Against Parthood∗ - Ted Sider

consistent with common sense are preferable to those that contradict common
sense; common sense is an epistemic difference-maker. According to some it is
nearly decisive; according to others it is one factor among many. Either way,
Mooreanism seems to give us an (at least prima facie) argument against nihilism,
since the existence of tables, chairs, and other composites is as commonsensical
as it gets.
But on the face of it, Mooreanism is utterly implausible. Why should the
inherited prejudices of our forebears count for anything?
We should, of course, trust common sense in some particular domain if
there is independent reason to think that it is reliable about that domain. But
there is no independent reason to think that common sense is reliable about
whether there exist tables and chairs as opposed to there merely existing suitably
arranged particles. Our forbears presumably did not even consider the latter
possibility. After all, the issue is a subtle one, makes little practical difference,
and can even seem empty (see section 8). 24 The Mooreanism I oppose says that
we should trust common sense even in the absence of independent reason to
think that it is reliable. And that seems no better than the absurd: “believe the
masses”.
Why are so many metaphysicians Mooreans? Partly because they fear that if
we reject common sense, there will not be enough to go by. 25 Both metaphysics
and inquiry generally, it is thought, would be paralyzed. Without Mooreanism,
we could not reply to the external-world skeptic, for example; we could not dig
in our heels and say: of course there is an external world!
But again a flat-footed answer tempts. The dictates of common sense are
often independently reasonable, and when they are, they do not need backing
from common sense. Reason can stand on its own.
Consider, for example, Russell and Quine’s answer to the external-world
skeptic: it is reasonable to posit a world of external objects because this posit
best explains our sensory experiences. 26 However exactly we cash out the notion
be conceived in this way, but this does not prevent us from recognizing other norms that are
conceived differently. In foundational inquiries, for example, such as those undertaken by
philosophers, we submit ourselves to demands that would be out of place in ordinary epistemic
life, in full realization of the practical difficulties of doing so. Even a conservative might admit
that in foundational contexts—such as the one we are in now—we cannot decline the re-think
on the grounds that it would be too disruptive. In such contexts, we are governed by norms of
reasoning that are less practical, more ambitious (though perhaps quixotic).
24 I would also stress these facts in an answer to Korman’s (2009) problem of reasonableness.
25 See, e.g., Zimmerman (2007).
26 Russell (1912); Quine (1948). See also Vogel (1990).
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