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Darwinism: Science or Philosophy
Chapter 8a
Response to Frederick Grinnell
Peter van Inwagen
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This paper is a response to a presented paper.
THE BODY OF PROFESSOR GRINNELL's paper seems to me to be an argument for what I
would call methodological naturalism. This I take to be the thesis that
scientific explanations and theories should assert or presuppose the existence of
nothing but natural objects. Scientific explanations, moreover, should not assert
or presuppose that these natural objects have any properties but natural
properties. (Some might say that a natural object like Mt. Everest has such
properties as being sublime or being a divine creation, and that, unlike height
and weight and other measurable qualities of things, these are not natural
properties.) It may be, says the methodological naturalist, that there are
objects that are not natural objects; and it may be that some natural objects
have properties that are not natural properties. But such things and such
properties are, if they exist, irrelevant to the enterprise of science.
Many questions might be asked about methodological naturalism. One of the most
important is: What does "natural" mean? But I will simply assume that we
understand this term well enough to go on.
I know, have corresponded with, and have read books by many scientists who are
Christians. Every one of them is a methodological naturalist. All of them, of
course, believe that there are things that are not natural things, and all of
them believe that even natural things have properties that are not natural
properties. Nevertheless, they would not dream of asserting or presupposing the
existence of anything but natural objects and natural properties in their
theories and explanations.
Methodological naturalism is, therefore, old news, and Professor Grinnell's paper
is largely an argument for the truth of this piece of old news. But there is
nothing wrong with that. His paper is a philosophical paper, and one of the main
tasks of philosophy is to argue for old news. There are a lot of good reasons for
this: arguments for old news help us better to understand our beliefs. For
example, and they remind us of the value of and centrality to our thought of
various beliefs that we might otherwise be as unaware of as a fish is of
water.
Is the argument a good one? Well, I have heard this sort of argument before, and
I have no quarrel with it. But it does strike me that there are some other things
that might be said in defense of methodological naturalism.
In my own contribution to this symposium I mention a well-known episode in the
history of science, the story of Newton and the instability of the solar system.
I want to contrast this story with another story of more recent vintage. Several
years ago, a few physicists suggested that certain effects could be explained
only by the postulation of a fifth fundamental force (in addition to gravity,
electromagnetism, the weak nuclear force, and the strong nuclear force). They
labeled this force "hypergravity." After a short while, however, general
agreement was reached that the effects the force was supposed to explain did not
in fact exist, and hypergravity was removed to the scientific attic, to gather
dust beside phlogiston and the luminiferous ether.
Now suppose that someone were to reason as follows. "Newton and the proponents of
hypergravity each attempted to explain a certain effect by postulating something
invisible to account for it-in the one case, God, and in the other, hypergravity.
In each case it turned out that no account was needed, and the effort was
dropped. But what is the difference between the two cases? If the postulation of
a force called hypergravity (which is detectable only through the effects it is
postulated to explain) is something that one can do without violating the canons
of science, why is the postulation of a being called God (who is likewise
detectable only through the effects he is postulated to explain) not something
that one can do without violating the canons of science? What is the essential
difference between the two cases? Why not, in fact, reject methodological
naturalism as foundational to science, and say that scientific explanations
involving God would be perfectly all right in principle-it just turns out that
(as Laplace observed) they are not needed? (Not so far, at any rate. But we
should recognize no fundamental objection to introducing them in the future if
they should turn out to be needed.)"
I think that this reasoning is misguided, and I am not sure that an appeal to
"radical intersubjectivity" does a very good job of explaining why it is
misguided. To explain why it is misguided, I appeal to the following
considerations.
Newton did not have a theory about God and his relation to the solar system that
explained why or when or how God would correct the orbits of the planets. At any
rate, he did not have a theory that explained these things in the sense that his
theories of motion and gravitation explained Kepler's laws of planetary motion.
According to Newton, correcting the orbits of the planets is something God "just
does," and there is really nothing more to be said about the matter. The
advocates of hypergravity, on the other hand, did not simply say, "There's a
thing, a natural force, called 'hypergravity' and it is the cause of phenomenon
X." Rather, they had a theory with a detailed mathematical structure, on the
basis of which one could predict the occurrence (under conditions whose
occurrence in conjunction with phenomenon X could be verified) of phenomenon X.
If they had said, "There's a thing, a natural force, called
'hypergravity' and it is the cause of phenomenon X," and had said no more than
this, then they would not have provided a scientific explanation of "phenomenon
X," despite the fact that their statement appealed only to purely natural objects
and properties.
The trouble with trying to construct scientific theories that appeal to God or to
other supernatural agencies is, I suggest, that the "theories" always turn out
not neatly to be theories at all. They turn out to be simple assertions, usually
to the effect that some causal relation holds between God and some part of the
natural world. I myself think that the statement "God is the creator of the
cosmos" is true. And I think that it is a far more important truth than anything
discovered by Newton, Darwin, or Einstein. But I do not mistake it for a
scientific theory. It is not a scientific theory because it is not a theory of
any sort. Theories tell you how things work, and this statement tells you what
happened.
If the statement "God is the creator of the cosmos" is not a scientific theory,
neither is the statement "Because God created it" a scientific explanation of the
existence of the cosmos. It is an explanation all right, but it is not a
scientific explanation. Scientific explanations appeal to
theories. They are applications of theories to particular events or types of
event or phenomena. The statement "Because God created it" is no more a
scientific explanation of the existence of the cosmos than "Because Booth shot
him" is a scientific explanation of the death of Lincoln: in neither case is a
theory involved.
Thus I would supplement Professor Grinnell's argument for methodological
naturalism.
It is a commonplace in discussions like this to distinguish methodological from
ontological or metaphysical naturalism. Ontological or
metaphysical naturalism is the thesis that everything that exists is a
natural object having only natural properties. (Whatever "natural" means;
remember that I have not undertaken to define this term.)
It is obvious that metaphysical naturalism entails methodological naturalism, in
the sense that anyone who accepts the former is committed to the latter-one does
not construct theories or explanations that appeal to things that one firmly
believes not to exist. (This statement probably requires some qualification. I
remember a course in colloid chemistry from my undergraduate days in which the
instructor thought it permissible to appeal to "vibrations of the ether
particles" in deriving some of the optical properties of colloids; this appeal
was excused on the ground that the "ether particles" were, in this context, a
"useful fiction.") But what are the implications of methodological naturalism for
metaphysical naturalism?
I know from experience that there are people who simply conflate
methodological and metaphysical naturalism. In a sense, these people might
be said to believe that methodological naturalism entails metaphysical
naturalism. But what these people are really doing is calling both theories by
one name-probably "naturalism"-and are treating "naturalism" as methodological
naturalism when they are called on to defend it, and as metaphysical naturalism
when they are drawing conclusions from it.
Among people who are clear about the distinction between methodological and
metaphysical naturalism, however, it would be hard to find anyone who thought
that methodological naturalism entailed metaphysical naturalism. Almost
everyone who is clear about the distinction between them would agree that someone
could accept methodological naturalism and reject metaphysical naturalism without
any logical inconsistency.
Let me offer an analogy that will help to explain why it is hard to see any
logical connection between methodological and metaphysical or ontological
naturalism. Professor Grinnell tells the story of a man who is looking for his
keys in the light of a street lamp, even though he does not know that that is
where they are. In most versions of the story, the man is a drunk, and knows
that the keys are not in the area lighted by the lamp. That is funny.
Professor Grinnell's story is not funny, however, not really, since the hero of
his story is simply following the very sensible policy of not trying to use his
eyes in the dark; the keys may be in the lighted area, and that is the
only place he has any hope of finding them, so that is where he is looking. He
is, one might say, an adherent of methodological claviluminism. But he
does not accept (nor, of course, does he reject) the thesis of ontological
claviluminism-the thesis that the keys are in fact somewhere in the
lighted area. It is obvious that the adherent of methodological claviluminism is
not logically committed to the thesis of ontological claviluminism. It should be
equally obvious that the adherent of methodological naturalism is not logically
committed to the thesis of ontological (metaphysical) naturalism.
Logical entailment and logical commitment are not everything, however. Some have
suggested that the great and impressive mass of scientific information,
explanation, and theory that are the fruit of the adherence of scientists to
methodological naturalism constitutes important support for metaphysical
naturalism. It has been argued that the fact that a science based on
methodological naturalism has been so successful implies that the world is
without "gaps" that need to be filled in by the acts of a deity: the success of a
science based on methodological naturalism shows that "there is nothing left for
God to do."
In my view, that argument is not cogent. In my view, it appeals to a
theologically very primitive notion of what it is that God is supposed to "do."
But I don't wish in these remarks to address the questions that this sort of
argument raises. I will remark only that it is a philosophical argument, and that
it is by that very fact highly controversial. As with any other philosophical
argument, you accept it or you don't, and it is probably not going to convince
anyone who is not initially sympathetic with its conclusion.
I am not sure what Professor Grinnell thinks about the relation between
methodological and metaphysical naturalism. I don't see any unequivocal evidence
in his paper that he thinks that his arguments (which I read as arguments for
methodological naturalism) offer any support for metaphysical naturalism. There
are, however, a few things that he says that make me a bit uneasy. Perhaps I have
misunderstood him. I'll quote just one sentence.
The key question remained: is life a biochemical event,
or the work of a creative intelligence?
The answer I would give to this "key question" is Yes. That is, I think
that life is both a biochemical event and the work of a creative intelligence.
And I don't see any shadow of inconsistency or tension between these two
features that I ascribe to life. I am just puzzled. I would like to know more
about what lies behind the very exclusive-sounding or in the sentence I
have quoted.
In closing, I would like to make a few comments about what Professor Grinnell
says about religion. The following quotation seems to sum up his ideas.
"Religious faith orients a person toward the ultimate meaning of the world."
Well, yes, I can agree with that. But I think that such a statement could be very
misleading. It could be taken to mean that religious faith is primarily expressed
in musing on the question "What does it all mean?" or at least in some type of
philosophical reflection. It suggests that religious faith consists in some sort
of reaching out by the individual or the community toward a passive infinite.
My faith holds that an active Infinite is reaching out toward me and every other
human being. My faith holds that there is a living reality that is an active
person, beside which the created world (which includes at least the totality
of the distribution of matter and radiation in spacetime) is, in the words of St.
Anselm, "almost nothing." This active, personal, living reality has plans
for me and for you and for everyone else, and is working to bring these
plans to fruition. My faith is (so I believe) a piece of news about these plans,
and it is designed (not by me; I am a mere recipient of this faith) to put me and
anyone who accepts it into right relation to these plans and to their Author.
Let me sharpen these remarks about an "active Infinite' by constructing my own
example of a "religious statement" about the sun. There is nothing particularly
original about it; the thought behind it, if not the exact words I use, is a
thought that any reasonably reflective theist would assent to. It seems to me
better to reflect the religious attitude (or the theistic attitude; I am not
convinced that there is any such thing as "the religious attitude," an attitude
toward things that is supposedly common to, for example, Zen Buddhists and Sunni
Muslims) than Joshua 10:12. That passage is a report of a speech made in the
course of a narrative of Joshua's military adventures. The speech it records is
not science, philosophy, or theology; it is what a novelist would call dialogue.
If you wanted to compare it with something that was supposed to have come from
the tongue or pen of a scientist, the famous words that Galileo never spoke about
the earth (E pur si muove) would be a closer parallel than the words in
Professor Grinnell's paper that Copernicus never wrote about the sun.{1}
But I digress. Here is my "religious Statement about the sun":
The sun exists at God's pleasure. It reflects his glory
as surely as the moon reflects its light, and for that reason it is
in many cultures a symbol of the divine. It exists from moment to
moment only because its continued existence is his will, and it would
instantly cease to exist if he stopped holding it in existence. In
its interior, the principles of general relativity, quantum chromo-
dynamics, and quantum electroweak-dynamics combine to produce the
photons that, aeons after their production. will fall on the surface
of the earth to provide the energy that living organisms will
exploit. These physical laws are inventions of his, chosen freely by
him, from among an unimaginable number of alternative possible seas
of laws. These laws hold from moment to moment only because their
continued holding is his will, and if he were to stop willing that
they hold, the sun and the rest of the physical universe would
instantly dissolve into chaos.
NOTE
{1} At least I don't see how he could have
written them. Professor Grinnell gives no citation, and the words he attributes
to Copernicus seem clearly to misrepresent Copernicus' system. His planets (since
they are embedded in rotating spheres) have to move in perfectly circular orbits.
At the geometrical center of each planetary orbit is a point in empty space, from
which the sun (which Copernicus hardly mentions) is removed by as much as several
solar diameters. The orbits of the planets, as we now know, are slightly
elliptical, with their foci near the center of the sun; in consequence, a system
that made the planets move in perfectly circular orbits around the sun would make
wrong predictions, and they would be wrong enough to have been definitely
inconsistent with sixteenth-century observational data.
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