INTENTIONALITY AND PROBABILITY: REPLY TO YODER

AUSONIO MARRAS

In "Chisholm's Criteria of Intentionality, "1 Jesse Yoder discusses various criteria for intentional sentences: specifically, Chisholm's 1956 criteria, Chisholm's 1978 revised formulation, and my own 1982 revision of Chisholm's 1956 criteria. 2 He concurs with my assessment of the inadequacy of Chisholm's 1978 revised criterion, but finds my own revision of the 1956 criteria also inadequate. As a counterexample to my proposal, he offers the sentence:

20. It is probable that the sun will burn out in 23 billion years.

This sentence, Yoder correctly observes, is intentional by the second of Chisholm's 1956 criteria (which I accept), because neither it nor its negation implies that the subordinate clause is true or that it is false. It must be noticed, however, that according to clause (D) of my proposaly, 3 an intentional sentence is psychological (about the mental) only if it is not transformable into a non-intentional sentence. Is 20 not so transformable? It depends, first, on the general conditions one imposes on acceptable transformations, and second, on which of alternative proposed transformations of 20 one accepts as correct (if any). I argued in my 1982 paper that it is unreasonable to expect preservation of meaning, or even logicalequivalence, in all cases; often a given sentence does not have an established meaning to begin with, in which case what a transformation is e~pected to do is not to provide a meaning preserving analysis but a paraphrase (in Quine's sense) involving regimentation in the canonical language of a theory. This is just the case with sentences like 20, whose meaning is not pre- theoretically given. Thus it would not be appropriate to reject a proposed transformation of 20 just because it does not preserve its original meaning, or the set of its logical implications: 20 has no determinate meaning, or determinate set of logical implications, until we assign one to it by articulating a relevant theory. The best one can do is to correlate 20 with a theoretical statement twhose meaning, truth-

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conditions, evidential conditions, etc. are given by the theory T in which t belongs.

Yoder is doubtless correct in pointing out that 21 would not do as an "analysis" - - or, as I should say, as a "theoretical correlate" - - of 20:

21. The frequency with which suns burn out in 23 billion years is high.

This, however, shows at best that the frequency interpretation of probability is inadequate, or at least that it does not apply to probability statements concerning single or infrequent events. There are, as is well known, several alternative interpretations of probability, of which the major ones, in addition to the frequency interpretation, are the logical and the subjective? Logical theories of probability regard probability (or 'degree of confirmation') essentially as a logical relation between statements formulating evidence and statements formulating a hypothesis. This relation is expressed (roughly) as a ratio between a set of 'possible worlds' or 'state descriptions' (of. Carnap) in which a hypothesis holds together with the evidence, and the set of possible worlds or state descriptions in which the evidence alone holds. On this interpretation, 20 would be correlated with any of a number of statements which assigns a fairly high value n (0.5 < n < l ) to the ratio between the set of possible worlds in which suns burn out in 23 billion years, given the evidence, and the set of possible worlds in which the evidence alone holds. It does not seem that any such statements (whose form, roughly, is 'c = S (h & e) / S(e)' or some variant of it, where 'S(p) ' refers to the set of possible worlds in which 'p ' holds).

On the subjective interpretation of probability, 20 is properly a statement about a person's 'degree of belief' or 'confidence' in the proposit ion that the sun will burn out in 23 billion years, given certain evidence (about gases, radiation, etc.). On this interpretation, 20 is indeed intentional, but it is also psychological, and hence no eounterexample to Chisholm's thesis.

It is actually unclear whether Yoder h a s i n mind this subjective interpretation of probability when he refers to

23. It is reasonable for us to believe that there is life on Venus.

as (one of) Chisholm's interpretations of the statement that it is probable that there is life on Venus. He classifies 23 as intentional but does not regard it as an acceptable transform of the relevant probabili ty statement because "it can be reasonable to believe something to which the concept of probabili ty does not apply, as it is reasonable for me to believe that 2 + 2 = 4. Yet it is not merely probable that 2 + 2 = 4"(p. 303).

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But surely the fact that it can be reasonable to believe something to which the concept of probability does not apply, does not rule out that it can also be reasonable to believe, on the basis of empirical evidence, something to which the concept of probability does apply. Whether a proposition is certain or merely probable does not affect the question whether it is reasonable to believe it, although it may affect the question about the grounds on which the attribution of reasonableness rests. It thus remains open that probability judgments just are empirically grounded rational-belief judgments. (23 might perhaps more perspicuously be restated as "Relative to the empirical evidence, it is reasonable.., etc.".)

Yoder also objects to the rational-belief interpretation of probability on the ground that "what is reasonable for a person to believe is relative to the background of his beliefs and purposes, so it can be reasonable to believe something improbable" (p. 303). This objection, however, trades on an ambiguity between a subjectivist and an objectivist interpretation of rational belief. On the objectivist interpretation, rational-belief ascriptions are intended to apply to an ideally rational person who judges on the strength of the (publicly available) evidence alone: reference to rational belief is merely a metaphorical way of referring to a confirmation measure computable by the rules of an inductive logic, so that the objectivist rational-belief interpretation essentially reduces to the logical interpretation of probability. On the subjectivist interpretation, rational-belief ascriptions are relativized to individual persons, to their actual beliefs about the evidence and perhaps even to beliefs about expected utilities: on this interpretation, rational-belief ascriptions are evaluations of a person's confidence in ("willingness to bet on") a hypothesis, given his other beliefs and expectations. Since the degree of confidence (i.e. the subjective probability) in a hypothesis can vary from person to person, it is no embarassment on the subjective probability interpretation to suppose that it can be reasonable for someone to believe something objectively (but not subjectively) improbable. And we have seen that subjective - - probability statements are both intentional and psychological.

It has not been my intention to suggest, with these brief remarks, that any of the above interpretations of probability is adequate, or that any one is preferable to the others. I have only attempted to show that under each of these interpretations, probability statements do not provide a counterexample to Chisholm's thesis that intentionality is a mark ot the mental (cf. clause (D) in my 1982 paper). Even if none of the current interpretations of probability is adequate, it still would not follow that

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probability statements like 20 contravene Chisholm's thesis: the fact that they turn out to be intentional is inconsequential, since we can safely assume that the concept of p.robability is a non-primitive, technical concept which stands in need of analysis or theoretical explication. Hence the intentionality test is to be applied not to unexplicated probability statements like 20, but to their "paraphrases" or "transforms". If we have no adequate paraphrases, the test can't be applied. This would only show that the thesis of intentionality is an empirical (theorectical) hypothesis whose confirmation must await the results of further theoretical research. This, I think is just as it should be.5

UNIVERSITY OF WESTERN ONTARIO LONDON, ONTARIO N6A 3K7

CANADA

NOTES

Philosophia [ 7 (1987), ??? References to this paper will be gvien parenthetically in the text. See R. M. Chisholm, "Sentences about believing," in Proceedings oj" the Aristotelean Society 56 (1955-1956), 125-148, reprinted in H. Feigl et al (eds), Minnesota Studies in the Philosophy qf Science, vol. 2 (Indianapolis: University of Minnesota Press, 1958); R. M. Chisholm's reply to A. Flores, "The Thesis if lntentionality," Philosophia 7 (1978), 612-615; and Ausonio Marras, "Intentionality Revisited," Philosophia 12 (1982), 21-35. Clause (D) reads: "A sentence is psychological if and only if it is intentional and is not transformable into a non-intentional sentence" (Marras, 34) A concise survey of various interpretations of probabilitymay be found in W.C. Salmon, The Foundations of Scientific Inference (Pittsburgh: University of Pittsburgh press, 1966. It will be of interest to the reader that Chisholm has recently proposed new criteria for the psychological which make no reference to the property of intentionality. See R.M. Chisholm, "On the Nature of the Psychological," Philosophieal Studies 43 (I 983), 155-164; and "A Logical Characterization of the Psychological,"in Proceedings of the 9th International Wittgenstein Symposium, ed. R.M. Chisholm et at (vienna: Holder-pichler-Tempsky, 1985), t56-16t.

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