am making a denial as when I say, there is no Loch Ness Monster. Or when I think that Europe is not an island. In saying that these are the only roots of inquiry, is and is not, Parmenides is proposing that anything you might think or say is either an is claim or an is not claim. Can you think of any exceptions? If you can, could you translate them into an is or an is not claim? Now, Parmenides's big point here, is that we have to stop using the is not claims. He says, hold back your thought from this route of inquiry. And do not let habit, rich in experience, compel you along this route to direct an aimless eye and an echoing ear and tongue. But judge by reasoning, logos, the much contested examination spoken by me. In other words, we are in the habit, he says, of using both is claims and is not claims in our ordinary thinking about the world. And also in our scientific investigation of it. But this is just a bad habit of unreflective thought. Properly rational and scientific practice, he says, has to be restricted solely to is claims. But what's wrong with is not claims? Parmenides’ objection in a nutshell is the following. When you say or think that something is not, there has to be something of which you are saying or thinking that it is not. But then, that something is, while you are saying that it is not. So, it turns out that you are saying it is not of something that is. Now let's consider an example. Suppose, Step one, I think there is no Loch Ness Monster. That's an is not thought. Step two, so, I am thinking about the Loch Ness Monster. That's the subject of my is not thought. Step three, so, there is a Loch Ness Monster. The argument starts from the premise that I am thinking an is not thought. That's step one and draws the conclusion that this thought is false. That's step three. The conclusion is pretty embarrassing for anyone who accepts the first premise. If I am thinking that there is no Loch Ness Monster, then there has to be a Loch Ness Monster? And the argument can be generalized to any claim of the form, there is no, fill in the blank. What's the point of thinking any, is not, thoughts if they are all going to be false? As Parmenides tends to put it, anyone who tries to think an is not thought, is trying to think that what is not is. So, that's the sort of muddle you get into if you try to say or think anything of the form is not. Or so Parmenides tries to convince us. Are you convinced? Do you really think that it follows from the fact that you are thinking there is no Loch Ness Monster, that there is a Loch Ness Monster? Let's examine the argument in more detail. We should note first of all, that the argument has a single premise. Step one, and it makes two inferences. So, we have to see whether we accept the premise, and whether we think the inferences are valid. Let's start with the premise. I think there is no Loch Ness Monster. Well, I certainly agree with that, that's what I think. So, I have nothing to object to here. So now, what about the inference to number two? If I am thinking there is no Loch Ness Monster, then what am I thinking about? What is the subject of my thought? This seems pretty straightforward. I'm not thinking about Santa Claus or the Abominable Snow Monster, but the Loch Ness Monster. So, it looks like the second claim follows from the first. Now, let's consider the inference from the second claim to the third. Does it really follow from the fact that I am thinking about the Loch Ness Monster, that there has to be a Loch Ness Monster? Parmenides seems to be assuming that anything we think or talk about has to exist. That's why he says at the end of fragment B2, you cannot know what is not, nor can you declare it. We can make this principle an explicit step in the argument and add it after step two. Parmenides’ Principle, if I think or speak of x, x must be or x is. Now, if we accept both two and Parmenides Principle, I think we have to accept that three follows. But should we accept Parmenides Principle? Why believe that anything you can think or speak of has to exist? Well, you might ask, how is it that our thoughts or words manage to be about things at all? Now, that's a real philosopher's question. It's something we take for granted as thinkers and users of language. That strings of sounds that we utter and stuff that goes on in our brains, manages to mean things. And in particular, to be about things in the world. How is it when I say dogs, I'm talking about dogs? Now, it won't do to say it's simply a matter of convention, since in French I wouldn't say dogs, but les chiens. Yes, it's a matter of convention whether we use dog or chien to do the job, but how do we get the job done? How is it that either word manages to pick out, point to, or refer to dogs. Now, it's not at all ridiculous to suppose that the answer to this question will be a story involving dogs. And so, an elementary theory of meaning or reference might include, or at any rate pre-suppose, something very like Parmenides' Principle. And this is a principle that makes it deeply problematic or paradoxical how we could manage to think or talk about what isn't there. And that's pretty much Parmenides' message. Thinking or speaking about what is not is impossible, since there is nothing for our thought or speech to be about. We may utter the words and believe that we are thinking meaningful thoughts, but in reality, he tells us we are just babbling. But if we want to insist against Parmenides that we are not babbling, what are our options? We can't just walk away from the argument and say sorry, I don't believe the conclusion. Because that's just being dogmatic. Parmenides has given us an argument for that conclusion. And so if we don't accept the conclusion, we have to find something wrong with the argument. Now, one option is to reject Parmenides's Principle and the theory of meaning that motivates it. But on what basis? Because it delivers a conclusion we don't like? That seems question begging. Rejecting the theory would be more respectable if we have an alternative theory of meaning that could both explain aboutness. And also make sense of is not claims. But coming up with the theory of meaning is a lot of work. Alternatively, we might revisit the question of whether the second step in Parmenides' argument follows from the first. It seemed pretty innocuous at first to suppose that my thought, there is no Loch Ness Monster, in step one, is about the Loch Ness Monster. But once we have the theory of aboutness like the one Parmenides is presupposing. It might seem more prudent to suppose that my thought is about something more complicated. For example, that it's about the Loch Ness, about serpents and frightening experiences in boats at night. All of them things that exist, but that don't all add up to the existence of the Loch Ness Monster. Now, something like the latter is the tack that most of Parmenides' successors take. When they try to rehabilitate is not claims from his accusations of incoherence. But that's the story for another lecture, where we will also get to the tie in with change.