I have been speaking to diverse
small groups about science and religion in the context of the ongoing national debate about the
teaching of evolution in our public schools. The response to my talks has been almost uniformly
positive. It would be useful for other physicists to do as I have been doing.
My audiences have been
service clubs such as Rotary, high-school and college students of science and science journalism,
a school-based community event, a League of Women Voters chapter, a Unitarian church, and a microscopy
club. They have ranged from a dozen to some 60 or 70 people. Access is a problem but not an insuperable
one, since organizations have program chairs hungry for speakers, and local newspapers, especially
small suburban ones, are interested in publicizing such activities.
I am not trying to convert
the convinced anti-evolutionist. I am trying to inform people about the issues and their importance.
That goal is important for scientists because the integrity of science teaching in our public schools
is under serious attack. So far, the courts have mostly come to the rescue, but in the end public opinion
will carry the day. Reasonable people need to know what science is about, especially what an established
scientific theory is and how scientists know when it's right. Nonscientists are vulnerable to
arguments like "Evolution is only a theory" and "What's the harm in teaching alternative theories
as well?"
It seems that most Americans
have religious beliefs that are important to them. For some churches the biblical account of creation
is an allegory. Some other churches that interpret the creation account literally hold that there
is no conflict between the Bible and evolution. I have come to know theologically sophisticated
literal believers who understand that there is no conflict, but I think the majority in my audiences
have been uncomfortable with that assertion. They may have been advised by their religious authorities
that science and religion are separate discourses and that a reasonable person can subscribe to
both,1 but they do not understand how cosmological and biological evolution can fail
to deny their religious beliefs.
I start my talks by observing
that both science and religion have been major contributors to the development of Western civilization
and both play an important role in most people's lives, even the lives of those who participate in
neither. Religion addresses moral and existential issues. Science does not. Science describes
the observable world of experience. In the United States, but not in other Western countries, religion
and science are currently experiencing a political confrontation that threatens to do serious
harm to science and possibly also to damage religion. I am trying to advance a dialog between the
science community and the public by explaining what science is about, how it relates to other subjects,
especially religion, and very importantly what the limitations of science are. An example of such
an explanation is on my website.1 Here I will summarize.
Science is based entirely
on experiment. To illustrate what that means, I raise the possibility that the world was created
three hours ago with all our memories and everything else in place, and I encourage discussion of
that possibility. Science cannot refute it. That leads into the notion that a proposition is not
a scientific theory at all unless it's falsifiable in principle. Absent a possible experiment,
science does not even know the meaning of the proposition. Nobody is surprised when I confess that
I'm really not thinking of three hours ago, but of a few thousand years.
Science and religion have
different assumptions, different rules of inference, and different definitions of truth or reality.
The fence that surrounds science is the test by experiment. That fence is both the greatest strength
and the most fundamental limitation of science, and it needs to be respected from both sides. Scientists
may have opinions about religion, but they cannot honestly invoke the authority of science when
they try to apply the logic of science on the other side of the fence. Similarly, creationists and
advocates of intelligent design should not pretend to be conducting a scientific argument.
What is a theory?
Science, in Albert Einstein's words,
"describes what is." Such a description consists of certain laws of nature, which summarize observed
patterns, and of theories. There are speculative theories that have some limited experimental
success. Such theories mostly die young when they are confronted with additional experiments.
Durable theories proceed from stated assumptions to describe all the phenomena within their purviews,
have broad applicability, and preferably also have strong predictive power. All theories, though,
face the near certainty that some day newly discovered experimental phenomena will negate them.
Nevertheless, a well established theory will continue to apply within the domain of its success
because the experiments on which it is based will never go away.
My explanation of what
a scientific theory is comes as news to most people. In common parlance a theory can be a simple speculation.
Claims of breakthroughs that overthrow all our theories are made every day. To make the concept
of a durable scientific theory concrete, I usually give a very brief outline of the history and applicability
of Isaac Newton's mechanics or of James Clerk Maxwell's electrodynamics, emphasizing their spectacular
successes but giving no details of the theory itself. To illustrate the predictive power of mechanics,
I describe the discovery of the planet Neptune. To illustrate electrodynamics, I mention the discovery
of radio waves and the incorporation of optics into electrodynamics. Then I tell of the complete
failure of those classical theories when applied to phenomena on the atomic scale or phenomena
involving high speeds or strong gravitational forces. We have new theories, typically built on
the old ones, for those phenomena. The new theories agree with the old ones within the domain of success
of the old ones. They must, or we would not have adopted them. And we continue to use the old theories
where they apply because they work and they're much easier to use. I think many, perhaps most, of
my audiences understand for the first time why a powerful theory is something to be respected.
Following that, I turn
to Charles Darwin's theory of evolution, which I describe as being so completely entangled with
Gregor Mendel's theory of genetics that they are really one theory. You don't have to be a biologist
to discuss evolution and genetics because the details don't matter in such a talk. A useful account
for physicists is given by Philip Kitcher.2 The predictive power of Darwin and Mendel
is stunning. Hundreds of Darwin's predicted missing links have been found. The genes Mendel postulated
in 1860 are seen these days with electron microscopes; biologists routinely cut and paste them
and observe the evolution of new genes that enhance fitness to survive. The theory of Darwin and
Mendel has yet to encounter its limitations. Some day it probably will, but it is certainly permanent
within its vast domain of applicability.
'It's only a theory'
I always discuss the words "It's only
a theory" by saying that for practical purposes that's the same as saying "It's only science," and
the price we can pay for such contempt for science is high. Belief in Newton's mechanics within its
domain of validity is not optional, at least not if you design airplanes or bridges. The sad history
of Trofim Lysenko and the calamities he caused illustrates why belief in the right theory, evolution
in that case, is also not optional. Agricultural practices based on Lysenko's theories, which
contradicted Darwin's evolution, contributed to disastrous crop failures in the Soviet Union
in the 1930s and in China in the 1950s.
None of what I am saying
threatens religion. No observational evidence can disprove some subtle supernatural intervention
in cosmological or biological evolution that would leave us with the evidence we see. That possibility
is important to some scientists. It does not interest me, but I cannot argue against it within the
logic of science. K. E. Miller, in his book Finding Darwin's God ,3 dissects
the objections to evolution and genetics. He then reconciles his Catholic religion with science
by invoking the indeterminacy of quantum mechanics.
The current prosperity
in the US derives in large part from 20th-century advances in physics, such as the transistor. In
the 21st century, the driving force may well be biology. The anticipated advances in medicine and
other practical applications of biology will happen, but not necessarily in this country. We can't
afford to degrade biology in our schools.
I have not encountered
overt hostility to my message, possibly because the dedicated opponents were few in the audiences
I have addressed. If challenged by detailed attacks on aspects of biology, I intend to beg off. I'm
a physicist. I plan to let the audience handle it, and simply say that my view has been heard. I expect
that it will come out well.
The relation between science
and religion is a baggage-laden subject. Style is important if you want to have an impact. I try to
be low-key, even sitting rather than standing if that's practical, and trying not always to have
the last word. That goes against our professional culture but it helps. I'm often asked about my
own religious affiliation or preference, a legitimate question in this arena. I respond forthrightly,
including that I have no supernatural beliefs. Then I suggest that we should concentrate on the
message, not on the messenger. That response has always been accepted respectfully.
A majority of the people
who have approached me about what I said or wrote started the conversation by saying they appreciated
my respect for religion. The message to me is that it is essential not only to be respectful, but to
be visibly so. People's previous experience has made them wary of scientists discussing religion.
Readers of PHYSICS TODAY
may find the decisions in some court cases interesting. The drama begun in the Scopes "monkey" trial
has been replayed many times up to the present. Judge John Jones's landmark decision in the recent
Dover Area School Board case gives an exceptionally clear discussion of the church–state
and scientific issues (PHYSICS TODAY, January 2006, page 32). For the opposite point of view, try
Justice Antonin Scalia's dissent in another recent case. These and some other relevant legal decisions
are available on the Web.1
I have to end this essay
with a scold. Whenever I ask nonscientists whether they have ever before heard a mature discussion
of what science is about, what we require of a theory, and how we recognize the right science, I find
that few have. I myself have never been in a classroom, either as student or as teacher, where those
issues were discussed. We were too busy with pulleys and levers or Hamiltonians. We need to do better.
Murray Peshkin
is a theoretical physicist at Argonne National Laboratory.
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