When you use the word ``I" it designates you; when I use the same word, it designates me. If you use ``you" talking to me, it designates me; when I use it talking to you, it designates you. ``I"' and ``you'' are indexicals. The designation of an indexical shifts from speaker to speaker, time to time, place to place. Different utterances of the same indexical designate different things, because what is designated depends not only on the meaning associated with the expression, but also on facts about the utterance. An utterance of ``I" designates the person who utters it; an utterance of ``you" designates the person to whom it is addressed, an utterance of ``here" designates the place at which the utterance is made, and so forth. Because indexicals shift their designation in this way, sentences containing indexicals can be used to say different things on different occasions. Suppose you say to me, ``You are wrong and I am right about reference," and I reply with the same sentence. We have used the same sentence, with the same meaning, but said quite different and incompatible things.
In addition to ``I'' and ``you'', the standard list of indexicals includes the personal pronouns ``my'', ``he'', ``his'', ``she'', ``it'', the demonstrative pronouns ``that'' and ``this'', the adverbs ``here'', ``now'', ``today'', ``yesterday'' and ``tomorrow'' and the adjectives ``actual'' and ``present''. This list is from David Kaplan [1989a], whose work on the ``logic of demonstratives'' is responsible for much of the increased attention given to indexicals by philosophers of language in recent years. The words and aspects of words that indicate tense are also indexicals. And many other words, like ``local'', seem to have an indexical element.
Philosophers have found indexicals interesting for at least
two reasons. First, such words as ``I" and ``now" and
``this'' play crucial roles in arguments and paradoxes about
such philosophically rich subjects as the self, the nature
of time, and the nature of perception. Second, although the
meaning of these words seems relatively straightforward, it
has not been so obvious how to incorporate these meanings
into semantical theory. I will focus on the second issue in
this essay and, even with respect to that issue, discuss
only a few of the many topics that deserve attention. Among
other things, I won't consider tense, or
plurals
, or the relation of indexicality to
anaphora, or
Castañeda's concept of quasi-indication. I'll focus on the words
Kaplan listed, and among those on singular terms.
In section 2 I fix some concepts and terms. In section 3 I develop a treatment of indexicals that I call the ``Reflexive-referential theory''. It is based on an account by Arthur Burks, and also incorporates ideas from Reichenbach, Kaplan and a number of other authors.