148 Three Source Incompatibilist Arguments
is designed to establish is that a certain sort of freedom is not required for moral
responsibility; it says nothing about how to account for the sort of freedom that
is required. A significant number of incompatibilists have endorsed Frankfurt’s
argument, accepting that we must attend to source freedom in our theorizing
about free will and moral responsibility. They also argue that the sort of source
freedom required for moral responsibility is incompatible with determinism.
Accordingly, source theorists divide into source compatibilists and source
incompatibilists.^3 They are united in accepting Frankfurt’s argument (or some
argument to the same conclusion) and thus taking the Consequence Argument
and similar variants to be beside the point. Contemporary leeway theorists, by
contrast, divide into leeway compatibilists and leeway incompatibilists.^4 They
agree on taking seriously the centrality of the Consequence Argument, or an
appropriately similar argument, as at the heart of their dispute. To complicate
matters a bit more, Seth Shabo (2010a) usefully distinguishes two kinds of
source incompatibilism: (1) the compromising view defended by Kane (1996),
for whom robust alternative possibilities are required for moral responsibility
because—but only because—they are required for ultimate sourcehood; and (2)
the uncompromising view, held by most of the other source incompatibilists,
according to which robust alternative possibilities are not required for ultimate
sourcehood. Rather, the only alternative possibilities required on this view are
those that are entailed by the falsity of determinism (Della Rocca, 1998; Pere-
boom, 2001).
Given the preceding dialectical “redistricting” occasioned by Frankfurt’s
argument, one can now begin to appreciate how the newly emerging dialectical
burdens have changed. Leeway theorists remain committed to tending to the
Consequence Argument. As a result, that argument has remained a significant
influence on philosophers currently advancing some version of a leeway theory
of freedom—whether they are incompatibilists or compatibilists. Given this per-
spective, incompatibilists should assume the burden of defending some variant
of this argument, or instead some relevantly similar argument that promises to
do better. Compatibilists shoulder the burden of rejecting it. But what about the
dialectical burdens of source theorists of various sorts? In one respect source
compatibilists have a dialectical advantage over leeway compatibilists: They do
not have to take on the burden of explaining the freedom to do otherwise under
the assumption that determinism is true. Still, they must offer some positive
account of source freedom all the ingredients of which are compatible with
determinism.
Given the source view, incompatibilists need to show why we should think
that determinism rules out a relevant kind of source freedom. In light of the
source incompatibilists’ burdens, they are apt to endorse what earlier (Section
3.3) we called the Basic Source Argument for Incompatibilism (BSI):
- A person acts of her own free will only if she is its ultimate source.
- If determinism is true, no one is the ultimate source of her actions.
- Therefore, if determinism is true, no one acts of her own free will.