36 The Free Will Problem
It seems reasonable to think that the verdict is still out, that consistent with what
we now know about the arrangement of the natural world whether determinism
is true or false remains to be established.
Let us approach the question of the truth of determinism from another angle.
One way to begin to appreciate determinism’s appeal is to consider the Principle
of Sufficient Reason, a principle that has its roots in philosophers like Leibniz.
The principle is often expressed in different ways, but in its simplest form it is
the thesis that there is a sufficient reason for everything to be as it is and not
otherwise (Hoefer, 2010). Determinism would have it that for each state of the
world at any time, there are causal processes involving the past and the laws that
guarantee that it is that way. There would then be facts about the past and the
laws that explain why it is that way and no other way. And by contrast, indeter-
minism would have it that there are states of the world at a time for which there
are no causal processes involving the past and the laws that guarantee that they
are that way, and no corresponding explanations. Some philosophers and physi-
cists find this puzzling.
These considerations alone still do not show that determinism is itself highly
likely to be true, but if we are willing to expand the thesis to include almost-
determinism, in terms of either mechanism or naturalism (as defined in the
previous chapter), then something very much like determinism does start to seem
quite credible. For instance, in the form of mechanism, the physical states of
human beings, combined with the laws of nature, might roughly determine only
one significant course of action for any normally functioning human person,
even if, at the microphysical level, the various states of an agent’s body, and in
particular her brain, allow for minor variations in how those significant courses
of action are realized. Perhaps philosophers continue to make use of the strict
definition of determinism (requiring only one unique future) because it allows
them to formulate the philosophical problems, arguments, and theories more rig-
orously. For the most part, the formulations could be captured when determinism
is expressed more loosely. It is just that it would be more cumbersome.
So it seems that determinism, when meant to include the looser notions of
almost- determinism, mechanism, or naturalism, is plausible. It is plausible
because it resonates with a scientific conception of the natural order, a conception
in which all aspects of nature can (at least in theory) be accounted for in terms of
physical states, processes, and events behaving according to natural laws. This
conception of the natural order is invited by an ever- expanding body of scientific
knowledge capable of explaining a vast and diverse range of phenomena, includ-
ing the state and behavior of human beings. Naturally, the fact that much of
human conduct can be explained by appeal to resources that fit within larger sci-
entific theories does not amount to the claim that all human behavior is deter-
mined, but it does make plausible the thesis that it might be, at least to the extent
that the theories of explanation are (again, put loosely) deterministic.
But is there value in attempting to preserve determinism against threats to it?
According to the incompatibilist thesis, free will threatens determinism just as
much as determinism threatens free will. In particular, if one had good reason to