Assignment for this week |
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Read chapter one carefully. Except for Section 1.2.1. Read Section 1.2.1 carelessly. Try not to remember any of the terminology introduced there. Do the exercises introduced in this lecture with Exercise heading. |
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Sense vs Denotation |
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An expression like the president uttered last week denoted a particular individual in the world, George Bush. Uttered today, it denotes Barak Obama. Uttered in 1993 it denoted Bill Clinton. Nevertheless the meaning or sense of the expression the president hasn't changed. Modulo the elimination of a few voters in a few Florida and Ohio counties, the way of determining what the expression the president denotes is the same. Important terms:
Now if we say the Republican Senator from Arizona who was a candidate for president in the election of 2008, that has a different sense and a different denotation. It has a different denotation because it has a different sense. Expressions with different meanings can pick out out different things in the world. We say the sense determines the denotation. (though we'll modify this slightly below).
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Ways of Defining |
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Although in the previous discussion we focused on the expression the president, we can narrow our attention to the lexical item president. What exactly the word the does we're not ready to discuss yet, but clearly the word president bears primary responsibility for the fact that the expression the president picks out Barak Obama. Since we're interested in meaning, let's talk about how the meaning of a word like president is defined:
Note: A word may have many senses, even when we control for syntactic category. The verb bank has several senses:
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Exercise: Definitions |
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Both kinds of definition have their problems and won't really play a role in our theory. However they are useful in identifying some of the intuitions that go with sense and denotation. Ostensive definitions try to pick out parts of the denotation of a word; definitions by paraphrase try to pick out the sense. Also we saw that in some sense definitions, of either kind, aren't complete. But it's not clear that complete definitions are the business of semantics. This is the subject of exercise one:
Exercise one: Consider the following principle of Generative linguistics.
Part A: Are speakers are able to speak and understand without knowing complete definitions of the words they use? Give 3 plausible examples of successful communications in which speakers aren't able to produce complete definitions of the words they use. Hint: There are lots of ways to do this but use at least one simple example using what are called natural kind terms. A natural kind term denotes some natural kind of thing in the real world. Examples are dog, cat, tree, dolphin, Border Collie. You might also consider using some non-natural kinds in your discussion. Non-natural kinds are kinds that are human-made.Chair, telephone, computer are examples. Don't use any of these exact words as your examples. Also, don't use technical language. In other words, I don't know the definition of the term chondromalacia (something bad that can happen to a knee) but it's also pretty clear that me trying to communicate with this word is fraught with peril. So what we're interested in is cases where you don't know the exact definition of a common word but you can still communicate with it effectively. Part B: Address the following issue in your discussion. When we do syntax we concede that speakers are not able to articulate what a subject or a constituent is, but we argue that they have tacit knowledge of these things on the basis of the evidence of their grammaticality intuitions. Thus we argue that speakers know that the book about Lincoln is a constituent in
Can we argue the same about complete definitions? That is, can we argue that speakers DO have complete definitions in their heads but that the knowledge is tacit and they are unable to articulate these definitions? Finally, one way of answering this question is to take the position that people can know the meaning of a word without having a complete definition in their heads. But if you take that position you need to say what it is that a competent speaker knows when he knows the meaning of a word. You don't have to come up with a precise definition of what they know. Take a stab at an operational definition. An operational definition is one that works most of the time in practice without settling all questions about all logical possibilities. Operational definitions can be tremendously useful, but they are tricky. An operational definition of an eclair is what they bring you when you order an eclair. You can get pretty far with this operational definition, identifying lots of eclair instances, but remember, with this definition you are in no position to complain when they bring you a Napoleon. |
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Denotation |   |
Above we used the term denotation to pick out what a noun phrase referred to. In the special case of a noun phrase this is also called its reference. We use the term denotation for more than just noun phrases. For all kinds of expressions, the part of reality the expression picks out is its denotation.
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Context |   |
We said above sense determines denotation. This can't be quite right. First of all the expression the president denotes different persons on different occasions of use. So it's at least the case that sense + time of utterance determines the denotation. In other words, at least one other thing besides the sense is required to determine the denotation. But also we have the following, which is perfectly fine even I utter it right now:
So context can fill in the time of the presidency we are talking about. Of course context has been filling more stuff than time in all the examples we've been talking about:
So we have the following:
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Different sense Same denotation |
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Expressions with very different senses can have the same denotations and this is largely unpredictable linguistically, because it has to do with the weird and wonderful way the world turned out. Some expressions with different senses and identical denotations:
Speculation: Substitutivity of Identicals (Leibniz's Law)
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Somewhat Mathematical |
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Substitution of Identicals again:
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Theoretical Importance: Sense or Denotation? |
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The preceding examples should pretty much have convinced you that what's important for the theory of semantics is sense, not denotation. Denotations vary at the whim of the electorate and the Gods of baseball. What matters linguistically is senses! The trouble with this conclusion is that there's lots wrong with senses as well.
Denotations, despite their limits, are clearer, For example, the principle of substitutivity gives us a very powerful handle on denotations. We have clearer intuitions about what they are, how they change. Still there is the problem of the evanescence of denotations. Consider dog again. We said its denotation is:
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Summary |
We are in search of an object of study for semantics We want a substitute for meanings, because we don't know what they are. Two criteria
Results thus far:
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Intension A theoretical Construct |
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Solution: We're going to extend the way we use the term denotation by means of a theoretical construct. Consider dog. At any instant of time there is a certain set of individuals that is the set of dogs. If the world were only slightly different than it is, there would be a slightly different set of dogs. Thus the denotation depends not only on the sense but also on the way the world is, or as we shall say, on what world we are in. So our theoretical construct is this: there is a set of worlds we call the set all possible worlds, and the denotation of dog varies from world to world:
So denotations are double-layered. A denotation is an intension that picks out an extension at each possible world. These examples are incomplete. The set of all possible worlds really needs to cover all possible ways the world might differ from the way it is. With respect to the word dog the set of possible worlds needs to provide with all possible individuals that might be a dog, and at least one world for each distinct possible set of dogs. That's a lot of worlds.... |
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Denotations for sentences |
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First, what should the extension at a particular world be? To answer this question we will return to the principle of substitutivity of identicals. A sentence is a complex expression with a denotation. Let's see what happens when we substitute different expressions with the same denotation into it:
But what is it that is the same? Not the meaning. In a different world in which the same guy wasn't Mr Universe 1970 and the governor of California 2005, these sentences might have different truth-values. But the meaning would still be the same. But here is the key point: In any world in which the denotations of
So it is the truth-value of a sentence that functions like a denotation . It is the truth-value of a sentence that stays the same when expressions with identical denotations are substituted into it. [Frege's argument] So the extension of a sentence will be a truth-value (either true or false); and the intension will be a table that tells us the truth value in each world. The extension at each world will depend on the extension of expressions inside it at that world. |
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Example: Denotations |
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And suppose that this is the way it is with grinning in our 4 worlds:
And consistent with these we have the following intension:
Note: I differ slightly from the text in saying that intension of a sentence is a table giving the truth value at each world. The text just says the intension of a sentence is the set of possible worlds at which the sentence is true. These ideas are equivalent: You can construct the table from the set, and vice versa. More on this later. |
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Sentence Meaning |
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The wrong theory: the meanings of the words determine the meaning of a sentence. Problem:
Pick from among the following nouns for A,B,C:
Pick from among the following transitive verbs for X,Y.
Many sentences with MANY different meanings:
Sentence Meaning = Lexical Meaning + Structural Meaning |
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A job for Syntax |
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Determine structural meaning! That's what it's for. That's why there IS such a thing as syntax! You finally know. |
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Compositional Semantics |
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A compositional semantics for a (fragment of a) language is a formal account of how the meaning of the whole is composed of the meaning of the parts. Given what we just noted about structural meaning, this means that a compositional semantics combines lexical meaning and structural meaning to compute the meaning of sentences. It does this by providing rules for interpreting strcutures. More technically, we have just committed to a denotational theory, where denotation means intension. Thus our theory needs to account for how the intension of the whole is composed out of the intension of the parts. But in working out the details, it quickly becomes clear that not every word has a natural intension:
For example, the extensional rule for and (discussed in Section 1.3.4, (38), (39)) is:
Thus, all the rule has to do is tell us under what circumstances the sentences is true or false (in terms of the truth values of the sentence's parts). A similar rule for or:
The intensional treatment of and has to define an intension; that is, for every world, it has to tell us under what circumstances the conjoined sentence is true in that world, and under what circumstances it is false:
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Exercise 2: Compositional Semantics |
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A small compositional semantics. The exercise is in the section labeled "Exercise". |
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Summarizing |   |
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