It was quickly realized, after "The Meaning of 'Meaning'" was published, that Putnam's point extends naturally from language to belief. (See, e.g., Colin McGinn, "Charity, Interpretation, and Belief", Journal of Philosophy, 74 (1977), pp. 521–535 (PhilPapers).) So most people who found Putnam's arguments appealing concluded that Oscar and Twin Oscar not only mean different things by the word "water" but actually have different beliefs: Oscar believes that water is wet, but Twin Oscar has no such belief; he, rather, believes that twater is wet. If so, then ordinary psychological states are not "psychological states in the narrow sense". Indeed, many concluded that there are no "psychological states in the narrow sense".
It is against this sort of view that Loar argues here. He wants to concede that Putnam has a point as far as language is concerned, but deny that the point extends to what he calls "psychological content". More precisely, he takes Putnam to have a point about what we might call "attitude ascription": the way we report or describe the mental states of other people. As a matter of linguistic usage, it would be wrong for us to say "Twin Oscar believes that water is wet". But Loar denies that we should conclude that the beliefs Twin Oscar expresses using the word "water" have a different psychological content from Oscar's. The 'that-clause' that water is wet simply does not, according to Loar, pick out what Twin Oscar actually believes.
Loar explains his notion of psychological content at the very beginning of the paper:
By psychological content I shall mean whatever individuates beliefs and other propositional attitudes in commonsense psychological explanation, so that they explanatorily interact with each other and with other factors such as perception in familiar ways. (p. 99)
The key point here is that claims about psychological content are supposed to be responsive to the needs of psychological explanation.
Loar insists, on several occasions, that his focus is on "commonsense" psychological explanation, by which he means the sort of explanation of people's actions in which we engage on an everyday basis. A similar but different thesis would focus on the sort of explanation that might be given in scientific psychology. For that sort of view, see Jerry Fodor, "Methodological Solipsism Considered as a Research Strategy in Cognitive Psychology", in his RePresentations (Cambridge MA: MIT Press, 1983), pp. 225-53) (DjVu). My own view, for what it's worth, is that Fodor's approach is preferable.
Loar sketches three sorts of arguments against particular theses about psychological content, the second being an argument due to Tyler Burge that has much the same structure as the Twin Earth case. Loar sees this argument as directed against the thesis that psychological content is determined by "conceptual or cognitive-functional roles". It does not matter for our purposes exactly what that means. (If you want to know, read section 4.2 of the SEP article on narrow content.) What matters is that this view is a form of internalism and individualism.
Loar takes these sorts of arguments to rest upon two sorts of assumptions:
- Sameness of de dicto or oblique ascription implies sameness of psychological content.
- Difference of de dicto or oblique ascription implies difference of psychological content.
Here, "de dicto" or "oblique" ascriptions are "notional" ascriptions, in Quine's sense: Ones that resist substitution of identicals.
One of the two theses (A) and (B) is implausible if the sort of ascription at issue is de re or relational. Which? In the case of the other thesis, one might actually think that Putnam's argument only needs the de re version. Why?
Loar begins his counter-argument by recounting an example due to Kripke (in "A Puzzle about Belief" (PhilPapers)). The example concerns a character Pierre who does not realize that "London" and "Londres" are the same place. It seems difficult for us to describe Pierre's beliefs: It seems right to say that he believes London is pretty, and also to say that he believes London is not pretty. But, Loar insists, it just seems obvious that Pierre has two different beliefs, because they "interact differently with other beliefs in ordinary psychological explanation". Thus, Loar thinks, the facts about Pierre's beliefs and the facts about how one might correctly report them come apart.
Loar gives one example, on p. 103, to illustrate what he means by the claim that Pierre's two beliefs "interact differently with other beliefs in ordinary psychological explanation". Give another such example. What work if any is being done by the phrase "in ordinary psychological explanation"?
Loar goes on to say that Pierre not only has two beliefs, but that "it...seems quite appropriate to regard them as distinct in content". Does he have an argument for this claim? If so, what is it? (See also p. 105.)
On pp. 102-5, Loar gives several arguments against thesis (A). Our main interest will be in (B), however, which he begins discussing at the bottom of p. 105. He focuses on a claim of Burge's that is parallel to the sort of claim for which Putnam argues using the elm–beech example. Burge has us imagine a Twin Earth on which "arthritis" means not rheumatoid inflammation of the joints but rather rheumatoid inflammation more generally, so that on Twin Earth one can truly say: Bert has arthritis in his thigh. Bert, however, knows very little about arthritis other than this his grandmother had it, that it's painful, and so forth: too little to determine for himself what it is. And of course the same is true of Bert's twin. So, like Putnam, Burge claims that, even if Bert and Twin Bert are internally identical, it is wrong to say that Twin Bert believes he has arthritis (rather than 'tharthristis') in his thigh.
Loar claims, to the contrary, that the contents of Bert's and Twin Bert's beliefs about what they each call "arthritis" are the same, "because they have the same potential for explanatory interaction with other beliefs" (p. 106). And he makes the same claim about Oscar and Twin Oscar's beliefs about water. Loar claims to find this account "intuitive", but also argues for it using two sorts of examples.
A real-life version of the first (mentioned by Gabriel Segal) concerns the word "pie". In Britain, something is only rightly called a "pie" if it has a crust on top. So, in Britain, a Key Lime Pie is not called a "pie" but rather a "tart". Suppose Bert reguarly travels between Britain and America—perhaps he lives in both, as well—and is unaware of this difference. Loar would claim here that, although the word "pie" seems to be ambiguous in Bert's mouth, he has just one belief that, say, pies are tasty.
Suppose Bert wrongly believes that the word "arthritis" is ambiguous: He thinks there are two different sorts of diseases, both called "arthritis". What would Loar have us say about Bert's beliefs in this case? How might such a case be thought to put pressure on Loar's claim that Bert and Twin Bert have the same beliefs?
The second sort of example concerns a case in which one is given a diary written by someone who is either from Earth or Twin Earth, but one does not know which. In it, we find: "I think I might have arthritis". What does Loar want to say about this case? How is that supposed to answer Burge and Putnam?
Loar considers two sorts of objections to his view:
- Oscar's belief is true in different circumstances from those in which Twin Oscar's is true. So the "narrow content" that Oscar and Twin Oscar share is not "intentional" or "representational".
- There is no sensible way to say what the common content of Oscar's and Twin Oscar's common belief is.
On pp. 107-8, Loar sketches but does not develop a response to the first objection. The locus classicus for this sort of view, which is known as a "two-factor theory", is probably Ned Block, "Advertisement for a Semantics for Psychology", Midwest Studies in Philosophy 10 (1986), pp. 615-78 (DjVu).
Loar's main response to objection (1), given on pp. 108-9, is that, even if we do not know whether "The water is cold today" was written on Earth or Twin Earth, we still know how the world would need to be for the description to be true. So there is a set of possible worlds in which it would be true, which Loar calls the realization condition for the belief. Which worlds are those worlds? (Remember that they have to be worlds that work for both Oscar and Twin Oscar.)
Loar's response to objection (2), given on pp. 109-10, is that, even if that-clauses do not specify realization conditions—which are all that are needed for ordinary psychological explanation—we have other methods by which we can express them. What are these? The obvious objection here is that ordinary psychological explanation certainly seems to proceed in terms of attributions of beliefs, etc, made using ordinary that-clauses. (Just think about how we actually explain other people's behavior.) How worrying should that objection be?