Timothy Williamson |
By Timothy Williamson, The New York Times, September 3, 2011
Many contemporary philosophers describe themselves as
naturalists. They mean that they believe something like this: there is only the
natural world, and the best way to find out about it is by the scientific
method. I am sometimes described as a naturalist. Why do I resist the
description? Not for any religious scruple: I am an atheist of the most
straightforward kind. But accepting the naturalist slogan without looking
beneath the slick packaging is an unscientific way to form one’s beliefs about
the world, not something naturalists should recommend.
What, for a start, is the natural world? If we say it is
the world of matter, or the world of atoms, we are left behind by modern
physics, which characterizes the world in far more abstract terms. Anyway, the
best current scientific theories will probably be superseded by future scientific
developments. We might therefore define the natural world as whatever the
scientific method eventually discovers. Thus naturalism becomes the belief that
there is only whatever the scientific method eventually discovers, and (not
surprisingly) the best way to find out about it is by the scientific method.
That is no tautology. Why can’t there be things only discoverable by
non-scientific means, or not discoverable at all?
Still, naturalism is not as
restrictive as it sounds. For example, some of its hard-nosed advocates
undertake to postulate a soul or a god, if doing so turns out to be part of the
best explanation of our experience, for that would be an application of
scientific method. Naturalism is not incompatible in principle with all forms of
religion. In practice, however, most naturalists doubt that belief in souls or
gods withstands scientific scrutiny.
What is meant by “the scientific method”? Why assume
that science only has one method? For naturalists, although natural sciences
like physics and biology differ from each other in specific ways, at a
sufficiently abstract level they all count as using a single general method. It
involves formulating theoretical hypotheses and testing their predictions
against systematic observation and controlled experiment. This is called the
hypothetico-deductive method.
One challenge to naturalism is to find a place for
mathematics. Natural sciences rely on it, but should we count it a science in
its own right? If we do, then the description of scientific method just given
is wrong, for it does not fit the science of mathematics, which proves its
results by pure reasoning, rather than the hypothetico-deductive method.
Although a few naturalists, such as W.V. Quine, argued that the real evidence
in favor of mathematics comes from its applications in the natural sciences, so
indirectly from observation and experiment, that view does not fit the way the
subject actually develops. When mathematicians assess a proposed new axiom,
they look at its consequences within mathematics, not outside. On the other
hand, if we do not count pure mathematics a science, we thereby exclude
mathematical proof by itself from the scientific method, and so discredit
naturalism. For naturalism privileges the scientific method over all others,
and mathematics is one of the most spectacular success stories in the history
of human knowledge.
Which other disciplines count as science? Logic?
Linguistics? History? Literary theory? How should we decide? The dilemma for
naturalists is this. If they are too inclusive in what they count as science,
naturalism loses its bite. Naturalists typically criticize some traditional
forms of philosophy as insufficiently scientific, because they ignore
experimental tests. How can they maintain such objections unless they restrict
scientific method to hypothetico-deductivism? But if they are too exclusive in
what they count as science, naturalism loses its credibility, by imposing a
method appropriate to natural science on areas where it is inappropriate. Unfortunately,
rather than clarify the issue, many naturalists oscillate. When on the attack,
they assume an exclusive understanding of science as hypothetico-deductive.
When under attack themselves, they fall back on a more inclusive understanding
of science that drastically waters down naturalism. Such maneuvering makes
naturalism an obscure article of faith. I don’t call myself a naturalist
because I don’t want to be implicated in equivocal dogma. Dismissing an idea as
“inconsistent with naturalism” is little better than dismissing it as
“inconsistent with Christianity.”
Still, I sympathize with one motive behind naturalism —
the aspiration to think in a scientific spirit. It’s a vague phrase, but one
might start to explain it by emphasizing values like curiosity, honesty,
accuracy, precision and rigor. What matters isn’t paying lip-service to those
qualities — that’s easy — but actually exemplifying them in practice — the hard
part. We needn’t pretend that scientists’ motives are pure. They are human. Science
doesn’t depend on indifference to fame, professional advancement, money, or
comparisons with rivals. Rather, truth is best pursued in social environments,
intellectual communities, that minimize conflict between such baser motives and
the scientific spirit, by rewarding work that embodies the scientific virtues.
Such traditions exist, and not just in natural science.
The scientific spirit is as relevant in mathematics,
history, philosophy and elsewhere as in natural science. Where experimentation
is the likeliest way to answer a question correctly, the scientific spirit
calls for the experiments to be done; where other methods — mathematical proof,
archival research, philosophical reasoning — are more relevant it calls for
them instead. Although the methods of natural science could beneficially be
applied more widely than they have been so far, the default assumption must be
that the practitioners of a well-established discipline know what they are
doing, and use the available methods most appropriate for answering its
questions. Exceptions may result from a conservative tradition, or one that
does not value the scientific spirit. Still, impatience with all methods except
those of natural science is a poor basis on which to identify those exceptions.
Naturalism tries to condense the scientific spirit into a
philosophical theory. But no theory can replace that spirit, for any theory can
be applied in an unscientific spirit, as a polemical device to reinforce
prejudice. Naturalism as dogma is one more enemy of the scientific spirit.
Timothy
Williamson is the Wykeham Professor of Logic at Oxford University, a Fellow of
the British Academy and a Foreign Honorary Member of the American Academy of
Arts and Sciences. He has been a visiting professor at M.I.T. and Princeton.
His books include “Vagueness” (1994), “Knowledge and its Limits” (2000) and
“The Philosophy of Philosophy” (2007).
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