The rules that we've looked at so far apply to every use of language. But we want to focus on those rules that are important specifically to arguments. At least normally, misspelling or mispronouncing a word doesn't affect an argument. Of course, if you pronounce one word so that it sounds like another word, it can be very confusing and people won't understand you. Or if you misspell it so badly they don't know what word you wanted, the argument is not going to work. But normally misspelling and mispronunciation don't make the argument bad. Instead, what affects the argument is what's going to affect the proposition that's getting expressed. The meaning of the sentence, because that's going to affect whether the premises justify the conclusion or whether they explain the conclusion. and so, we need to focus on those rules of language that in particular deal with the meanings of words and of sentences. So what's meaning? Well, one thing I can tell you is we're not going to be talking about the meaning of life in this course. The meaning of life is a totally different topic. We're also not going to be talking about whether clouds mean rain in the sense of giving some indication or evidence that there's going to be rain. We're concerned with the meanings of words and sentences in language. We're concerned with linguistic meaning in particular. So, how are we going to understand linguistic meaning? Well one way to think about the meanings of words and sentences is to ask how you would explain them to someone who doesn't understand them, like a small child or someone who doesn't speak this language. Well if somebody said, what's the meaning of the word chair? You might go, well when I use the word chair, I'm referring to these things you know, something like this. when I say, I am sitting on the chair, what I mean is my body is above the chair. And so, that approach to teaching language suggests to many people that what words mean is the same as what they refer to. and what sentences mean are the facts that they try to describe. Now that view of language is often called the referential or descriptive view of language. So is this referential or descriptive theory adequate? No, no, no, no! Absolutely not! That theory does not cover a lot of language that's extremely important. Just think about greeting someone in the morning. Hello! Are you referring to an object when you say, hello? Or think about the word not in a, in a sentence, and that the word not is going to be crucial to arguments, but does the word not refer to something separate from the other things? Well, if it did, then there would be more objects in the room when I'm not sitting on the chair than when I am sitting on the chair. So you cannot understand the meanings of many words, like hello or not or for that matter, am or sitting. Many words don't fit this referential or descriptive theory of meaning. So, if meaning is not referential description, what is it? Well here we're going to take our cue from Ludwig Wittgenstein, the great 20th century Austrian philosopher, who argued that meaning is use. If you want to understand the meaning of the word hello, you don't look for some object that it refers to, you ask how is it used and the answer is obvious, it's used to greet people. If you want to understand the meaning of the question, where's the library? The answer is, well, that question is used to inquire about the library, to ask where the library is. If you want to understand the meaning of an imperative like, gimme a pizza. Then that is a way of ordering a pizza. You're using that phrase to order a pizza. So the meaning of the phrase is given by the way those words are used in normal situations by competent speakers of the language. Now, this point about meaning being used is very important to the language of argument. As we saw the word not does not refer to an additional object and the same goes for the word and. When you say, I am sitting in the chair and I am in the office, the word and doesn't refer to an object either. So if we want to understand what the word and is used to do then we have to think about what people do with it. And what they do is they conjoint different sentences. They don't add an extra object or an extra fact, they just conjoin sentences and form a whole sentence out of two parts, each of which was a sentence to begin with. Of course, the word and is not always used to conjoin sentences. We can say things like Roberto and Olivia went to Sao Paulo together. And Roberto's not a sentence, Olivia's not a sentence, they're people, not sentences. And there weren't three things that went to Sao Paulo together. Roberto, Olivia, and this third thing and, whatever that is. Still, the word and is used to conjoin. In this case, it's used to conjoin things or people. In the previous examples it was used to join, conjoin sentences. But if we want to know what the word and means, we shouldn't be looking for some object that it refers to. Instead, we should be describing how it's used and what it's used to do. Namely, it's used to conjoin. And when we look more closely at the uses of language, we see that language is used in a lot of different ways. Use is diverse. Just take a simple example. I'd like to give you a little piece of personal advice. You ought to floss your teeth every day. So what did I just do? I uttered a bunch of words. I made physical motion in the air. But in addition, those words were meaningful, you ought to floss your teeth every day. Each of those words is meaningful in the language, and I put them together in an order that was grammatical, so the whole thing makes sense. When you make a meaningful utterance like that, we're going to say you perform a linguistic act and there's a linguistic level of the use of language that we will study in one lecture, the next lecture. But in addition, when I said you ought to floss your teeth every day, I also gave you a piece of friendly advice. I advised you. And notice that, even if you don't follow my advice, I still advised you. And, if you don't follow my advice and your teeth rot out, then I can say, look, you should've listened to me. because I advised you to floss your teeth every day. So, the speech act level occurs even when it doesn't affect your actions at all. That's the second level of use of language, the speech act level, and we'll talk about that in more detail two lectures from now. The third level of language has to do with the production of certain effects. Maybe when I say, you ought to floss your teeth everyday, I persuade you. And what that means is I bring about a certain effect on your behavior or your thought or your attitudes. Well, that's what we're going to call the conversational level. And conversational acts are the acts of bringing about those effects and persuasion is one example. So now we have three levels of language. We have the linguistic level, which is the meaningful utterance, producing a meaningful utterance. We have the speech act level. Advising is a nice paradigm of that, which can be accomplished even if you're not persuaded. And we have persuading you, which is the conversational level. So there's the linguistic level, the speech act level, and the conversational level. And each of these levels will be explored in more detail in one of the next three lectures. But here's a little warning. And you have a choice. The material in the next three lectures is a little bit more abstract and difficult than some of the things we've been through so far. Now I think it's fascinating. We're going to try to make it fun. And it's really important to understand how your language works. But it's not absolutely essential to the things that we're going to cover in the rest of this course. So it's up to you. You can listen to these three lectures if you want and there will be some exercises throughout those lectures that will test your understanding, but none of that material's going to be on the quiz. So you can listen to the next three lectures, and I hope you do, and I hope you enjoy them, but you don't have to in order to be able to go through the rest of the course and do well on the quiz at the end of this part.