22 Free Will, Moral Responsibility, Determinism
kids to school this morning given the entirety of the facts of the past and all of
the laws of nature. But this conditional necessity is not at all the same as an
unconditional claim that it is necessary that Dana drive her kids to school this
morning.
One reason that people commit the preceding fallacy is because they are
implicitly assuming something that, if true, would validly yield the conclusion
that, necessarily, Dana drove her kids to school this morning. They are assuming
that it is metaphysically necessary that the past is what it is and that the laws of
nature are metaphysically necessary as well. But this is not part of or a con-
sequence of the thesis of determinism. It is fully consistent with the truth of
determinism that the past is only contingently as it is. It could have been differ-
ent. It just wasn’t. The same applies to the laws of nature. The laws of nature
might not be alterable by human beings, but it is consistent with there being laws
of nature that it is a metaphysically contingent fact about this universe that the
laws of nature are what they are. It is metaphysically possible, on this view, that
the laws of nature might have been different from what they are. The speed of
light, for instance, might have been a little faster or instead slower than what it
actually is. The fact that the laws of nature are general and nonaccidental, excep-
tionless truths about this universe is not sufficient to conclude that it is not meta-
physically possible that this universe have instead featured some different set of
general and nonaccidental exceptionless truths.
Furthermore, while it is physically impossible in one sense for the future to
be other than as it is (or will be) under the assumption of determinism, it might
very well be possible, say nomically possible, that some feature of the present or
future be other than as it was. Dana, for instance, might not have driven her kids
to school this morning if her past had been slightly different from what it was,
holding the laws fixed. Suppose, for instance, that Sam happened to note early in
the morning that he had to pass by the school today for some other reason. Had
that been a part of Dana’s past, she might not have taken her kids to school even
if the laws were the same as they actually are. This scenario is therefore nomi-
cally possible. Determinism only renders it metaphysically necessary that she
took her kids to school this morning given the entirety of the actual past and the
totality of the actual laws of nature. It does not impugn the metaphysical or
nomic possibility of her not taking the kids to school instead.
Without distinguishing unconditional from conditional metaphysical neces-
sity and possibility, metaphysical from physical necessity and possibility, and
physical from nomic necessity and possibility, it’s hard to keep track of these
claims, and also of some of the more sophisticated theses that will arise in chap-
ters to follow. For instance, some compatibilist theses contending that the ability
to do otherwise is compatible with determinism are difficult to understand
without tending to these modal issues. We wish to emphasize here that notions
of necessity and possibility are intricately layered, and keeping this in mind is
important for understanding some of the key moves in the free will debate.