Abstract
The first step in responding to the challenge of external world skepticism is to get clear on the structure of the skeptic’s argument. The most prominent varieties of skeptical arguments either rely on closure principles or underdetermination principles. The relationship between these two sorts of arguments is contentious. Some argue that these arguments can independently motivate skepticism. Others argue that they are really equivalent. I argue that although these two arguments are distinct, their independence is not as obvious as some have thought. The fact that these arguments are not equivalent is important because skeptical arguments that appeal to underdetermination principles cannot be refuted by simply denying closure. So, the strategy for responding to skepticism offered by Nozick/Dretske does not seem an adequate solution.
Similar content being viewed by others
Notes
Cohen (1998) makes this claim; however, he argues that the two arguments are related. Huemer (2000) seems to think this as well because he claims that the skeptical problem raised by the brain-in-a-vat scenario is best understood as an issue of underdetermination, instead of an argument that appeals to closure. Vogel (1990b, 1993, 2004, 2005) also seems to think of the two arguments as separate, though he claims that external world skepticism is an underdetermination problem.
By “propositional justification” I mean the sort of justification that S has for p when she has good reasons for believing p, whether or not she actually believes p. Additionally, I will be assuming that in order for S to have propositional justification that p her reasons simply have to support p to a higher degree than they do ~p.
The formulation of this argument is adapted from Cohen’s (1998) formulation. The most noticeable difference between his formulation and mine is that I have replaced ‘I know p’ in his formulation with ‘p is propositionally justified for me’.
This formulation is essentially Cohen’s (1998) slightly modified formulation of Brueckner’s (1994) formulation. I have modified Cohen’s formulation by replacing ‘justifies’ with ‘propositionally justifies’. The phrase ‘propositionally justifies’ in this formulation should be understood as saying that S’s evidence on balance supports the proposition in question.
The recent literature on closure principles makes clear that there are many difficulties in trying to produce a problem-free formulation of a correct closure principle. However, these difficulties can be set aside because they will not be directly relevant to the current endeavor.
For this principle and the other epistemic principles throughout this paper ‘S’s evidence’ should be understood to refer to S’s total evidence.
For one’s evidence to favor p over q is simply for one’s evidence to support p to a higher degree than it does q.
Again, I follow Cohen (1998) in formulating this argument, but again I change the formulation so that it is in terms of propositional justification instead of simply justification and knowledge.
This formulation is essentially Brueckner’s (1994). Throughout my discussion of these issues, I will replace instances of ‘justifies’ in Brueckner’s and Cohen’s formulations with ‘propositionally justifies’.
Brueckner (1994).
Cohen (1998).
Cohen (1998, p. 158) , footnote 30. Below I will argue that there are good reasons to not accept INC, and that it is not very hard to see why one might fail to accept it.
Ibid. p. 158. I have modified this principle slightly by replacing ‘justifies’ and ‘justify’ with ‘propositionally justifies’ and ‘propositionally justify’, respectively.
Feldman (2004) expresses sympathy for this sort of conception of evidence.
Cases of this sort against INC are easily multiplied. All that one needs to generate this sort of case is for S to have good independent reasons for believing two inconsistent propositions and for S to be unaware of the inconsistency of the propositions.
One might worry that the falsity of INC implies the falsity of what Feldman (2007) calls the “Uniqueness Thesis”, which is the claim that given a particular body of evidence there is a unique doxastic attitude that it is rational to have toward any proposition. However, the considerations raised against INC do not entail a particular position with respect to the Uniqueness Thesis. Denying INC commits one to claiming that it is possible to be justified in believing inconsistent propositions, however, it does not commit one to believing that it is possible (or impossible) to be justified in believing a proposition and justified in disbelieving that same proposition given a single body of evidence. So, one can deny INC without being committed to denying (or accepting) the Uniqueness Thesis. For further discussion of the Uniqueness thesis see Brueckner and Bundy (2011), Kelly (2010) and White (2005).
Pritchard (2005, p. 41) I have slightly modified this formulation. I have replaced ‘justified’ in the original formulation with ‘propositionally justified’.
Ibid. p. 39. I have slightly modified this formulation. Where this formulation says ‘propositionally justify p for S’ the original formulation says ‘justify S in believing p’.
It is worth noting that these principles do not support the premises in the above formulations of Closure and Underdetermination. The reason for this is that both CJ* and UP* require S to know that the two propositions are inconsistent, but the relevant premises in Closure and Underdetermination (C1 and U1) do not. This is not a major concern because both arguments can be reformulated so that CJ* and UP* do support the relevant premises. Having noted the disconnect between CJ* and UP* and Closure and Underdetermination, respectively, I will set this issue aside for the remainder of this paper because nothing that follows hangs on it.
See David and Warfield (2008) for a discussion of the difficulty of properly formulating closure principles.
Although CJ* and UP* are not exactly the same formulations that Brueckner uses in his argument, it is doubtful that he would object to Pritchard’s use of them in responding to his argument. Especially, given the difficulties for CJ and UP discussed above.
Pritchard (2005, pp. 41–42 ) (A) is an instance of CJ* and (B) is an instance of UP*.
Pritchard (2005, p. 42) I have added the premise 3a′ to make the final steps in the argument more explicit.
Ibid. p. 43.
Ibid. p. 43.
Admittedly, there are different formulations of these theories and one might be inclined to think that there is a super-theory that can reconcile the two theories. However, for present purposes I will assume that this is not the case. That is, I assume that there is one formulation of each theory, we have strong evidence supporting the theory, we have no evidence that there is a super-theory that we may discover, and that we know the two theories are inconsistent.
Thanks to Earl Conee for pointing out this possibility concerning sentences in Liar’s Paradox situations.
Jonathan Vogel has suggested to me that it might be possible to show that CJ* and UP* are equivalent without relying on INC* by making some assumptions about how probability theory is applicable to propositional justification. If this is correct, the case for claiming that Closure and Underdetermination are distinct arguments might be even more tenuous than I have suggested.
References
Brueckner, A. (1994). The structure of the skeptical argument. Philosophy and Phenomenological Research, 54, 827–835.
Brueckner, A., & Bundy A. 2011. On “epistemic permissiveness”. Synthese. doi:10.1007/s11229-011-9921-9.
Byrne, A. (2004). How hard are the sceptical paradoxes? Nous, 38, 299–325.
Cohen, S. (1998). Two kinds of skeptical argument. Philosophy and Phenomenological Research, 58, 143–159.
David, M., & Warfield, T. A. (2008). Knowledge—Closure and skepticism. In Q. Smith (Ed.), Epistemology: New essays (pp. 137–187). Oxford: Oxford University Press.
Dretske, F. (1970). Epistemic operators. Journal of Philosophy, 67, 1007–1023.
Dretske, F. (2005a). The case against closure. In M. Steup & E. Sosa (Eds.), Contemporary debates in epistemology (pp. 13–26). Malden, MA: Blackwell Publishing.
Dretske, F. (2005b). Reply to hawthorne. In M. Steup & E. Sosa (Eds.), Contemporary debates in epistemology (pp. 43–46). Malden, MA: Blackwell Publishing.
Feldman, R. (1995). In defense of closure. Philosophical Quarterly, 45, 487–494.
Feldman, R. (2004). “The ethics of belief” in Evidentialism (pp. 166–195). New York: Oxford University Press.
Feldman, R. (2007). Reasonable religious disagreements. In L. Antony (Ed.), Philosophers without gods: Meditations on atheism and the secular life (pp. 194–214). Oxford: Oxford University Press.
Feldman, R., & Conee, E. (2004). “Making sense of skepticism” in Evidentialism (pp. 277–306). New York: Oxford University Press.
Greco, J. (2000). Putting skeptics in their place. Cambridge: Cambridge University Press.
Greco, J. (2008). Skepticism about the external world. In J. Greco (Ed.), The oxford handbook of skepticism (pp. 108–128). Oxford: Oxford University Press.
Hawthorne, J. (2005). The case for closure. In M. Steup & E. Sosa (Eds.), Contemporary debates in epistemology (pp. 26–42). Malden, MA: Blackwell Publishing.
Huemer, M. (2000). Direct realism and the brain-in-a-vat argument. Philosophy and Phenomenological Research, 61, 397–413.
Kelly, T. (2010). Peer disagreement and higher-order evidence. In R. Feldman & T. A. Warfield (Eds.), Disagreement (pp. 111–174). Oxford: Oxford University Press.
Nozick, R. (1981). Philosophical explanations. Cambridge, MA: Harvard University Press.
Pritchard, D. (2005). The structure of sceptical arguments. Philosophical Quarterly, 55, 37–52.
Vogel, J. (1990a). Are there counterexamples to the closure principle? In M. Roth & G. Ross (Eds.), Doubting: Contemporary perspectives on skepticism (pp. 13–27). Dordrecht: Kluwer Academic Publishers.
Vogel, J. (1990b). Cartesian skepticism and inference to the best explanation. Journal of Philosophy, 87, 658–666.
Vogel, J. (1993). Dismissing skeptical possibilities. Philosophical Studies, 70, 235–250.
Vogel, J. (2004). Skeptical arguments. Philosophical Issues, 14, 426–455.
Vogel, J. (2005). The refutation of skepticism. In M. Steup & E. Sosa (Eds.), Contemporary debates in epistemology (pp. 72–84). Malden, MA: Blackwell Publishing.
White, R. (2005). Epistemic permissiveness. Philosophical Perspectives, 19, 445–459.
Yalcin, U. D. (1992). Skeptical arguments from underdetermination. Philosophical Studies, 68, 106–122.
Acknowledgments
I am grateful to Earl Conee, Rich Feldman, Andrew Moon, Jonathan Vogel, Brad Weslake and an anonymous reviewer for helpful comments on earlier drafts.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
McCain, K. Two skeptical arguments or only one?. Philos Stud 164, 289–300 (2013). https://doi.org/10.1007/s11098-012-9858-y
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11098-012-9858-y