Abstract
The abductivist reply to skepticism is the view that commonsense explanations of the patterns and regularities that appear in our sensory experiences should be rationally preferred to skeptical explanations of those same patterns and regularities on the basis of explanatory considerations. In this article I critically examine Laurence BonJour’s rationalist version of the abductivist position. After explaining why BonJour’s account is more defensible than other versions of the view, I argue that the notion of probability he relies upon is deeply problematic, that he incorporates an implausible double-standard concerning a priori and a posteriori justification, and that his view is vulnerable to skepticism about the a priori. I suggest that some of these problems are due to idiosyncratic commitments BonJour makes and that abductivists would be better off without them. I conclude with some suggestions about how to improve BonJour’s abductivist response to skepticism.
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Notes
Cf. Beebe (forthcoming c) for detailed discussion of these explanatory criteria and their justification.
Other proponents of abductivism include Locke (1690/1975, bk. iv, ch. xi), Russell (1912; 1927; 1948), Broad (1925), Ayer (1956), Slote (1970), Harman (1973), Mackie (1976), Jackson (1977), Cornman (1980), Goldman (1988), Lycan (1988), Moser (1989), and Vogel (1990; 2005). Cf. Beebe (forthcoming c) for a thorough discussion of the entire family of abductivist positions.
Broad, for example, claims that some of the data to be explained by RWH include the fact that each time he looks in a certain direction he undergoes sensory experiences of roughly the same sort and that when he moves from one location to another, his sensory experiences undergo a continuous sort of change. In a discussion of Broad, Alston (1999, 227) argues, “More crucially, the patterns in experience cited as the explananda involve suppositions about the physical environment we could only know about through perception, thus introducing a circularity in the argument.”
Locke, for example, appears to beg the question when he writes, “’Tis plain, those Perceptions are produced in us by exteriour Causes affecting our Senses: Because those that want the Organs of any Sense, never can have the Ideas belonging to that Sense produced in their Minds.” Bennett (1971, 66) complains that Locke’s argument “has a premiss about sense-organs, including those of other people” but that “sense-organs are among the ‘things without us’ whose reality is in question.”
In spite of the fact that pursuing a rationalist line seems to allow abductivists a fairly obviously way to avoid begging the question against the skeptic, many abductivists have been reluctant to claim their beliefs about the virtues of various explanatory hypotheses are justified a priori. Mackie (1976, 62), for instance, recognizes that what is needed to bridge the “logical gap between ideas and reality, or between how we see things and how they are” is an explanatory hypothesis such as RWH, and he takes for granted that any such explanation will invoke nomologically necessary laws about what causes what. He also recognizes that any attempt to provide an empirical justification for belief in these causal laws will beg the question against the skeptic. However, Mackie (1976, 62) denies that causal laws can be justified a priori:
Causal laws are not merely not analytic, logical truths, they are not known or knowable a priori in any other way either. There is no method by which, from the mere inspection of an effect on its own, we can say from what sort of cause it must have arisen. So to justify an inference from an effect to a cause, we need a synthetic, a posteriori, causal law.
Thus, Mackie’s background beliefs create a dilemma for him concerning the justification of these laws: if they cannot be justified a priori, how can they be justified a posteriori without begging the question against the skeptic?
Cf. Beebe (forthcoming b) for suggestions on how someone might try to make sense of the intuitive idea that there are more positive integers than positive even integers.
Cf. Beebe (forthcoming b) and Wrenn (2006) for further discussion of the problems and prospects of modal frequentism.
I am grateful to an anonymous reviewer from Philosophia for encouraging me to address the possibility that BonJour and other abductivists could adopt a Keynesian interpretation of probability.
According to modal frequentism, probabilistic relations between propositions are based upon relations those propositions have to various worlds and the relations that obtain between sets of those worlds. Thus, the relations that obtain between these propositions will not be ‘internal’ i.e., they will not hold necessarily because of the nonrelational properties of the propositions.
One difficulty BonJour must overcome is that – at least according to Fumerton (1995, 201) – a Keynesian conception of probability “loses that necessary connection between epistemic rationality and truth.” This alleged fact clashes sharply with BonJour’s deep-seated beliefs about the relation between justification and truth. Cf. “Metatheoretic Constraints” section for further discussion of BonJour’s views on this matter.
BonJour (1985, 157) writes:
The basis for this [metajustification] requirement is simply but also extremely compelling: truth is the essential, defining goal of cognitive inquiry, and thus any sort of justification which was not in this way truth-conducive would be simply irrelevant from the standpoint of cognition, whatever its other virtues might be. It would not be epistemic justification, and there would be no reason for a person whose goal is truth to accept beliefs according to its dictates.
BonJour (1998, 91) supports this claim with the following line of thought:
What reason can be offered for thinking that a system of beliefs which is simpler, more conservative, explanatorily more adequate, etc., is thereby more likely to be true, that following such standards is at least somewhat conducive to finding the truth? Someone who had not rejected the possibility of a priori justification might attempt to offer an a priori argument for the truth-conduciveness of at least some of these standards.... But Quine has in any case ruled out such an appeal. Moreover, it is clear at once that any attempt at an empirical argument for this sort of conclusion would inevitably be question-begging, since it would have to appeal to at least some of these very standards.
BonJour (2002, 266) also claims that “naturalized epistemology seems at bottom to concede everything that the skeptic wants, while avoiding this appearance only by changing the subject.”
BonJour (1998, 96) also suggests that “externalism, like naturalized epistemology, seems to simply change the subject without really speaking to the issues that an adequate epistemology must address.” In earlier work, BonJour (1985, 58) wrote that externalist theories invoke the following:
external justifying conditions which need not be at all within the ken of the knowing subject. But the price of such a view is the abandonment of any claim that this subject himself has any reason for accepting the basic belief and thus seemingly also of the claim that he is justified in holding either that belief or others which depend on it. In this way, the externalist view collapses into skepticism.
I am indebted to an anonymous reviewer from Philosophia for helping me avoid a serious blunder in my discussion of the issues in this section.
In a footnote BonJour (2003, 23, n. 19) also mentions the following, third difficulty: knowledge cannot be identified with true belief justified to any degree of justification less than the maximum because no such account will be Gettier-proof. In other writings BonJour (2002, 47) notes that any conception of knowledge that requires less than conclusive justification will also give the wrong verdict in lottery cases.
For example, many relevant alternatives, externalist and neo-Moorean accounts of knowledge require that one’s grounds be conclusive in order to have knowledge. All such theories attempt to avoid both of the problems BonJour describes.
I am grateful to an anonymous reviewer from Philosophia for getting me to address the issues in this section more squarely than I had done before.
But cf. Beebe (forthcoming a) for detailed discussion of the seriousness of the potential threat of a priori skepticism.
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Acknowledgement
I would like to thank two anonymous reviewers from Philosophia and audiences at the University at Buffalo and the 2006 meeting of the Society for Skeptical Studies for helpful comments and suggestions on earlier drafts of this paper.
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Beebe, J.R. BonJour’s Abductivist Reply to Skepticism. Philosophia 35, 181–196 (2007). https://doi.org/10.1007/s11406-007-9055-y
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DOI: https://doi.org/10.1007/s11406-007-9055-y