Now we can combine three semantic elements to explicate the full mean-ing of an indexical sentence as used on an occasion. The first is character, the second is content, and the third corresponds to the sameness of sense that exists between “today” and “yesterday.” Let us call this third layer information. The same information is conveyed by saying “Today is cold”
on D1 as would be conveyed by saying on D2 “Yesterday was cold.” The speaker acquires the information from his sense experience on D1 that the day is cold and that information is stored in his memory. On D2 when he says “Yesterday was cold,” he is merely referring back to the information he acquired from the previous day that is stored in his memory. The speaker has the same piece of knowledge acquired the previous day but he expresses it by using different words. Therefore, the same information is in the speak-er’s mind over the two days and he expresses it using these two different sentences. This notion of information is not reducible to either character or content. Content is too wide a notion and does not capture the exact meaning of what the speaker says. To avoid confusion, we might rename Kaplanian content real-world correlate. The real-world correlate of the index-ical is the object to which the speaker refers. We can still regard this as a
component of the proposition expressed. We could also naturally rename character perspective. Perspective incorporates the two different temporal perspectives the speaker has on the given day—as present and as past. Let us insert this into the proposition too. The same information is expressed from two different perspectives. It is information about the same real-world correlate. We should not say that there is only the real-world correlate and the perspective, because then we could not understand the relationship between “today” and “yesterday” in the right way. The information is pre-served over time and then expressed from two different perspectives, but the information is more like a cognitive state than a real-world correlate.
This can be bundled into the proposition along with the other two ele-ments. None of these propositional components determines any of the oth-ers, so none is redundant. If we think of the informational component as descriptive, which is natural, then we shall not insist that the descriptive information determines a particular day—it might be available on other days too (so it is not equivalent to reference-determining Fregean sense).
We have three irreducibly distinct and indispensable semantic ingredients:
real-world correlate, perspective, and information.
According to this triple-layer semantics, it turns out that everybody is a little bit right and little bit wrong about this subject. Kaplan is right to intro-duce character and content but wrong to think that character and content are all that is required. Evans believes that only Fregean sense is needed. He is right to think that there is something common to “today” and “yester-day” but wrong to suppose that nothing separates them (character). Evans leaves no room in his theory for this semantic difference: he needs charac-ter in the full meaning of an indexical utcharac-terance as well as sense. The same information is indeed expressed by these two words on successive days, but each term has a different conventional meaning. Kaplan and Evans both offer incomplete theories because they each need something from the oth-er’s arsenal to fill out the full account of indexical meaning. We need both character and content, but we also need to recognize that indexicals with different character can have something in common (what we have been calling information) that is not reducible to content. The next task would be to inquire more closely into what this notion of information amounts to (a task we shall leave for homework). All we can say now is that information is an epistemic notion: it relates to what someone knows. What is clear by now is that the topic of indexical semantics bristles with complexity and difficulty, and no current theory has all the pieces worked out.
7.1 Background
Our earlier discussions of indexicality will help us to understand the force of Hilary Putnam’s arguments in “Meaning and Reference.” For indexical expressions, the classic theory of descriptive intensions that determine extensions looks highly implausible—as Kaplan argues. The meaning of an indexical when used on an occasion is not equivalent to a definite descrip-tion of the object or type of object referred to. As Putnam notes toward the end of his paper, two people can use the word “I” to refer to themselves even if they don’t differ in the descriptions they would ascribe to them-selves; so the difference of reference cannot stem from uniquely identifying knowledge possessed by the two speakers. Here context plays an indispens-able reference-determining role—and not simply what occurs descriptively inside the speaker’s mind. What you refer to can depend on who and where you are, not just on what you think—it depends on external context, not internal descriptions. That is, indexical reference is fixed externally by the speaker’s objective context, not by what he has in his mind subjectively.
This is in contrast with descriptive reference, which is context indepen-dent, because here the speaker’s internal concepts do suffice to fix what he refers to. Thus externalism is correct for indexical reference, but internalism is correct for (pure) descriptive reference—as with “the first dog to be born at sea.” In the case of “I” we just need to know who is uttering the word to determine its reference, not what that person thinks about his reference.
Putnam’s focus is on natural kind terms like “water,” “aluminum,” and
“tiger”—words that stand for types of object found in nature—not words for human artifacts like “table,” “computer,” or “president.” He wants to know what these words mean, particularly how they determine their reference. At
the end of his paper he says, “Our theory can be summarized as saying that words like ‘water’ have an unnoticed indexical component: ‘water’ is stuff that that bears a certain similarity relation to the water around here” (note the indexical “here”). In other words, the semantics of natural kind terms mirrors the semantics of indexical terms. Such terms do not conform to the classic Fregean model of the definite description and its reference. Putnam tells us that it used to be thought that for any meaningful expression there is an intension that determines the extension in every possible world, and that when a speaker understands the term she grasps the intension of the term.
But he argues that this is not true of natural kind terms—we do not under-stand them by grasping such intensions. We underunder-stand them in the same way we understand indexicals, where context plays an indispensable role.
Putnam puts this by saying that the psychological state of the speaker is not the sole determinant of the reference of her terms—that is, internal psychol-ogy does not determine a speaker’s reference. He thus rejects the old view to the effect that a speaker’s reference can be extracted from what is in her mind as she speaks. We shall now examine his arguments for this conclusion.