1.3.2. Some complications
Probably no one ever believed that the simplified model of language we have been considering was entirely accurate. But it, or something like it, was until recent decades the working model most logicians used for thinking about the function of language. Around the middle of the 20th century, philosophers became interested in a number of features of language that suggest this picture is inadequate; and these features have been incorporated into a number of richer models of language. The norms of deductive logic that we will study do not rest on the richer structure of these new models, so we will not consider such models in detail. But some of the further features of language that they attempt to capture are intertwined with those we will study, so we need to take some time now to disentangle ourselves from a few of these features once and for all and to lay the groundwork for disentangling ourselves from others at later points in the course.
The complicating phenomena that we need to consider have come to be studied under the rubric of pragmatics. This term was originally introduced (by Charles Morris) as an alternative to semantics in order to distinguish issues concerning the relation of language to its users from the issues concerning the relation of language to what is spoken of. The use of the term pragmatics is no longer closely tied to this definition, and I know of no definition that really captures the way it is now used. Probably the best way to understand current usage is to consider some commonly agreed examples of pragmatic phenomena. I will note four of them.
The first two concern aspects of meaning that are not captured by the idea of truth conditions.
Sentences are not always used to express propositions. When a sentence is used to express a proposition, the question of its truth value is a significant one. But not all sentences have truth values or raise questions of truth value. And even when a sentence does have a truth value, its truth value may not be its most important feature. There are ways of using sentences besides assertion—questions and commands are only the most basic examples of other speech acts—and the way a sentence is used is one aspect of its meaning. The term force is often used for this aspect of meaning.
The information we derive from the use of sentences is not limited to what follows from assuming them to be true. Even assertions can be expected to have properties other than truth, and the assumption that an assertion has a given property can be the basis for deriving information from it. In short, there can be forms of accommodation associated with properties other than truth. This produces the phenomena of implicature, in which a sentence suggests more than it says. Even when everything a sentence literally says is true—so its implications are all true—an additional false suggestion, a further implicature, can make it misleading.
These two complications suggest that propositions are not quite as central to the use of language as the simple model suggests: sentences do not serve merely to convey the propositions they express.
Several further complications concern the relation between sentences and propositions.
The proposition expressed by a sentence may vary with the context in which it is used. For example, there is no way to judge the truth value of a sentence like I put that here yesterday when it is taken out of context. This dependence on context is due to various phenomena known collectively as indexicality or deixis. These terms are etymologically related to terms for pointing, and the functions of words this and that are paradigm examples of such phenomena. The term character has been used for the way the proposition that is expressed by a sentence depends on the context of its use.
Even with regard to a given context, a sentence may not express a fully determinate proposition. This can happen for a couple of reasons. First, the meaning of vague terms like small and hot will vary with the context; and even in a given context there will be no sharp delineation of the cases where they apply truly. That means that the content and coverage of a sentence like That’s hot may not be divided by a sharp line, and some possibilities may lie in a gray area between them.
A second reason for indeterminacy in the proposition expressed by a sentence is that there may be preconditions for the sentence to have any truth value in a given possible world. Such a sentence will be neither true nor false at a possible world that does not satisfy these preconditions, which are said to be semantic presuppositions of the sentence. A common example of this is a sentence that contains terms that may refer to nothing if the facts are not right. For example, the question whether John’s car is red is or is not the case has no good answer when John does not in any sense have
a car, so him having a car is something that John’s car is red presupposes.
These phenomena all constitute ways in which the truth value of a sentence may depend on factors affecting the meaning of component vocabulary. And this dependence can take two forms: the truth value may vary as these other factors do or it may fail to exist if they are not present.
The force, the implicatures, the character, the degree of vagueness, and the presuppositions of a sentence are parts of its meaning in the fullest sense of the term, and we will consider them each at least briefly to distinguish them from the narrower sense of meaning that will be our focus. It is easy to disentangle our topic from some of these phenomena but others require more detailed consideration, and some forms of entanglement are more likely to trip us up later than are others. As a result we will consider some of these sorts of meaning only to dismiss them quickly, and we will set others aside without completing disentangling ourselves from them. Implicature is the only one of these aspects of meaning that we will need to pay much attention to in later parts of the course.