Materialism is the hypothesis that
nothing exists except matter and that nothing happens except the motion of that
matter. (Of course, materialists can also acknowledge the existence of the
space and time matter needs to be and move in; they might also admit the
existence of abstract objects such as numbers.) Physicalism is a special brand
of materialism; it is the hypothesis that nothing exists except the
things studied by the science of physics and that nothing happens except in
accord with the laws of physics. Thus, in principle, physics textbooks could
provide a complete account of everything; By means of this latter
formulation, Andrew Melnyk, the author of A Physicalist Manifesto,
achieves an admirable degree of clarity while remaining true to the spirit of
materialism.

It is important to realize that
materialism could be true even if physicalism were false: it is one thing to
say that there is nothing but matter — that there are no angels, spirits, or
gods — but quite another to say that one science, the science of
physics, manages to describe and explain everything that exists or
happens. Indeed, not so very long ago, most biologists firmly believed
that the mechanisms of physics could not possibly account for the nature of
living organisms, even though they also believed that our bodies are material
things (no angels or spirits were thought to be hovering about in our
kidneys).  It was assumed that because life constantly displays purposes — the
heart is for pumping blood, the lungs are for inhaling oxygen —
while physics deals only with chunks of matter pushing and pulling each other
around, physics could not possibly say much about life. Today, there are
psychological theorists who deny that physical science can ‘cover’ anything of
interest to them because there is no way to make the concepts of physics
and psychology ‘mesh’. Some philosophers of science maintain that reality
itself is ‘messy’, that it doesn’t really ‘fit together’ in any neat unified
way that would permit the unity of science with physics as the great unifier.
Such considerations partly account for what must be called the loathing
of ‘reductionism’. (Reductionism is the belief that, for example, the
generalizations of psychology can, in principle, be restated as generalizations
of physics.) 

If physicalism is to be a
respectable hypothesis, it must be able to answer, at least, the following four
questions; it is not clear that it can. First, there is the problem of what we
take ‘physics’ to be. Physics has changed much through the years and will
continue to do so. Thus, if we say that everything that exists can be accounted
for in terms of the entities and laws of physics, it is not clear what we are
saying. Are we predicting that some day physics will encompass everything?
Might physics so change as to come to include concepts such as purpose, just as
it came to accept action at a distance or probabilistic transitions? It appears
that whenever it is pointed our that physics cannot account for something, the
physicalist can reply that all we need do is wait for some better physics in
the future Physicalism seems to lack any firm content. Second, can physics
‘cover’ the ‘special sciences’ such as geology and psychology? If so, what is
the point of the special sciences and why do they seem  — are — so
indispensable? Third, and closely related to the last question, does the
empirical evidence available actually support the hypothesis that one science,
physics, can cover everything. Fourth, there is the traditional problem for any
form of materialism: How could consciousness be the nothing but matter in
motion?

Andrew Melnyk tries to answer these
questions, and thereby defend physicalism, in this extremely good book. His
approach is systematic, painstaking, and as clear as the material allows; the
scope of his knowledge is impressive and skillfully deployed; his arguments are
cogent and will be hard to refute. Clearly, the problem of delineating the
relationship between physics and the special sciences has very broad relevance;
it is more general, but of a piece with the familiar problem of delineating the
proper relationship between cognitive science and neuroscience. Thus, it is
unfortunate that this book will probably be readily comprehensible only to
philosophers and to scientists who are well aware of the philosophical issues.
On the other hand, given the fact that philosophy has no shallow end anyway,
this book, given its scope and clarity, might serve as quite a good
introduction to the topic of ‘the unity of science’ for anyone who is
determined to seriously work through it.

Perhaps, I would do well to mention
what I found the most interesting aspect of Melnyk’s work, and that which I
think most enables him to make real progress in answering many of the most
difficult questions physicalism must answer if it is to remain a viable
hypothesis, questions such as those mentioned two paragraphs above: It is his
uncompromising ‘naturalism’.  Naturalism, among other things, maintains that natural
science sets the limit to what we can know about reality; philosophy cannot go
‘beyond’ it.  This requires some (very partial) explanation. Ever since science
became a distinct, recognizable activity, most philosophers have believed that
philosophy and science are quite different enterprises; indeed, it has been
common to believe that philosophy cannot be science because it has to
provide a foundation for science. It is thus concluded that philosophy
must have a special proprietary subject matter, a subject matter that can and
must be studied by special proprietary methods that are necessarily a priori.
Thus, to continue this line of thought, philosophy can have no use for
empirical data; rather, it must be something like a close inward inspection of
our ideas, or an a priori study of how we use certain words, or an analysis of
our concepts. There is another approach to philosophy, one that sees philosophy
as continuous with science, differing only in that it works at very high level
of abstraction, seeking, as Wilfred [CHECK!!!] Sellars put it, to understand
"how things, in the broadest sense, fit together." This is Melnyk’s
stated position, and armed with it, he can answer some of the difficult
questions that confront physicalism. For example, as mentioned above, there is
the problem of specifying what we take ‘the physical’ to be. Melnyk finesses
this difficulty by abjuring the search for some given, necessary, a priori
determinable essence of the ‘physical’ by saying, simply, that ‘the
physical’ is what physics textbooks talk about; the problem of scientific
growth and change is dealt with by simply saying that whatever the physicists
do will still define the physical; we need not worry about what some
contemporary analysis of the ‘meaning’ of ‘physical’ might come up with. He
also avoids such problems as whether certain things that do not exist, but
possibly could, would meet his criterion for being physical by simply limiting
his interest to those things that actually do exist — after all, that is the
real issue for physicalism, and it is an empirical issue as is the truth of
physicalism itself.  Moreover, and unlike almost all philosophers, he actually
presents empirical evidence for physicalism, explaining why it is indeed
evidence, and he shows the faults of supposed empirical results that supposedly
support physicalism, such as are found in the claims of parapsychology. .

In conclusion, this is an excellent
book and will no doubt become a must-read for anyone seriously thinking about
the issue of scientific unity.

© 2005 Alan N. Sussman

Alan N. Sussman
received his Ph.D. in philosophy from the University of Chicago. He has published a few papers, including one in The
Journal of Philosophy. He taught philosophy at various colleges and
universities in the US and Africa. At present he teaches part time at Truman College, Chicago. His
philosophical interests are primarily in philosophy of mind.

Categories: Philosophical