This paper builds in many ways upon ideas in Kaplan's paper "Dthat". The fundamental question is whether Frege can give a reasonable account of demonstrative reference.
Perry begins by explaining certain key doctrines to which he takes Frege to have been committed:
- If A understands S and T, and accepts S as true while not accepting T as true, then S and T have different senses.
- If S is true and T is not, then S and T express different thoughts.
- If "A believes S" is true, and "A believes T" is not, then S and T do not have the same indirect reference.
- S and T have different senses iff they express different thoughts iff they have different indirect references.
What Perry will argue is that not all of these claims can be true together when the sentences in question involve indexicals, such as "I" and "today". Claims (1) and (2), and the identification in the first part of (4), are what will matter.
Perry calls all of the expressions in which he is interested "demonstratives", but it is standard nowadays to reserve that term for expressions like "that" and "this dog". Words like "I", "here", and "yesterday" are instead known as indexicals.
On pp. 477-8, Perry notes (and this is a point Frege makes himself) that sentences do not always express thoughts. Some sentences are "incomplete" in themselves, and what thought they express will vary from case to case. The example Perry gives is "Russia and Canada quarreled", which is 'incomplete' as to the time at which the quarrel is alleged to have occurred. The sense the sentence has in its own right, then, is similarly 'incomplete', and the sense an utterance of it expresses on any given occasion will depend upon how that sense is 'completed'.
Frege, Perry says, thinks of context-dependent utterances in the same way: the sentence uttered—e.g., "Russia and Canada quarrelled today"—does not itself express a thought, but only does so in light the conditions under which the utterance is made. So "today", together with the circumstances of utterance, must provide a "completing sense". And the problem, as Perry sees it, is that this does not seem possible, given Frege's other views about sense.
If "today" always had the same sense, then different utterances of "Russia and Canada quarrelled today" would always have the same sense and so express the same thought. But they can't, since different utterances of that sentence can have different truth-values and so, by (2) above, must express different thoughts. Hence, it must be that "today" expresses different senses when uttered on different days.
Now something about "today" does change from day to day, namely, which day an utterance of it would refer to: It is a feature of what "today" means that any given utterance of it will refer to the day on which it is uttered; similarly, it is a feature of what "I" means that utterances of it refer to the person who utters it. Perry calls this rule mapping utterances to referents the role of the word. (It is clearly of a piece with Kaplan's notion of character.) The important point here is that the role gives us only a reference. But Frege needs it to do more—or, at least, he needs something to do more: Not just a reference but also a sense must somehow be provided on any given occasion of utterance. The question is how this is supposed to happen.
Perry considers three options open to Frege.
The first is to take the sense associated with a given utterance of "today" just to be its role. The problem with this proposal is that the sense of a given utterance of "Russia and Canada quarrelled today" will then always be the same, and that violates (2) above, as said already.
What is new in this discussion is the idea that sentences can have roles, not just indexicals. And whether that will help Frege or not, one might wonder if it's a useful extension of the notion. Perry's presentation of the idea is a bit compressed. Can you spell it out in more detail?
The second option is to introduce a somewhat coarser-grained notion of a thought. Perry explains this notion in terms of what he calls "informational equivalence", but one might better think of such thoughts as a hybrid of Fregean and Russellian ideas. Consider the sentence "Tony loves Alex". Frege would have us think of the thought expressed by such a sentence as something like:
<sense of 'Tony', sense of 'loves', sense of 'Alex'>
Russell would think of the proposition expressed as:
<Tony, loving, Alex>
The proposal under consideration is that Frege might take the sense of "I love Alex", as uttered by me, to be:
<RH, sense of 'loves', sense of 'Alex'>
The role of "I", though it doesn't get us a sense for my utterance of it, does at least get us a referent, and so will get us one of these hybrids.
The main objection Perry raises against this suggestion is that it violates principle (1) above. The example he gives is the now famous Enterprise example.
Painting of Frege by Renee Bollinger.
You can also get it on a mug, or tote bag, or clock, or...,
and there are many other philosophers to choose from, as well!)
The corresponding view in this case would have both utterances of "That ship is an aircraft carrier" express
<Enterprise, sense of 'aircraft carrier'>
But, as Perry notes, one could believe one and not the other, so the utterances need to have different senses.
Perry gives an additional example, involving "today", but (to my mind) it is not a terribly convincing. Can you think of better examples involving other indexicals, e.g., "here", "now", "you", "there"? Is it possible to come up with such an example for "I"?
The third option, then, is to try to find some way to let the sense expressed by an indexical on a given occasion vary. Perry supposes that, whatever the sense is on a given occasion, it has to be expressible by some description that picks out the right day. The central objection to this move is that there simply isn't any non-indexical description that will have the same sense as a given utterance of "today". For any non-indexical descrition of a day "the F", it seems one could coherently doubt that today is the one and only one day that is F. If so, then "the F" and that utterance of "today" must have different senses. Similar problems arise with other indexicals, such as "I": For any non-indexical description "the F" of me, I could coherently doubt whether I am the F.
As Perry notes, this sort of point is originally due to Hector-Neri Castañeda. See the references in note 5. Perry himself develops it in more detail in his paper "The Problem of the Essential Indexical", Noûs 13 (1979), pp. 3-21 (JSTOR).
The objections Perry brings against this view—especially the first two—should remind you of objections Kripke brought against the description theory of reference-fixing. Which ones?
Perry goes on to suggest, in section II, that Frege was led by these problems to the view, which he expresses in "The Thought", that the sense each of us associates with our own utterances of "I" is primitive, idiosyncratic, and incommunicable.
Perry expresses some consternation about how this might be true, largely because he continues to insist that, whatever this sense might be, it must involve some description I have of myself. As we'll see with Evans, that is questionable. That does not of course mean that Frege's suggestion is easy to understand. Again, Evans will try to make some sense of it.
Perry's main worry about this proposal is that it's hard to see how to extend this idea to other cases, such as "now". Or, rather: It's clear enough how to do so, but it implies that "Frege will have to have, for each time, a primitive and particular way in which it is presented to us at that time, which gives rise to thoughts accessible only at that time, and expressible, at it, with 'now'" (p. 491). And Perry thinks that isn't plausible at all.
Perry doesn't say much about why he thinks that claim is implausible. Why might one?
In section III, Perry sketches an alternative to Frege's treatment. The sense of a sentence, as Perry wants us to think of it, is not the thought the sentence expresses; rather, it helps to determine that thought. So Hume can 'entertain the sense' of the sentence "I am British" and thereby have a belief with the content:
<Hume, being British>
Heimson, on the other hand, cannot have a belief with this same content by entertaining that same sense, but only by entertaining some other sense. Senses, for Perry, are thus roles, as suggested in the first of the options he offered Frege; and thoughts are the hybrids presented in the second option. But Perry doesn't have the same problems Frege does, because he is not committed to (1)–(4) above.
Perry is clear that he wants to reject (4): the identification of senses with thoughts. What should he say about (1)–(3)?
On p. 494, Perry briefly discusses the way in which senses and thoughts, as he understands them, do and do not figure in the explanation of people's behavior. How do the views he expresses here relate to those in Loar's paper?
On pp. 495-6, Perry considers how his view might handle the sort of case Frege uses to motivate the distinction between sense and reference. In his example, Mary says in the morning "I believe that is the Morning Star" and in the evening "I believe that is not the Morning Star". How does Perry's view do with a slightly different example, in which Mary says in the evening, "I do not believe that is the Morning Star"?