86 The Debate over the Consequence Argument
That is, from the fact that that no one has, or ever had, a choice about whether p
is true, and that no one has, or ever had, a choice about whether p implies q, one
can validly infer that no one has, or ever had, a choice about whether q is true.
Next, van Inwagen (94) introduces names for two key propositions. One, Po,
names a proposition that expresses a complete state of the actual world at some
time in the remote past. Another, L, names a proposition detailing the actual
laws of nature. Finally, P is used to name a proposition about some actual state
of affairs at some later time. Van Inwagen selects the proposition that Richard
Nixon was pardoned for any crimes he committed while he was President of the
United States (94–5), and we’ll follow him in treating this as P.
Now, it follows from determinism being true that it is metaphysically neces-
sary that P is implied by the conjunction of Po and L, and this entailment can be
formulated as follows (94–5):
□((Po&L) → P)Two further assumptions, the Principle of the Fixity of the Past and the Principle
of the Fixity of the Laws, as applied to Po and L, yield premises that figure in the
argument. Each is expressed by making use of the power necessity operator “N”:
NPo (No one has, or ever had, a choice about whether Po is true.)NL (No one has, or ever had, a choice about whether L is true.)Van Inwagen introduces these two power necessities separately, and not as a single
premise N(Po&L), by contrast with how we presented it above (in Section 4.2).
Readers might have noticed that in our earlier formulation, we simply left it
as intuitive that if the metaphysical thesis of determinism is true, it is power
necessary for a person.^15 That is, in Section 4.2, we began with this assumption:
N((p&l) → f )In doing so, we did not offer any argument for it. But with van Inwagen’s Rule
α, applying it to the above proposition about pardoning Nixon, the relevant pro-
position can be derived as follows:
- □((Po&L) → P)
- Therefore, N((Po&L) → P) from Rule α
As we explained earlier (Section 1.4), determinism is a thesis that involves meta-
physical necessity: If determinism is true, then it is metaphysically necessary
that ((Po&L) → P), i.e., that the past and laws entail all other facts about what
happens at that world. Rule α licenses inferring the power necessity of
((Po&L) → P) from its metaphysical necessity.^16
It bears mentioning that the propositions NPo and NL differ from the pro-
position N((Po&L) → P) in that they are not derived, by way of Rule α, from a