Abstract
The notion of conceivability has traditionally been regarded as crucial to an account of modal knowledge. Despite its importance to modal epistemology, there is no received explication of conceivability. In recent discussions, some have attempted to explicate the notion in terms of epistemic possibility. There are, however, two notions of epistemic possibility, a more familiar one and a novel one. I argue that these two notions are independent of one another. Both are irrelevant to an account of modal knowledge on the predominant view of modal reality. Only the novel notion is relevant and apt on the competing view of modal reality; but this latter view is problematic in light of compelling counterexamples. Insufficient care regarding the independent notions of epistemic possibility can lead to two problems: a gross problem of conflation and a more subtle problem of obscuring a crucial fact of modal epistemology. Either problem needlessly hampers efforts to develop an adequate account of modal knowledge. I conclude that the familiar notion of epistemic possibility (and the very term ‘epistemic possibility’) should be eschewed in the context of modal epistemology.
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Notes
This qualification is dropped henceforth. It should be assumed that the intended sense of possibility is metaphysical possibility, unless explicitly noted otherwise.
The use of propositions in the text above, to characterize modal knowledge and the putative significance of conceivability to modal epistemology, should not obscure the fact that the present discussion is compatible with a very robust view of the nature of modal reality. One might regard modal reality as grounded in the natures of things or their essences (see, for example Fine 1994, Lowe 1998, Oderberg 2001); however, knowledge of such natures and essences is most perspicuously presented and discussed as propositional.
A characterization of this view, and some discussion of it, follow in § 6 below.
The view, or its underlying sentiment, seems to be somewhat ancient and widespread. However, I know of no place where it is explicitly endorsed, so it is difficult to identify its origins or canonical presentations. Although it undoubtedly has roots that extend further, into medieval discussions of metaphysics, it was prevalent throughout the middle decades of the 20th century and is certainly suggested by the work of Quine and Carnap. See, the papers included in Quine (1980, 2006); see, as well, Carnap (1988) and the papers appended to this edition of the work. The view is operative in the contemporary work of Jackson and Chalmers. See Jackson (1994, 1998) and Chalmers (1996, 2002). This last point is revisited in § 4.
One should construe the concept expressed by a term as a set of properties most or all of which are associated with the referent or extension of that term by any competent user of it.
There are many varieties of robust views of the nature of modal reality, that is, views on which modal reality is not determined by the practices of conscious beings, but rather by the natures of things (or the natures of their counterparts). See, for an indication of this variety, the papers collected in Loux (1979), among which are now-classic papers on the metaphysics of modality by Robert Adams, David Lewis, Alvin Plantinga, and Robert Stalnaker. See, also, those papers cited in Note 2 above.
This account of epistemic possibility is over-simplified. These simplifications, however, are irrelevant to the purposes of the present discussion. For thorough and sophisticated discussions of epistemic possibility see Hacking (1967, 1975); Teller (1972) and DeRose (1991). Hacking (1967) can be regarded as a locus classicus of epistemic possibility. Therein, Hacking carefully defines the notion and traces it back to G.E. Moore who, in his Commonplace Book, devotes a good deal of attention to it.
This is a classic example in the context of discussions of the nature of conceivability and the sense of this notion relevant to modal knowledge. It has been employed for different purposes. The example is first discussed by William Kneale (1949: 80) for the purpose of demonstrating that some “conceivable” propositions are necessarily false and, thus, that the conceivability of a proposition provides no evidence of its possibility. The example has been revisited, for example in Yablo (1993: 8 ff.), for the purpose of clarifying the modally relevant notion of conceivability. Yablo argues that the epistemic sense of conceivable, the sense in which both Goldbach’s conjecture and its negation are conceivable, is not the sense of conceivability relevant to modal knowledge—precisely for those reasons cited by Kneale. Consideration of Goldbach’s conjecture is also familiar from another context, namely, from Kripke (1980: 36–38), where Kripke employs the example to argue that not all necessary truths are known apriori and, hence, that one must distinguish aprioricity from (metaphysical) necessity. See Hirsch (1986: 245) for a caution not to exaggerate the relevance of Goldbach’s conjecture and other mathematical examples in this context. The example is also discussed in Worley (2003).
Note that the actual space behind the door could indeed have been bigger, in the sense that had the world been different, that is, were we in a different world, that space might have been much larger. However, the space actually behind the door could not have been bigger, given that the quantity of space with respect to a particular space is essential to it. This last claim, about one of the essential features of a given space, seems to me to be obviously true; if a given space had more or less space it would be a different space—just as if a given length (or number) were greater or lesser it would be a different length (or number).
Stephen Yablo presents (and rejects) another explication of conceivability in terms of epistemic possibility: a proposition, p, is conceivable to a subject, S, if and only if the possibility of the state of affairs represented by p is consistent with what S knows. See Yablo 1993: 20. This notion of conceivability is even weaker than the epistemic notion considered in the text. Thus, it is no more relevant to modal epistemology than that notion is.
See the references in Note 8 above.
Kripke (1980: 103–5, 141–44, 150–53). One should construe two situations as being “qualitatively identical epistemically” to a subject, if both induce perceptual states having the same phenomenal character, so that there is no sensory evidence provided by either state that could distinguish between distinct objects in the two situations that have the same appearances.
Although he does so for reasons different than those discussed in the text, Stephen Yablo distinguishes, in passing, epistemic possibility from conceptual possibility. See Yablo (2002: 442–3). Yablo is one of the few philosophers in current discussions of modal epistemology to make this distinction (see also Yablo 2000: 99ff.). However, in earlier work, Yablo (1993: 22ff.), when discussing Kripke, Yablo conflates epistemic and conceptual possibility. See Yablo’s conceivability ep, presented and discussed in Yablo (1993: § IX).
Or, alternatively, p is “epistemically possible” when p “is not ruled out a priori” (Chalmers 2002: 157).
Those who think of conceivability in this way are almost certainly not ignorant of the distinction between epistemic possibility (in the sense of § 3 above) and conceptual possibility. Chalmers seems to be aware of the distinction when, in passing, he cautions one not to confuse his preferred notion of conceivability to one on which “a statement is conceivable if for all we know it is true” (Chalmers 1996: 66). It is appropriate, then, to wonder about the motivation for ignoring the usage of the term ‘epistemic possibility’ in order to use it to express the notion of conceptual possibility (rather than, as one would expect, epistemic possibility). One explanation, the simplest, is that those who refer to conceptual possibility as “epistemic possibility” do so because the former notion is illuminated by Kripke’s discussion of qualitatively identical epistemic states.
See Segerberg (1973) for the basic idea and some discussion of its history. The philosophical interest in such operators was originally stimulated by the observations that they were of use in developing temporal logic and that they appeared to be necessary to give a proper formal analysis of the semantics of certain sentences in natural language employing tense and temporal operators. Their use was extended to modal logic, in part as a result of attempts to formalize the notion of actuality; (See Davies and Humberstone 1980) the basic idea underlying such operators has also been used to provide a formal semantic analysis of natural language. (See, for some of the most famous and influential examples of formal semantic analyses along these lines, the papers on language in Lewis (1983) and Stalnaker (1999)).
I do this is in detail elsewhere. See my “Two-dimensionalism and Modal Reality”.
Worley (2003: 17).
This is evident in Stalnaker (2002), where Stalnaker seems to come to the same conclusion after much discussion of ultimately irrelevant semantic issues.
One such explication is in terms of the imaginability of a proposition. I argue, in Fiocco (2007), that accounts of modal knowledge in terms of the conceivability qua imaginability of propositions are irredeemably problematic.
References
Balog, K. (1999). Conceivability, possibility, and the mind-body problem. Philosophical Review, 108, 497–528.
Brueckner, A. (2001). Chalmers’s conceivability argument for dualism. Analysis, 61, 187–193.
Carnap, R. (1988). Meaning and necessity, Midway Reprint. Chicago: University of Chicago Press.
Chalmers, D. (2002). Does conceivability entail possibility? In T. Gendler & J. Hawthorne (Eds.), Conceivability and possibility. Oxford: Oxford University Press.
Chalmers D. (1996). The conscious mind. New York: Oxford University Press.
Davies, M., & Humberstone, L. (1980). Two notions of necessity. Philosophical Studies, 38, 1–30.
DeRose, K. (1991). Epistemic possibilities. Philosophical Review, 100, 581–605.
Fine, K. (1994). Essence and modality. Philosophical Perspectives, 8, 1–16.
Fiocco, M. O. (2007). Conceivability, imagination and modal knowledge. Philosophy and Phenomenological Research, 74, 364–380
Gendler, T., & Hawthorne, J. (Eds.) (2002). Conceivability and possibility. Oxford: Oxford University Press.
Hacking, I. (1975). All kinds of possibility. Philosophical Review, 84, 321–337.
Hacking, I. (1967). Possibility. Philosophical Review, 76, 143–168.
Hirsch, E. (1986). Metaphysical necessity and conceptual truth. Midwest Studies in Philosophy, XI, 243–256.
Jackson, F. (1998). From metaphysics to ethics: A defense of conceptual analysis. Oxford: Oxford University Press.
Jackson, F. (1994). Armchair metaphysics. In M. Michael & J. O’Leary-Hawthorne (Eds.), Philosophy in mind. Dordrecht: Kluwer.
Kneale, W. (1949). Probability and induction. Oxford: Clarendon Press.
Kripke, S. (1980). Naming and necessity. Cambridge, MA: Harvard University Press.
Lewis, D. (1983). Philosophical papers (Vol. I). New York: Oxford University Press.
Loux, M. (Ed.) (1979). The possible and the actual: Readings in the metaphysics of modality. Ithaca: Cornell University Press.
Lowe, E. J. (1998). The possibility of metaphysics: Substance, identity and time. Oxford: Clarendon Press.
Michael, M., & O’Leary-Hawthorne, J. (Eds.) (1994). Philosophy in mind. Dordrecht: Kluwer.
Oderberg, D. (2001). How to win essence back from essentialists. Philosophical Writings, 18, 27–45.
Quine, W. V. (2006). The ways of paradox and other essays (revised edition). Cambridge, MA: Harvard University Press.
Quine, W. V. (1980). From a logical point of view (3rd ed.). Cambridge, MA: Harvard University Press.
Segerberg, K. (1973). Two-dimensional modal logic. Journal of Philosophical Logic, 2, 77–96.
Soames, S. (2004). Reference and description. Princeton, NJ: Princeton University Press.
Stalnaker, R. (2002). What is it like to be a zombie? in T. Gendler & J. Hawthorne (Eds.), Conceivability and possibility. Oxford: Oxford University Press.
Stalnaker, R. (1999). Context and content: Essays on intentionality in speech and thought. Oxford: Oxford University Press.
Teller, P. (1972). Epistemic possibility. Philosophia, 2, 303–330.
Tidman, P. (1994). Conceivability as a test for possibility. American Philosophical Quarterly, 31, 297–309.
van Cleve, J. (1983). Conceivability and the Cartesian argument for dualism. Pacific Philosophical Quarterly, 64, 35–45.
Worley, S. (2003). Conceivability, possibility and physicalism. Analysis, 63, 15–23.
Yablo, S. (2002). Coulda, Woulda, Shoulda. In T. Gendler & J. Hawthorne (Eds.), Conceivability and possibility. Oxford: Oxford University Press.
Yablo, S. (2000). Textbook Kripkeanism and the open texture of concepts. Pacific Philosophical Quarterly, 81, 98–122.
Yablo, S. (1993). Is conceivability a guide to possibility? Philosophy and Phenomenological Research, 53, 1–42.
Acknowledgements
I would like to express my deep gratitude to Anthony Brueckner, Jonathan Dancy, Matthew Hanser and Nathan Salmon for very helpful comments on previous drafts of this paper, as well as to the two anonymous referees for Erkenntnis whose insightful comments enabled many improvements to the final version.
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Fiocco, M.O. Conceivability and Epistemic Possibility. Erkenn 67, 387–399 (2007). https://doi.org/10.1007/s10670-007-9057-y
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DOI: https://doi.org/10.1007/s10670-007-9057-y