Kaplan’s Character

As noted above, Kaplan’s character is a level of meaning associated with indexical expression types that encodes their repeatable, invariant semantic properties. As such, character seems like a promising candidate for providing the basis of the standard interpretation of such expressions in Stalnaker’s framework. However, interlocutors can’t update the context set with an expression’s characterper se for two reasons, one

technical, and one substantive. First, the character associated with a given indexical is a function defined in terms Kaplan’s context of use, and not itself a proposition. For

example, before yielding propositional content, a sentence such as ‘I am bald’ must first be provided with the value of the agent parameter of the relevant context of use.

Until then, it cannot properly update the context set by way of intersection.

More importantly, however, interlocutors don’t know which possible world they inhabit, and so don’t have access to the appropriate context of use corresponding to

their situation. When it comes to communication and interpreting the speech of others, “the contextual features on which what is said depends must, in any appropriate speech act, be presumed to be available to the addressee” (Stalnaker, 2014, p. 217). Whereas Kaplan’s character for ‘I’ yields the (actual) individual who is speaking (regardless of what anyone presupposes about said individual), Stalnaker’s framework requires that the rule associated with ‘I’ yield the individual the interlocutors presuppose to be speaking (regardless of who is actually speaking). So character, if it is to provide

the standard interpretation, needs to be redefined in terms of something other than Kaplan’s context of use.

The obvious candidate here is the common ground, the information mutually

presupposed by – and hence mutually presupposed to be available to – the parties to a conversation. Thus Stalnaker (2014) suggests,

to stay with the intuitive idea motivating Kaplan’s character/content seman- tics, we would take character to be a function from the C[ommon]G[round]- context (rather than the K[aplan]-context) to content (p. 215).

More specifically, we should redefine character as

a function whose argument is an element of the CG-context [. . . ] and whose value is the feature in question (a world, an agent, or an addressee) (p. 215).17

Rather than a function from a context of use to an individual, then, character will

be a function from a possible world (in thecommon ground) to an individual in that

world (speaker, times, location, etc.). This definition has the result of delivering the individual the interlocutors take to be the speaker, say, rather than the actual speaker as the content of an utterance of ‘I’. The distinction is, of course, innocuous when the individual the interlocutors presuppose to be the speaker is in fact the actual speaker (e.g., c1=c2), but the redefined character also covers cases where the interlocutors are

mistaken about, or unaware of, the identity of the speaker (e.g., c1 ̸=c2).

Which proposition, then, is associated with a sentence containing an indexical according to the redefined character, the proposition relevant for updating the context set? In the case of, e.g., ‘I am bald’, it is the proposition that is true in each world

in the common ground in which the speaker in that world is bald, and false in each

world in the common ground in which the speaker in that world is not bald. More

generally, an indexical sentence sensitive to feature x (speaker, time, location, etc.) of

the form ‘x is F’ will express a proposition that is true in each world in thecommon ground in whichx in that world is F, and false otherwise. In other words, each sentence

containing an indexical will express a diagonal proposition. With our redefinition of character, then, we have a candidate standard interpretation in the form of the diagonal proposition, which can update the context set by way of intersection.

Stalnaker originally introduced diagonalization as a way of treating cases where the content of an utterance is, on a standard (Kaplan-style) semantics, a necessary truth

17 _{Stalnaker makes these remarks while discussing cases such as ‘actual’, ‘I’, and ‘you’ where Kaplan’s}

semantics “appeals to a feature of “context” that is not available in the common ground (such as the world of the context, or in cases where the identity of the speaker or addressee is in question, or “at issue”, the agent or addressee of the context” (p. 215). Nevertheless, it is clear that such a redefinition of character will generalize to all indexicals.

4.4 Re-evaluating the Relation Between the Two Notions of Context | 125

or a necessary falsehood, and hence does not eliminate worlds from the context set,

precisely the antithesis of the purpose of assertion. Such cases are, in a sense, the result of an under-generation of (assertoric) content in the Stalnakerian framework. As we

saw above in section 4.3.3, a related problem arises in the case of sentences containing indexicals, where a straightforward application of Kaplan’s semantics to the members of the context set (each a distinct context of use) over-generates (Kaplanian) content.

In such cases there is more than one proposition that could update the context set, but

the audience is in no position to tell which one it should be. On the current proposal, taking the diagonal proposition as the assertoric content of the utterance ensures that a single proposition is expressed in each world of the context set, and in accord with the purpose of assertion, eliminates some, but not all, of those worlds.

Notice that on this way of understanding things, diagonalization is no longer a result of reinterpretation, but rather straightforward interpretation. More recently,

however, Stalnaker (2014) has suggested this is the correct way to understand the content of assertions in his framework:

if we want to identify a proposition that is the assertoric content of an utterance [. . . ] [the] diagonal proposition comes closest to what we want for the following reason: the role of assertoric content [. . . ] is to determine which are the possibilities to be eliminated from the context set when an assertion with that content is accepted (p. 216-217).