Brains, Persons, and Society *** ABSTRACTS    Cervelli, Persone e Società ***ABSTRACTS

Two-Dimensionalism and the Contingent A Priori

In an influential article in the seventies, Donnellan (1979) argued that what can be properly counted as knowable a priori in examples of the contingent a priori like those involving 'one meter' or 'Neptune' famously proposed by Kripke is not the very same singular content that is contingent; he distinguished for that between knowing a true proposition expressed by an utterance, and knowing that an utterance expresses a true proposition. Evans (1979) replied that, at least for a very specific sort of cases involving “descriptive names”, a related proto-two-dimensionalist solution should be preferred, on which it is not the singular contingent content, but rather a general descriptive one which is knowable a priori. In a series of papers, Robin Jeshion (2000, 2001) has recently attacked Donnellan's proposal, arguing in favour of the most straightforward interpretation of Kripke's claim: in the relevant cases, the very same singular content can be both contingent and knowable a priori. In my paper, I will argue that this cannot be the case; I will appeal to a generalized version of two-dimensional semantics to advance an account of the Kripkean cases along the lines of Evans's, and I will argue that Jeshion's compelling arguments against Donnellan's view do not apply to this version.

The main argument will be based on contrasting cases of failure of reference such as (1) with successful cases such as (2):

(1)        Vulcan causes perturbations in Mercury’s orbit, if it exists

(2)        Neptune causes perturbations in Uranus’s orbit, if it exists

Someone who, like Jeshion, wants to defend that it is the very singular proposition expressed on Millian assumptions by (2) that is both contingent and a priori faces a problem with (1). On the 2-D take on Donnellan’s view, that singular, object-dependent content can be known a priori only because that is understood only by accessing a general descriptive “diagonal” content. On this view, (1) does not pose any special problem: there still is still a truth to be known a priori. The defender of the alternative view confronts a dilemma, relative to which of the two available options she chooses: either it is a priori knowledge of the content of that utterance wthat is claimed, or it is merely a priori defeasible justification.

If the second option is chosen, that it is merely a priori defeasible justification that competent speakers have concerning the truth of (1), then she can argue that, although acceptance of (1) was justified a priori, empirical findings have shown that it is not true. The problem with this is that, although there are clear examples of the empirical defeasibility of a priori beliefs (see Jeshion 2002), it is defeasibility by, say, the testimony of relevant experts that those examples are based on; defeasibility by straightforward empirical findings like those establishing the non-existence of Vulcan is a much more doubtful matter.

 If, on the other hand, the first option is adopted, that it is merely a priori knowledge that competent speakers have concerning the truth of (1),  the defender of the view that the singular object-dependent content of (1) is known a priori will have to envisage true but gappy propositions. This would require a semantics that is technically attainable, and in fact has been adopted recently by Sainsbury (2005). I will argue, however, that the required semantics is theoretically in need of a justification that is not at all easy to provide. Lehmann (2002) includes a useful discussion of different kinds of free logics, and the problem they confront to justify the truth-conditions they ascribe to referential sentences. Semantics for free logics should justify the non-validity of rules like, say, existential generalization, and at the same time the truth of sentences like (1), or instances of excluded middle involving non-referring terms. A bivalent proposal like Burge’s (1974) achieves this by stipulating that all atomic sentences are false; however, as Lehmann notes (op. cit., 226), Burge’s justification for the stipulation presupposes bivalence, which is at stake once we envisage non-referring terms. Non-bivalent supervaluationist semantics are among the most popular, but they confront a similar problem. Lehmann rightly criticizes a proposal by Bencivenga based on a “counterfactual theory of truth”: “Why should truth, which is ordinarily regarded as correspondence to fact, be reckoned in terms of what is contrary to fact? Why should we reckon that ‘Pegasus is Pegasus’ is true because it would be true if, contrary to fact, ‘Pegasus’ did refer?” (op. cit., 233), concluding, “If supervaluations make sense in free logic, I believe we do not yet know why” (ibid). I will argue that it is only 2-D accounts, such as the one on which I will rely, which are in a position to provide the required semantic justification for supervaluationist semantics for free-logics.
 

References

Burge, Tyler (1974): “Truth and Singular Terms,” Noûs 8, 309-25.

Donnellan, Keith (1979): “The Contingent A Priori and Rigid Designation,” in French, P., Uehling, T. and Wettstein, H. Contemporary Perspectives in the Philosophy of Language, 45-60, Minneapolis: University of Minnesota Press.

Evans, Gareth (1979): “Reference and Contingency,” The Monist 62, 161-189. Also in his Collected Papers, Oxford: Clarendon Press 1985.

Jeshion, Robin (2000): “Ways of Taking a Meter,” Philosophical Studies 99, 297-318.

Jeshion, Robin (2001): “Donnellan on Neptune,” Philosophy and Phenomenological Research 63, 111-135.

Jeshion, Robin (2002): “The Epistemological Argument Against Descriptivism,” Philosophy and Phenomenological Research 64, 325-345.

Lehmann, Scott (2002): “More free logic”, in Gabbay, ed. Handbook of Philosophical Logic, 2nd edition, Vol. 5, Kluwer-Academic Publishers 197-259.

Sainsbury, Mark (2005): Reference without Referents, Oxford: Clarendon Press.