Abstract
According to global skepticism, we know nothing. According to local skepticism, we know nothing in some particular area or domain of discourse. Unlike their global counterparts, local skeptics think they can contain our invincible ignorance within limited bounds. I argue that they are mistaken. Local skepticism, particularly the kinds that most often get defended, cannot stay local: if there are domains whose truths we cannot know, then there must be claims outside those domains that we cannot know even if they are true. My argument focuses on one popular form of local skepticism, ethical skepticism, but I believe that the argument generalizes to cover other forms as well.
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Notes
For statements of global skepticism, see, e.g., Descartes, Meditations I; Peter Unger, Ignorance: A Case for Scepticism (Oxford: Oxford University Press, 1975, 2002); and Keith Lehrer, “Why Not Skepticism?” The Philosophical Forum 2 (1971): 289–298.
“Scepticism, ‘Externalism’, and the Goal of Epistemology,” Aristotelian Society Supplementary Volume 68 (1994): 291–307; 291.
Skepticism: The Central Issues (Oxford: Blackwell Publishers Ltd., 2002), pp. 11, x.
Some skeptics deny the existence of epistemically justified beliefs rather than knowledge, but for simplicity I will concentrate on the denial of knowledge. If, as epistemologists have often maintained, knowledge implies justification but not conversely, then knowledge-denying skepticism is logically weaker than justification-denying skepticism: the latter implies the former but not conversely. Thus, my decision to focus on knowledge makes my case against local skepticism harder rather than easier, since all else equal a logically weaker position is harder to refute. In any case, one can adapt my argument to address justification-denying skepticism without loss of plausibility.
See, e.g., J. L. Mackie, Ethics: Inventing Right and Wrong (New York: Penguin, 1977).
Nihilism and skepticism may differ as a stronger proposition differs from a weaker one: If a given domain contains no truths at all, then of course no one knows any truths from the domain, but not conversely. Indeed, skepticism concerning a given domain is at best trivial if combined with the nihilistic view that no propositions in the domain are true. The solipsist, for instance, finds skepticism about the external world uninteresting because she finds it trivially true: “if everything that exists existed only in my own mind, Descartes’s scepticism would lose its sting. It would be no limitation on my knowledge that I did not know of the existence of anything independent of me if there were nothing independent of me” (Stroud, The Significance of Philosophical Scepticism [Oxford: Clarendon Press, 1984], p. 129). Perhaps, instead, the two positions are incompatible, as Jonathan Dancy suggests in the context of ethics: “In ethics there is, of course, the view that there are no moral facts to be known or believed at all. This is commonly called moral scepticism, but it should not be, for if there are no relevant facts there is nothing to be ignorant of ....” (“Moral Epistemology,” A Companion to Epistemology, ed. Jonathan Dancy and Ernest Sosa [Oxford: Blackwell, 1992], p. 286). Perhaps, instead, the positions are logically independent of each other.
Paul Helm, Belief Policies (Cambridge: Cambridge University Press, 1994), 197.
I do not mean to imply that ∼p is an ethical proposition whenever p is an ethical proposition; in fact, I believe the contrary: ∼p is never an ethical proposition if p is an ethical proposition. I claim, instead, that it is plausible to regard E, in particular, as an ethical proposition only if it is plausible to regard ∼E as an ethical proposition. In my view, neither E nor ∼E is an ethical proposition.
The modifier “distinctively” is important. The proposition “There are planets,” while accepted by astrologers, is not a distinctively astrological proposition, because orthodox astronomy (among many other discourses) also contains it. By contrast, “One’s Sun sign influences one’s personality” is distinctively astrological, because other kinds of discourse do not contain it. The proposition “The world exists” is commonsensical, not distinctively theological, whereas “God made the world” is distinctive of theology; “God exists, or God does not exist” is logical, not theological, while “God exists” is theological.
Some contend that non-nihilism about a domain belongs to the domain if and only if it is true. I reply to this implausible contention in “Moral Conclusions from Nonmoral Premises,” forthcoming in Hume, ‘Is’ and ‘Ought’, ed. Charles Pigden (Palgrave Macmillan).
Proposition W disjoins a “second-order” semantic claim with a “first-order” ethical claim; if such a combination seems logically illicit, we can replace W with a disjunction of two semantic claims. (W′) No ethical proposition is true, or “Torturing babies just for fun is wrong” is true. Modifying the rest of the argument accordingly.
Among non-nihilists, consequentialists will accept W because they think recreational baby-torture produces a net balance of unfavorable over favorable consequences, to say the least. Deontologists will accept W because they think that we have a duty not to torture babies just for fun; or that torturing babies just for fun involves treating humanity merely as means or violating another form of the categorical imperative; or that it (further) brutalizes the torturer. What about the particular kind of deontologists known as “divine-command” theorists? Might they reject W? Now, not everyone accepts every highly probable claim, and so W can be highly probable even if divine-command theorists reject it. But my hunch is that divine-command theorists would in fact accept W. They believe that, if God exists (or were to exist), then surely God has willed (or would will) that we not torture babies just for fun. Even hedonistic act-utilitarians, who allow that some torturers might derive enough pleasure from baby-torture to outweigh the suffering it causes, will accept W if “wrong” is construed as “defeasibly wrong.”
If this usage of the term does not fit some who call themselves “noncognitivists,” consider it a merely stipulative usage.
Here is the proof more formally. As before, let “∼E” represent ethical nihilism, and let “B” abbreviate “W belongs to the domain of ethics”:
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(1)
∼◇((W & ∼E) & B)
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(2)
◇(W & ∼E)
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(3)
Therefore: ◇∼B [From (1), (2)]
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(4)
◇∼B ⊃ ∼B
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(5)
Therefore: ∼B [From (3), (4)]
Premise (1) is uncontroversial. Premise (2) presupposes that (a) W is logically possible and (b) ∼E is logically possible. If not (a), then no one can consistently accept wedge claims; if not (b), then nihilists cannot consistently accept anything, including nihilism. Presumably, (a) implies that noncognitivism is not necessarily true, since noncognitivism implies that W is not true (because neither true nor false).
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(1)
This assumption has been challenged; see Toomas Karmo, “Some Valid (But No Sound) Arguments Trivially Span the ‘Is’–‘Ought’ Gap,” Mind 97 (1988): 252–257; I. L. Humberstone, “A Study in Philosophical Taxonomy,” Philosophical Studies 83 (1996): 121–169; 158 n.32. These challenges fail, as I argue in “Closing the ‘Is’–‘Ought’ Gap,” Canadian Journal of Philosophy 28:3 (1998): 349–366, and in “Moral Conclusions from Nonmoral Premises.”
“Relevant” logicians may reject the deduction because it relies on disjunctive syllogism, which they regard as invalid. But they are hardly skeptics about deduction: they do not think that we simply fail to know that disjunctive syllogism is valid.
On the contrary, I offer evidence against epistemic closure in “The Knower Paradox and Epistemic Closure,” Synthese 114:2 (1998): 337–354.
For a defense of this claim, see “Moral Conclusions from Nonmoral Premises.” Unfortunately, the non-ethical status of a disjunction such as C is not as easy to establish as the non-ethical status of a wedge claim such as W, which explains the need for wedge claims in my case against local skepticism.
John Schellenberg has suggested to me an independent reason for rejecting assumption (1): not every disjunction of ethical propositions is “action-guiding”; if an ethical proposition must be action-guiding, then an infinite disjunction of ethical propositions will probably not itself be an ethical proposition.
Does Gödel’s theorem then imply a stable form of local skepticism about the domain “arithmetically unprovable statements of arithmetic”? Not unless knowledge of any arithmetical truth requires its provability within arithmetic, a quite doubtful assumption; for without that assumption, the wedge claim “The domain contains no truths, or [insert paradigm] is true” will not imply the clearly false disjunction “The domain contains no truths, or [insert paradigm] is provable.” Moreover, such Gödelian local skepticism is more arcane and artificial than the kinds of local skepticism that possess what Landesman (note 3 above), calls “vast cultural significance.” By the same token, local skepticism about the domain of unknowable truths (assuming that domain is non-empty) is trivially immune to my attack, but it attracts no skeptical interest since of course no one has ever wanted to claim knowledge in a domain thus labeled—everyone must be a “skeptic” about that domain.
“Scepticism, ‘Externalism’, and the Goal of Epistemology,” p. 291.
See again note 20 and Section 2: “Non-Nihilism.”
For many helpful comments, I thank Andrew Graham, Christoph Kelp, and audiences at Acadia University, Dalhousie University, and the University of Stirling.
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Maitzen, S. The Impossibility of Local Skepticism. Philosophia 34, 453–464 (2006). https://doi.org/10.1007/s11406-007-9047-y
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DOI: https://doi.org/10.1007/s11406-007-9047-y