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 arguments 
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 going to 
express the meaning of the sentence, 
because that going that's going effect 
whether the premises justifies the 
conclusion of or, whether they explain 
the conclusion, and so we need to focus 
on those rules of language which that in 
particular deal with the meanings of 
words 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. 
and 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 were 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's 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, a 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, give me 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 conjoin 
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. 
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 everyday, 
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 every day, 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 it, 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 and 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 materials 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.