Against Parthood∗ - Ted Sider

out infinite descent in the fundamentality-over-features relation. 57 ) Given
well-foundedness, Conclusion 3 is guaranteed, on independent grounds, to be
false.
10. Possible gunk
So with the possible exception of Arntzenius’s argument, I don’t think there
are good arguments that gunk is actual. But the alleged possibility of gunk is
sometimes thought to threaten nihilism. 58
Gunk is, I suppose, epistemically possible. Maybe scientists will one day
tell us that there is gunk after all; or maybe Arntzenius’s argument will prove
decisive. I don’t pretend to know that these things won’t happen. But defenders
of nihilism can happily grant that nihilism itself is epistemically possibly false.
Substantive metaphysics is not a search for epistemic first principles, compatible
with whatever the future might bring; it can be held hostage to empirical
fortune. This is the price a metaphysician pays for regarding her speculations
as substantive hypotheses about the real world. If the future brings evidence
for gunk, I will reduce my degree of belief in nihilism accordingly.
A quite different threat comes from the alleged “metaphysical” possibility
of gunk. If gunk is metaphysically possible, then nihilism is not metaphysically
necessarily true (let all modalities be understood as metaphysical henceforth).
But nihilism is a “proposition of metaphysics”; and such propositions are
noncontingent; they are necessarily true if true and necessarily false if false. So
nihilism is necessarily false, and so it is actually false. 59 I have no clear definition
of ‘proposition of metaphysics’, but I have in mind propositions about abstract
and general questions that metaphysicians debate, such as “numbers exist”,
“any charged object instantiates the property of being charged”, “time is like
space”, and so on.
The argument from the possibility of gunk faces a challenge. Consider this
argument for the opposite conclusion: “nihilism is possibly true; nihilism is a
proposition of metaphysics and hence is noncontingent; so nihilism is necessarily
true; so nihilism is true”. This argument assumes the possibility of nihilism
57 If one construed fundamentality as applying to facts rather than features, then the assumption
that relative fundamentality is well-founded might prohibit gunk on its own. See Sider
(2011, section 7.7).
58 See, I’m afraid, Sider (1993).
59 The alleged possibility of emergent properties raises some of the same issues.
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