Volume Two: Symposia and Invited Papers || A Reply to Brian Loar's "Must Beliefs Be Sentences?"

A Reply to Brian Loar's "Must Beliefs Be Sentences?"Author(s): Jerry FodorSource: PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association,Vol. 1982, Volume Two: Symposia and Invited Papers (1982), pp. 644-653Published by: The University of Chicago Press on behalf of the Philosophy of Science AssociationStable URL: http://www.jstor.org/stable/192449 .

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A Reply to Brian Loar's "Must Beliefs Be Sentences?"

Jerry Fodor

Massachusetts Institute of Technology

In the parts of his paper that I'll be concerned with here, Brian Loar contrasts two accounts of the nature of beliefs. According to the first, beliefs (and, mutatis mutandis, other propositional attitudes) are mental states that are individuated by reference to their functional role (a functional role, in turn, is a pattern of causal relations that a mental state bears to an organism's proximal inputs and outputs and to its other mental states). According to the second account, a belief is a relational state of which the relata are, on the one hand, the organism which entertains the beliefs, and on the other a mental representation. We needn't, for present purposes, worry much about what sorts of things mental representations are; for orientation, think of mental particulars which serve something like the function that was assigned to "Ideas" in classical empiricist episte- mology. Like Ideas, mental representations are supposed to be pos- sessed simultaneously of causal and semantic properties; mental representations are therefore species of symbols. However, mental representations are unlike Ideas in that they are usually taken to be structured in some way analogous to the structure of natural language sentences. Mental representations, that is to say, are supposed to be species of discursive rather than iconic symbols. It is because of this latter feature of mental representation theory that the metaphor of a language of thought seems apposite.

Loar apparently takes it that the functional role account of beliefs and the mental representation account of beliefs are, as it were, friendly competitors. For though the two theories clearly have a lot in common, and though Loar acknowledges that it could turn out that both are true, still he is inclined to believe that the arguments favoring the functior,al role story are in better shape than those that favor mental representations. Indeed, Loar presents a number of considerations that are supposed to militate for the former as against the latter. By contrast, my view (and the burden of my argument in this commentary) is this: the two accounts are, to all intents and

PSA 1982, V1 lume 2, pp. 644-653 Copyright C 1983 by the Philosophy of Science Association



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purposes, inseparable. On the one hand, the mental representation approach implicitly commits one to individuating mental states by their functional roles; and, on the other, it's only by endorsing the mental representation view that we can make clear how a functional role theory of propositional attitudes could be true.

Well, to get to details, Loar's picture seems to be as follows: somebody who is into mental representations could, at his discretion, also embrace a functional role account of the individuation of beliefs. After all, mental representations are supposed to have causal properties, so reference to mental representations might come into a theory by way of answering the question: 'what precisely is it that has the functional role that, according to functional role theorists, provides the individuation condition for the belief that P?' Answer: it is a certain relational state; viz., the very relational state whose relata are the believing organism and an appropriate mental symbol (see above). But, though Loar sees that a mental representation theorist could accept the view that there is some functionally individuated mental state that all and only P- believers share (some mental state with an "interpersonally ascribable" functional role, as Loar puts it), still he holds that this would be an excresence on-the mental representation theory.

What I take it that Loar has in mind here is that even if the mental representation theorist has the option of individuating beliefs by their functional roles, still he also has another option; viz., that of individuating beliefs by reference to the character of the mental synbols that the organism is allegedly related to when it has the beliefs. Suppose (per impossible) that we think in English, so that believing that it's going to rain is bearing a certain specified relation (call it R*) to the English sentence "it's going to rain". Then we can say what it is to have the belief that it's going to rain without specifying the functional role of that belief. In fact, we just did: it's to bear R* to "it's going to rain".

So that's the sense in which Loar thinks that the functional role story is "stronger" than the mental representation story: according to the former, but not the latter, belief-that-it's-going-to-rain ascriptions imply that there is an interpersonally shared functional role that all and only beliefs-that-it's-going-to-rain have in common.

I think, however, that this way of viewing the situation is misleading. For in order to divorce the individuation conditions for beliefs from the satisfaction of some interpersonally ascribable functional role, the mental representation theorist would need to have a NONFUNCTIONAL criterion for the type-token relation for mental representations. And we have not got such a criterion and, in my view, it is most unlikely that we are going to get one.

Here is the point in a nutshell. Suppose that tokens of the belief that it's raining are to be identified with tokenings of the formula F while tokens of the belief that it's snowing are to be identified



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with tokenings of the formula G. Then, presumably, we can distinguish between the beliefs if we can distinguish between the corres- ponding tokens; in principle, the type/token relation for mental symbols provides a criterion for the individuation of beliefs if the mental representation account of beliefs is true. But now, how is the type-token distinction for mental symbols to be drawn? Not, presumably, orthographically or acoustically as in the case of written/ spoken tokenings of English sentences. Even if we think in English, token thoughts are surely not sequences of graphemes or phones. So, then, presumably some other way. If you accept type physicalism, you may suppose that mental representations of the same (as it were) linguistic type are ipso facto physical events of the same neural type. But few mental representation theorists accept type physicalism; and, even those who do presumably don't want the theory of belief to entail it.

This means, so far as I can see, that the only option is to assume that the type/token relation for mental representations is itself functionally specified. What makes something a token of the mental symbol "it's raining" is the causal properties of the symbol rather than its shape, charge or biochemical peculiarities. But if that is true then, in practice at least, the mental representation theorist is committed to much the same claims about interpersonal functional roles as his erstwhile antagonist. So far, mental representation theorists and functional role theorists look as if they sink or swim together.

Nevertheless, I agree with Loar that the mental representation story is in some sense the more adventurous of the two. In principle, we could identify beliefs with states that have characteristic functional roles without going on to try and say, as mental representation theorists do, what the (as it were) internal composition of such states may be. But I think, for two reasons, that that would be a bad idea. First, what is so good about not being adventurous? It is hardly that the excitement of philosophical speculation, however ven- turesome, is likely to strain even a delicate nervous sensibility; and there is the Popperian point that confirming a strong hypothesis is ipso facto more illuminating than confirming a weak one. Second, not asking a question is not a way of answering it, and, sooner or later, the functional role theorist is going to have to say something about what kind of states could have the functional roles that he takes to be appropriate to the individuation of beliefs. If, in particular, no states could have the right causal properties, then the functional role theorist is in the soup. My point is that, as things stand, the relations-to-discursive-symbols story is the only plausible one about what the structure of such functional states could be.

Let me give just one reason why I think that this is so. Loar offers, as one of the prima facie arguments for mental representations, the following consideFation. "Beliefs have common structures and structured relations to each other, for example, the relation between the belief that q & p and the belief that p, which are essen- tial to their role in psychological explanation. That structure is



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language-like; hence, the argument goes, if it is realized there is a language of thought." (p. 635). However, Loar replies, we need not infer from the existence of (as it were) logical form in beliefs to the existence of mental symbols. Rather, what all conjunctive beliefs (for example) have in common might just be "...their conceptual relations to other appropriately indexed beliefs, and not (necessarily) their first-order structure." (p. 636).

Now, for starters, I do not think that "conceptual" relations to other beliefs can be what Loar actually intends. For one thing, the notion of conceptual relation is unreconstructed in his theory so it is not one to which Loar is, strictly speaking, entitled. And, for another thing, I suppose the conceptual relations of a conjunctive belief would be identical to those of any logically equivalent non- conjunctive belief; whereas, presumably, one wants a theory of propositional attitude to distinguish between, say, the belief that P & Q and the belief that ((P & -P) V (P & Q)).

What Loar's theory does have to offer - and what I presume Loar has in mind - must be that conjunctive (etc.) beliefs have their conjunctive structure in virtue of their causal/functional relation to other functionally individuated mental states. But that reply, though it is one Loar is in a position to make, really misses the point of the problem.

The point of the problem is this: complex beliefs are complex in a way that cries out for some explication of their structure in terms of constituency relations. It looks, to put it as crudely as possible, as though the belief that P & Q ought to have something P-ish and something Q-ish as its constituents; and the question is what on earth these P-ish and Q-ish things might be:

- not the propositions P and Q since, on the sort of "naturalistic" theory that Loar and I both have in mind, reference to propositions must be eliminable in the long run.

- not the belief that P and the belief that Q because the analogous solution will not work for the constituents of the belief that P v Q. That is, since you can have the belief that P v Q and not have either the belief that P or the belief that Q, it cannot be that the latter beliefs are constituents of the former.

- for similar reasons, it seems that you cannot construe the constituents of a belief as constituents of its functional role. Suppose that there is a functional role C the possession of which is what in- dividuates the belief that P v Q. It cannot be (or, at least, it cannot be in any way that I can make out) that C has as its constituents the functional roles associated (respectively) with the belief that P and the belief that Q. After all, functional roles are just causal powers, and it's not, to put it mildly, obvious that there need be anything that having the belief that P v Q causes one to think or do that is identifiably like what having the belief that P or the belief



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that Q causes one to think or do. And, even if there is some such identifiable causal role constituent in the case of relatively simple disjunctive beliefs, think of all the other (all the infinitely many other) beliefs that also have P-ish and Q-ish constituents. Does one really want to undertake the burden of showing that the causal role of, say, the belief that (if P then Q (then if P then Q or R))) has the causal roles of P, Q, and R as its constituents? I, for one, would not know where to begin.

Whereas, it is one of the lovely things about the language of thought story that it gives you the constituent relation you want for free. Specifically, it is just a condition upon the construction of a type/token relation for mental representations that tokenings of the mental symbol that serves as the object (as it were) of the belief that P v Q should (literally) contain tokenings of whatever mental symbol serves as the object of the belief that P and of whatever mental symbol serves as the object of the belief that Q. Just as token inscriptions of the formula "P v Q" contain as literal parts token inscriptions of the formula "P" and of the formula "Q".

Digression: you might suppose that the mental-representation-as- constituent story actually entails the causal-role-as-constituent story, and thereby inherits the disadvantages of the latter. For, you might argue, if tokens of the mental formulas for P and for Q are actually parts of the mental formula for P v Q, and if the causal role of a mental state is sensitive to the constituency of the formula that is tokened when one is in that state (as, indeed, it must be if what one contemplates is some form of computational psychology) then is it notgoing to turn out that the causal role of P v Q has the causal role of Q as a constituent precisely because the mental symbol for P v Q has the mental symbol for Q as a constituent? Answer: of course not. The effects of a mental tokening of P v Q need no more contain the effects of a mental tokening of P than the effects of reading that, say, if it snows in August then there will be a heat wave in December need include the effects of reading that it will snow in August. In fact, just as it is preeminently a virtue of mental representation psychology that it permits us to co-opt the linguistic notion of constituency for our account of the structure of mental states, so it is preeminently a virtue of mental representation theory that it allows us to co-opt logic and computer theory for our account of the nature of mental processes. After all, logic shows us exactly how to use the syntactic constituency of the formula "P v Q" to determine the entailments of the proposition that that formula expresses. And computer theory shows us how to build symbol handling mechanisms whose causal processes respect, in appropriate ways, the inferential relations implicit in the syntactic constituency of linguistic formulas. Once again: psychology gets all this theory for free if it once buys the mental representation story.

So what I claim is this: we need a theory of mental states (like beliefs) and of mental processes (like drawing inferences). It looks as though notions of structure, and specifically of constituency, must



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be at the heart of both theories since, to put it roughly, it is in virtue of their constituency that (complex) mental states have their semantic properties and their causal roles. The linguistic notion of constituency, implicit in the postulation of mental symbols, appears to give us just what we need; it allows us to ground our account of the semantics of mental representations in logic and to ground our account of the causal properties of mental representations in computer theory. Moreover, there are literally no competing accounts. Take away the linguistic notion of constituency, and we have no idea at all of how beliefs could have their inferential liasons or their causal roles. Loar might wish to reply that only the unelaborated causal role story counts as "explication" of belief, but I am not sure what this amounts to or why one should care. Surely neither theory provides an "analysis" (as one used to say) of the "ordinary notion" (as one also used to say) of belief. Nor do I really think that hunting for analyses (in that, or maybe any other, sense) is a reasonable occupation for grown-ups. What we do want, or so it seems to me, is just a workable theory about what beliefs are. My point has been that if the mental representation story does not provide the theory, it is unlikely that any other kind of functionalism will do so either.

I will stop pretty soon, I promise. But first, let me say just a little about some of the points Loar makes towards the end of his paper about how to run a theory of the truth conditions of beliefs.

As we have seen, the natural move for a representationalist is to assume that mental symbols have a language-like constituent structure and then to use more or less familiar logical devices to explain how the semantic properties of complex mental symbols are inherited from the semantic properties of their atomic constituents. But, notori- ously, that sort of theory says nothing about how mental representations get attached to the world (how, for example, they have 'ex- ternal' truth conditions as well as 'internal' causal roles) and something does very much need to be said about that question.

There is a recent, profoundly unpublished, paper of mine which sets out what Loar calls an "ideal indication theory". This is a long, complicated business, but the basic idea is that the truth condition of a mental representation is that state of affairs which would cause a tokening of the mental representation under ideal conditions of transparency of evidence.

I think I like this idea largely because it seems so very implaus- ible. For example, as Loar points out, and as I emphasize in my paper, it entails that any organism that has beliefs at all is omni- scient under appropriate idealization. In fact, to put the point more strongly, the whole idea is built on the insight that omniscience is, as you might say, the theoretically perspicuous condition for an account of the semantics of mental representations. Consider God. There is no problem about what makes a certain state of affairs the truth condition of one of His mental representations. Since God believes all and only the truths, His mental representations get



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tokened when, and only when, their truth conditions are satisfied. The truth conditionsof His mental representations can thus be identified with whatever states of affairs are causally necessary and sufficient for their tokenings.

This may sound pretty silly in its short version (actually, it sounds pretty silly in its long version, too). But I find it sort of grows on you after a while; at a minimum I think I can show that you have to accept it if you are going to apply to the case of mental representation the sort of "informational" semantics that philosophers like Stampe and Dretske have recently been fruitfully exploring. I won't, however, try to convince you of this here. Suffice it to say that I do not think that the sorts of objections Loar raises for the program are anywhere near decisive.

First, Loar says, "The ideal indication theory requires that every inner sentence.. .is individually sensitive to its truth condition... But this apparently conflicts with a rather basic idea about truth- conditions, namely, that the truth-condition of a new sentence is de- rivative from the independently constituted semantic properties of its constituents." (p. 638). But this is just wrong if it is supposed to suggest that the fact that, for example, the mental symbol "P & Q" has the truth conditions that it does is somehow independent of the fact that the mental symbol "P" has the truth condition that it does. On the contrary, as we have just seen, mental representation theory appeals to interformulaic relations among mental representations precisely as the vehicle for projecting the semantics of indefinitely many complex beliefs from the semantics of a presumably finite primi- tive basis. The best way to look at this is to think of the cognitive (i.e., belief-fixing) mechanisms of an organism as a physical real- ization of a function from states of affairs onto mental representations. Under appropriate idealization, the range and domain of this function are both infinite. In effect, the system has an infinity of dispositional properties of the form: token the mental representation r iff the state of affairs s obtains. The computational structure of this system is of precisely the sort familiar from truth definitions for formal languages. So that, for example, the fact that the device tokens "P & Q" iff it is the case that P and the case that Q is con- nected, in a straightforward way, with the fact that the device tokens "P" iff it is the case that P and tokens "Q" iff it is the case that Q. Under the operative idealization, and given the rules for "&", the causal conditions for tokening "P & Q" are satisfied by, and only by, the satisfaction of the causal conditions for tokening "P" and the satisfaction of the causal conditions for tokening "Q". Nothing could be further from the idea that "every inner sentence is individually sensitive" to its truth condition; and, in fact, I do not see how to make sense of that idea for any cognitive system of which the repre- sentational capacities are infinite (as they surely are for us and, I suppose, for any device with a remotely interesting mental life).

Loar's second objection is that "some theories that we accept emerged as hypotheses from the idiosyncratic abilities.. .of creative



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individuals. That there is a method that is the natural endowment of each of us, and that could have generated those hypotheses, is an interesting but far from obvious thesis." (p.638). But this objection is misled; the ideal indication theory is, in a certain attenuated sense, verificationist; but it is not - or anyhow it need not be - operationist. It has to assume, that is to say, that every cognizing organism tends toward omniscience in the limit; that the probability that one believes that P becomes arbitrarily close to unity as the evidence that P becomes arbitrarily transparent. But this does not entail that there must be anything like a method or procedure for determining whether it is the case that P since there is, in general, no method or procedure for bringing it about that evidence becomes arbitrarily transparent.

Finally, it seems to me false that the ideal indicator theory is incompatible with realism; or at least, if it is, the brain-in-a-vat considerations do not seem to me to show that it is. What the theory requires, once again, is omniscience in the evidential limit; in effect, that if we are brains in a vat, then the probability that we will come to believe that we are will increase arbitrarily as the evidence that we are brains in a vat gets arbitrarily better. But, of course, if the brain in a vat story is actually true of us now, then the evidential condition is egregiously not satisfied. Things look to us very much as though we are not brains in a vat but rather creatures in a world. I take it that nobody denies that that is the state of the evidence we have, even if one accepts the logical possibility that the evidence we have is systematically misleading.

So now let us look at Loar's argument. Supposing that I am a brain in a vat, there is, Loar says, "no doubt...a possible truth- theoretic interpretation of my beliefs which makes them about my sense-data and renders them largely true on that interpretation." (p. 640). Let us call that interpretation I. Then Brian's point is that since the ideal indicator theory requires us to accept the interpretation of our mental states that maximizes their truth over-all, then I must be the right interpretation of my current beliefs. But this is supposed to show that the ideal indicator theory must be wrong since, surely, if I am a brain in a vat, then almost everything I now believe is false.

It should now be evident what's wrong with this; simply that the idea indication theory does not require that the riqht interpretation for my beliefs is the one-1whTc`icmaximizes truth here and now. What it does require is that you maximize truth in the evidential limit. And the satisfaction of this latter requirement is entirely compatible with rejecting I as the interpretation scheme for my beliefs even though I is the interpretation scheme which would maximize truth if my evidential situation were as benighted as that of a brain in a vat. To repeat: the ideal indicator theory does not say 'pick the interpretation scheme that maximizes truth come what may'; what it says is only 'pick the interpretation scheme which maximizes truth in circumstances where the truth is what the organism has every reason to



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believe'. In my view, their failure to observe this distinction has been a serious defect in previous formulations of "principles of charity".

As for the more general issues about the relations between realism and the ideal indicator theory, they require a lot more sorting out than I have room for here. But roughly, if what realism requires is that we understand truth nonepistemically, as correspondence with states of affairs, then the ideal indicator theory is thoroughly real- istic. The epistemic considerations come in, not in saying what truth is, but only in deciding which state of affairs a mental symbol corre- sponds to if it is true; viz., that state of affairs which would cause the tokening of the symbol under conditions of ideal evidential transparency.

There is, for all that, plenty to worry about with ideal indicator theories. For one thing, they are a species of verificationism. As such they imply, as Brian correctly notes, that there are epistemic circumstances in which we could not fail to believe the true. And though this claim is attenuated in proportion as the circumstances are idealized, I will not blame you if even attenuated verificationism is more than you are prepared to swallow. So perhaps I had better close by emphasizing that the need for an account of how mental states get attached to their truth conditions is not proprietary to mental representation construals of propositional attitudes. Let beliefs and desires be construed as functional states. So long as 'causal roles' are relations to proximal events like sensory inputs and motor outputs, the question must be faced as to what relates propositional attitudes to distal events including, notably, the satisfaction of their truth conditions. Functionalism does not, I repeat, get you out of this. The problem is implicit in any due recognition that propositional attitudes have semantic properties like truth and falsity. So, to put it briefly, I would like the ideal indicator story to pan out if only because it is so whacky. But, if it does not, all of us mentalists will have to go hunting for an alternative story; and we will all have to go hunting for it together.



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Referen,es

Loar, Brian. (1983). "Must Beliefs Be Sentences?" In PSA 1i82 Volume 2. Edited by Peter D. Asquith and Thomas Nickles. East Lansing, Michigan: Philosophy of Science Association. Pages 627-643.



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Volume Two: Symposia and Invited Papers || A Reply to Brian Loar's "Must Beliefs Be Sentences?"