The Debate over the Consequence Argument 93Applying this to Jimmy Olson (jo) on the first day of the year 2000 (1/1/00), we
get the proposition:
Jjo, 1/1/00, (r) = On New Year’s Day of 2000, Jimmy Olson is justified in
believing that Superman is Clark Kent.Grant that Jjo, 1/1/00, (r) is true. But changing the indexing can alter the truth of the
proposition, so that, if Lois Lane (ll) were substituted for Jimmy Olson, (Jll, 1/1/00,
(r)), the distinct proposition represented here would be false, assuming that our
dear Lois remains unaware that her beloved Superman is after all Clark. Like-
wise, if we preserved the indexing to Jimmy Olson, but changed the time index-
ing to December 1, 1999, as in Jjo, 12/1/99, (r), we would also get a false proposition
rather than a true one.
The modality of concern for our topic, power necessity, concerns the truth of
propositions that are not within a person’s power to alter at certain times, such as
the relation that a person of today stands to the proposition that Caesar crossed
the Rubicon in 49 bc. Let us represent the power necessity modality with an
operator represented by the capital letter N. Now, indexed to Barack Obama
(bo), in the year 2013 ( 13 ), and the proposition that Caesar crossed the Rubicon
(q), we get the proposition, Nbo,13 (q), which can be read as “It is power neces-
sary for Barack Obama in the year 2013 that the proposition, ‘Caesar crossed the
Rubicon,’ obtains.” This can in turn be read as: “The proposition, ‘Caesar
crossed the Rubicon,’ obtains, and Barack Obama, in the year 2013, is not free
to act in such a way that, if he were to so act, the proposition, ‘Caesar crossed
the Rubicon,’ would not obtain.”
Appendix II: Ginet’s Challenge to Compatibilist-
Friendly Semantics for Ability
Carl Ginet, who early on formulated a version of the Consequence Argument
(1966), defends this argument against objections that deny the fixity of the laws
and the fixity of the past (1990).
Let’s consider first the compatibilist who denies the fixity of the past. Ginet
argues that it’s intuitive that to be able to do something is to be able to add to the
given past, that is, to add some event to the past as it has been given. Now
suppose that an agent S does not perform action a at time t, that is, not- at; and
that there is some event b that occurs before t, bt, such that:
BT: If it had been the case that at, then it would have been the case that
not- bt.That is, if action a had occurred at t instead, then event b would not have
occurred before t. From BT it follows that it was not open to S to make it the
case that (bt&at). Let Ost stand for “it was open for S at t.” The compatibilist
under consideration, who Ginet calls the “compatibilist backtracker,” will now