In this paper, Evans responds to Perry's criticisms of Frege and develops a Fregean account of the senses of demonstratives and indexicals.
Evans first recounts the arguments in Perry's paper, noting that the crucial assumption is "that a Fregean sense of any singular term must be either the sense of a definite description or 'intimately related' to such a sense" (p. 292). He then goes on, in the second section, to elaborate a conception of sense that he claims has no such commitment.
Evans's discussion is extremely abstract, but the central idea is fairly easy to understand. Consider the terms "Hesperus" and "Phosphorous". To understand such a term, Evans says, one must know what it refers to: "an understanding of the language must be capable of being regarded as involving knowledge of the semantic values of expressions" (p. 293). If so, however, then one might worry that understanding these two terms would involve the very same thing: knowing that they refer to Venus. But, Evans says, "Frege's idea was that to understand an expression, one must not merely think of the reference that it is the reference, but that one must, in so thinking, think of the reference in a particular way" and the sense of the expression is the particular way in which one must think of its referent to undrestand that expression (p. 294). So there is a particular way one must think of Hepersus (=Venus) in order to understand the expression "Hesperus", and a different way in which one must think of Phosphorous.
Evans says that, at this stage, we may leave the notion of a "way of thinking" at an pre-theoretical level. But he also indicates that he has a more sophisticated notion in mind.
If the intuitive notion needs to be supplemented, we can appeal to the general idea of an account of what makes it the case that a thought is about the object which it is about; two people will then be thinking of an object in the same way if and only if the account of what makes the one person’s thought about that object is the same as the account of what makes the other person’s thought about that object. (p. 294)
Evans does not say much more about this idea yet, but it will become important later.
A particularly important idea here is that, on this conception, sense is, in a certain respect, not independent of reference: "If sense is a way of thinking of reference, we should not expect to be given the sense of an expression save in the course of being given the reference of that expression" (p. 294). This leads to the idea that it is perfectly consistent with Frege's ideas to recognize what Evans calls "Russellian singular terms": terms that could not have the sense they do without also having a referent (p. 296). And that idea will play a crucial role in what follows.
Evans tends to talk of Russellian terms as ones that could not have the sense they do without having some referent. But most interpreters have concluded that what he really means is: without having the very referent they do. So the senses of Russellian terms are specific to a particular referent.
On pp. 301-3, Evans argues in detail that there is no argument from the claim that terms with the same referent can have different senses to the conclusion that those terms are non-Russellian, i.e., that they could have the sense they do without having a referent at all. The issue is whether senses, as Evans understands them, can do the work that Frege needs them to do: explain differences of cognitive value. Evans says that they will, so long as his principle (P) is satisfied:
If the account of what makes a subject’s thought T1 (about x to the effect that it is F) about x is different from the account of what makes his thought T2 (about x to the effect that it is F) about x, it is possible for the subject coherently to take, at one and the same time, different epistemic attitudes towards the thoughts he entertains in T1 and in T2. (p. 301)
Evans claims that (P) is "very plausible" and, more importantly, that there is no reason to believe that the only accounts that could satisfy (P) would involve the subject having some identifying description of x.
The evaluation of principle (P) obviously depends, to a large extent, upon how the notion of an "account of what makes a thought about the object it is about" is spelled out, and we'll get more help with that notion later in the paper. But Evans does seem to think that, even absent such details, (P) is plausible. Is it? Why or why not?
In section III, Evans begins his positive account of what the sense associated with a given utterance of "today" might be. Evans's first point is that of course there is a particular way one must think of a given day in order to be thinking of it as 'today': not any way of thinking of that day will do. This does not by itself help us to understand what way that is, or what 'ways of thinking' are, in general. But Evans goes on to link this way of thinking of a day with certain cognitive dispositions that a thinker might have. The idea, I think, is clearer with "here": To think of a place as here is, in part, to be disposed to judge thoughts about 'here' as true or false on the basis of one's perceptions of where one is. One can have this disposition with respect to a given place simply by being there; in particular, one does not need to be able to identify it by description.
We'll not discuss section IV. It is on 'cognitive dynamics', and is interesting, but there is too much in this paper for us to discuss everything.
In section V, Evans turns his attention briefly to "I"-thoughts. There are two main topics of discussion. The first (pp. 312-4) is whether the idea of "unshareable" thoughts is so unFregean as to be completely unavailable to Frege. Evans denies that it is.
Evans's main argument here consists in (i) distinguishing shareability from objectivity; (ii) claiming that it is the latter that really matters to Frege, since objectivity is what distinguishes senses from ideas; and (iii) insisting that unshareable thoughts can still be objective. How successful is this argument? What does the objectivity of an unshareable thought consist in?
The second topic concerns the extension of this idea to "now" and "here". As Perry had noted, Frege will need a "primitive" way in which one might think of each time and each place, which Perry derides as "very implausible". Evans responds that there is nothing at all implausible about the idea that certain ways of thinking of objects should only be available if one stands in certain spatial, temporal, or causal relations to those objects (e.g., perceives them).
Evans does not actually talk much about demonstratives (as opposed to indexicals) in this paper—he develops views about this topic in his book Varieties of Reference—but in a way they are the most natural case for his view. The idea would be that, at least for so-called "perceptual" demonstratives, the way of thinking that is associated with them involves connecting that particular thought with certain information one is receiving perceptually. Can you see how this might allow Evans to deal with the Enterprise case?
In section VI, Evans argues that Perry's view is, at best, a "notational variant" of Frege's. Evans uses his own notation to make this point. Let me try to explain it.
(12) <Sense on d of 'today', Sense of '(ξ) is F'>
(13) <λx(R2(x,d)), Sense of '(ξ) is F'>
(14) <d, λxλy(R2(x,y)), Sense of '(ξ) is F'>
(12) is supposed to be a relatively 'standard' way in which one might think of the sense of an utterance, on day d, of "Today is F": It's the pair of the sense "today" has on day d and the sense of the predicate. (13) elaborates this in terms of Evans's idea of senses as "accounts": R2(x,d) is supposed to be the relation in which someone, x, must stand to day d in order to be thinking of d as 'today'; the 'lambda-abstract' λx(R2(x,d)) means: the property of standing in the relation R2 to d. So Evans is thinking of the sense of 'today' on d as the property in which one must stand to d in order to be thinking of d as 'today'. (14) then pulls the first part of (13) apart into two pieces: the day d and the relation λxλy(R2(x,y)) in which one must stand to it to be thinking of it as 'today'.
With this in place, Evans's criticism of Perry is that, when he speaks of entertaining a P-thought 'in a particular way', his view is just a notational variant of Frege's. Why so?