Alex Rosenberg |
By Alex Rosenberg, The New York Times, September 17, 2011
Naturalism is the philosophical theory that treats
science as our most reliable source of knowledge and scientific method as the
most effective route to knowledge. In a recent essay for The Stone, Timothy
Williamson correctly reports that naturalism is popular in philosophy. In fact
it is now a dominant approach in several areas of philosophy — ethics,
epistemology, the philosophy of mind, philosophy of science and, most of in
all, metaphysics, the study of the basic constituents of reality. Metaphysics is
important: if it turns out that reality contains only the kinds of things that
hard science recognizes, the implications will be grave for what we value in
human experience.
Naturalism is itself a theory with a research agenda of
unsolved problems. But naturalists’ confidence that it can solve them shouldn’t
be mistaken for “dogmatism,” nor can its successes be written off as “slick
packaging,” two terms Professor Williamson used in his essay to describe why he
rejects naturalism.
Before taking up Professor Williamson’s challenges to
naturalism, it’s worth identifying some of this success in applying science to
the solution of philosophical problems, some of which even have pay-offs for
science. Perhaps the most notable thing about naturalism is the way its
philosophers have employed Darwin’s theory of natural selection to tame
purpose. In 1784 Kant wrote, “There will never be a Newton for the blade of grass.”
What he meant was that physical science could never explain anything with a
purpose, whether it be human thought or a flower’s bending toward the sun. That
would have made everything special about living things — and especially us —
safe from a purely scientific understanding. It would have kept questions about
humanity the preserve of religion, mythmaking and the humanities.
Only 25 years or so later, the Newton of the blade of
grass was born to the Darwin family in Shropshire, England. “On the Origin of
Species” revealed how physical processes alone produce the illusion of design.
Random variation and natural selection are the purely physical source of the
beautiful means/ends economy of nature that fools us into seeking its designer.
Naturalists have applied this insight to reveal the biological nature of human
emotion, perception and cognition, language, moral value, social bonds and
political institutions. Naturalistic philosophy has returned the favor, helping
psychology, evolutionary anthropology and biology solve their problems by
greater conceptual clarity about function, adaptation, Darwinian fitness and
individual-versus-group selection.
While dealing with puzzles that vexed philosophy as far
back as Plato, naturalism has also come to grips with the very challenges
Professor Williamson lays out: physics may be our best take on the nature of
reality, but important parts of physics are not just “abstract,” as he says.
Quantum mechanics is more than abstract. It’s weird. Since naturalistic philosophers
take science seriously as the best description of reality, they accept the
responsibility of making sense of quantum physics. Until we succeed,
naturalists won’t be any more satisfied than Professor Williamson that we know
what the natural world is. But 400 years of scientific success in prediction,
control and technology shows that physics has made a good start. We should be
confident that it will do better than any other approach at getting things
right.
The
principles of natural selection are unlikely to be overtaken by events.
Naturalists recognize that science is fallible. Its
self-correction, its continual increase in breadth and accuracy, give
naturalists confidence in the resources they borrow from physics, chemistry and
biology. The second law of thermodynamics, the periodic table, and the
principles of natural selection are unlikely to be threatened by future
science. Philosophy can therefore rely on them to answer many of its questions
without fear of being overtaken by events.
“Why can’t there be things only discoverable by
non-scientific means, or not discoverable at all?” Professor Williamson asked
in his essay. His question may be rhetorical, but the naturalist has an answer
to it: nothing that revelation, inspiration or other non-scientific means ever
claimed to discover has yet to withstand the test of knowledge that scientific
findings attain. What are those tests of knowledge? They are the
experimental/observational methods all the natural sciences share, the social
sciences increasingly adopt, and that naturalists devote themselves to making
explicit. You can reject naturalists’ epistemology, or treat it as question
begging, but you can’t accuse them of not having one.
As Professor Williamson notes, naturalism’s greatest
challenge “is to find a place for mathematics.” The way it faces the challenge
reveals just how undogmatic naturalism really is. It would be easy to turn
one’s back on the problems mathematics presents (What are numbers? How can we
have the certainty about them that math reveals?). One excuse to turn our backs
is that mathematicians and scientists don’t care much about these problems;
another is that no one has ever provided a satisfactory answer to these
questions, so no other philosophy can be preferred to naturalism on this basis.
But naturalism has invested a huge amount of ingenuity, even genius, seeking
scientifically responsible answers to these hardest of questions. Not with much
success as yet by our own standards, one must admit. But that is the nature of
science.
Naturalism takes the problem of mathematics seriously
since science cannot do with out it. So naturalism can’t either. But what about
other items on Professor Williamson’s list of disciplines it would be hard to
count as science: history, literary theory? Can science and naturalistic
philosophy do without them? This is a different question from whether people,
as consumers of human narratives and enjoyers of literature, can do without
them. The question naturalism faces is whether disciplines like literary theory
provide real understanding?
Naturalism faces these questions because it won’t
uncritically buy into Professor Williamson’s “default assumption … that the
practitioners of a well-established discipline know what they are doing, and
use the … methods most appropriate for answering its questions.” If semiotics,
existentialism, hermeneutics, formalism, structuralism, post-structuralism,
deconstruction and post-modernism transparently flout science’s standards of
objectivity, or if they seek arbitrarily to limit the reach of scientific
methods, then naturalism can’t take them seriously as knowledge.
That doesn’t mean anyone should stop doing literary
criticism any more than forgoing fiction. Naturalism treats both as fun, but
neither as knowledge.
What naturalists really fear is not becoming dogmatic or giving
up the scientific spirit. It’s the threat that the science will end up showing
that much of what we cherish as meaningful in human life is illusory.
Alex
Rosenberg is the R. Taylor Cole Professor and philosophy department chair at
Duke University. He is the author of 12 books in the philosophy of biology and
economics. W.W. Norton will publish his latest book, “The Atheist’s Guide to
Reality,” in October.
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