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never will be, anyone around to read the book, or any RNA molecules that
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can read the DNA and go off to make protein— there is no point in talking
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about information.
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From this perspective, the appearance of information- bearing objects in
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the course of the undirected evolution of matter and life is unsurprising. It
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happens because— wait for it— the universe started with an extremely low
02
entropy. That means it was in a very specific kind of state; just knowing the
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low- entropy macroscopic configuration of the universe gives us a tremen-
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dous amount of information about its microscopic state. (In equilibrium,
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where entropy is high, the microstate could be almost anything, and we
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have essentially no information about it.) As the universe evolves from this
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very specific configuration to increasingly generic ones, correlations be-
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tween different parts of the universe develop very naturally. It becomes use-
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ful to say that one part carries information about another part. It’s just one
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of the many helpful ways we have of talking about the world at an emergent,
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macroscopic level.
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In the late 1990s, a controversy arose about a “Statement on Teaching Evo-
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lution” adopted by the National Association of Biology Teachers (NABT)
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in the United States:
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The diversity of life on earth is the result of evolution: an
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unsupervised, impersonal, unpredictable and natural process of
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temporal descent with genetic modification that is affected by
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natural selection, chance, historical contingencies and changing
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environments.
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The controversial bit was the inclusion of the words “unsupervised” and
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“impersonal.” It was thought by some that this characterization went be-
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yond the merely scientific, to pass judgment on questions that belonged to
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the sphere of religion. Two prominent theologians, Alvin Plantinga and
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Huston Smith, wrote a letter to the NABT, arguing that this encroachment
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would backfire by “lower[ing] Americans’ respect for scientists and their
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place in our culture.” The thought was presumably that in any perceived
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conflict between science and religion, Americans will always choose reli-
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gion. Plantinga and Smith urged the board of directors to amend the state-
33
ment to delete “unsupervised” and “impersonal.” After some debate, the
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board agreed, and those words were dropped from the statement in future
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publications.
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One can argue about the political wisdom of such a move, but the
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original wording of the NABT statement was scientifically appropriate.
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The theory of evolution describes an unsupervised and impersonal process.
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The theory might be wrong, or incomplete; what looks like unguided evolu-
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tion to us might be secretly nudged in some preferred direction by a subtle,
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unseen force. But that’s a different theory, one that you are welcome to flesh
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out and try to test using conventional scientific techniques. In the theory
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that seems to provide an excellent description of the history of life on Earth,
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nothing is being supervised, and nothing is personal. Natural selection does
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not strive toward any goal, whether it is increasing amounts of complexity,
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the ultimate appearance of consciousness, or the greater glory of God.
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Given the enormous empirical successes of Darwin’s theory, it is not
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surprising that some religious thinkers have proposed versions of “theistic
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evolution”— seminatural selection, but guided by God’s hand. Supporters
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of this view include a number of distinguished biologists, including Francis
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Collins, director of the US National Institutes of Health, and Kenneth
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Miller, a cell biologist who has actively campaigned against the teaching of
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creationism in American schools.
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Perhaps the most popular way of attempting to reconcile evolution with
18
divine intervention is to take advantage of the probabilistic nature of quan-
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tum mechanics. A classical world, so the reasoning goes, would be perfectly
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deterministic from start to finish, and there would be no way for God to
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influence the evolution of life without straightforwardly violating the laws
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of physics. But quantum mechanics only predicts probabilities. In this view,
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God can simply choose certain quantum- mechanical outcomes to become
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real, without actually violating physical law; he is merely bringing physical
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reality into line with one of the many possibilities inherent in quantum
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dynamics. Along similar lines, Plantinga has suggested that quantum me-
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chanics can help explain a number of cases of divine action, from miracu-
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lous healing to turning water into wine and parting the Red Sea.
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True, all of these seemingly miraculous occurrences would be allowed
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under the rules of quantum mechanics; they would simply be very unlikely.
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Very, extremely, outrageously unlikely. If we populated every planet circling
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every star in the universe with scientists, and let them do experiments con-
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tinuously for many times the current age of the observable universe, it
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would be extraordinarily improbable that even one of them would witness
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a single drop of water changing into wine. But it’s possible.
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“Possible” doesn’t quite do the job that advocates of theistic evolution
02
would like it to do. There are roughly two scenarios. In one, the choices
03
made at each quantum event
have a high probability of coming true on
04
their own, and the hand of God is simply picking one likely event among
05
several possibilities. In that case, God isn’t doing much of anything at all.
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The appearance of human beings was never very improbable; it could easily
07
have happened without any divine intervention. If you pray that a fair coin
08
flip comes up heads, and it does, it would seem strange to attribute too
09
much credit to God. Or, from a Bayesian perspective, the gain in likelihood
10
you achieve through divine intervention isn’t nearly enough to overcome
11
the added complexity and inevitable loss of precision involved in allowing
12
supernatural influences to alter the course of the physical world.
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The other scenario is that the events necessary to bring about human
14
beings through the course of evolution were extremely unlikely, even
15
though they were possible— comparable, perhaps, to the spontaneous part-
16
ing of the Red Sea. In that case, you are not simply taking advantage of
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quantum indeterminacy; you are violating the laws of physics. Observing
18
an event that is so extremely unlikely that you wouldn’t expect to see it
19
anywhere in the observable universe should count as evidence that you are
20
calculating probabilities in the wrong theory. If someone flips a coin
21
one hundred times and gets heads every time, you are observing an out-
22
come that was possible if the coin was fair— but it’s much more likely that
23
the game is rigged.
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Quantum indeterminacy doesn’t offer the slightest bit of cover for those
25
who want to make room for God to influence the evolution of the world. If
26
God micromanages which outcomes are realized in quantum events, it is
27
just as much an intervention as if he were to alter the momentum of a planet
28
in classical mechanics. God either does, or does not, affect what happens in
29
the world.
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The problem for theism is that there’s no evidence that he does. Advo-
31
cates of theistic evolution do not make a positive case that we need divine
32
intervention to explain the course of evolution; they merely offer up quan-
33
tum mechanics as a justification that it could possibly happen. But of course
34
it can possibly happen, if God exists; God can do whatever he wants, no
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matter what the laws of physics may be. What theistic evolutionists are ac-
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tually doing is using quantum indeterminacy as a fig leaf: it’s not that God
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is allowed to act in the world, it’s that they are allowed to imagine him act-
01
ing in a way such that nobody would notice, leaving no fingerprints.
02
It is unclear why God would place such a high value on acting in ways
03
that human beings can’t notice. This approach reduces theism to the case of
04
the angel steering the moon, which we considered in chapter 10. You can’t
05
disprove the theory by any possible experiment, since it is designed precisely
06
to be indistinguishable from ordinary physical evolution. But it doesn’t
07
gain you anything either. It makes the most sense to place our credence in
08
the idea that the divine influences simply aren’t there.
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Are We the Point?
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As impressive as the appearance and evolution of life are, doesn’t it
seem a bit— fragile? If conditions were just a bit different, doesn’t
it seem plausible that life wouldn’t have come about at all?
This concern is sometimes developed into the positive claim that the
18
existence of life is evidence against naturalism. The idea is that conditions—
19
anything from the mass of the electron to the rate of expansion of the early
20
universe— are fine- tuned for life’s existence. If these numbers were just a
21
little bit different, the argument goes, we wouldn’t be here to talk about it.
22
That makes perfect sense under theism, since God would want us to be
23
here, but might be hard to account for under naturalism. In Bayesian lan-
24
guage, the likelihood of life appearing in the universe might be large under
25
theism, and small under naturalism. We can therefore conclude that our
26
very existence is strong evidence in favor of God.
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The fine- tuning argument for God’s existence rubs some people the
28
wrong way. It seems to take everything that science has discovered since
29
Copernicus and turn it on its head. If this logic is right, we actually are
30
the center of the universe, figuratively speaking. We are the reason the uni-
31
verse exists; numbers like the mass of the electron take the values they do
32
because of us, not simply by accident or even because of some hidden physi-
33
cal mechanism. It can come across as more than a little arrogant to contem-
34
plate all of the interacting quantum fields of the Core Theory, or see an
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image of some of the hundreds of billions of galaxies that populate our uni-
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verse, and say to yourself, “I know why it’s like that— so that I could be here.”
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Nevertheless, fine- tuning is probably the most respectable argument in
01
favor of theism. It’s not a clever- sounding bit of a priori
reasoning that al-
02
lows us to demonstrate the existence of some feature of the universe with-
03
out leaving our armchair. The fine- tuning argument plays by the rules of
04
how we come to learn about the world. It takes two theories, naturalism
05
and theism, and then tests them by making predictions and going out and
06
looking at the world to test which prediction comes true. It’s the best argu-
07
ment we have for God’s existence.
08
It’s still not a very good argument. It relies heavily on what statisticians
09
call “old evidence”— we didn’t first formulate predictions of theism and
10
naturalism and then go out and test them; we knew from the start that life
11
exists. There is a selection effect: we can be having this conversation only in
12
possible worlds where we exist, so our existence doesn’t really tell us any-
13
thing new.
14
Still, naturalists need to face fine- tuning head-on. That means under-
15
standing what the universe is predicted to look like under both theism and
16
naturalism, so that we can legitimately compare how our observations af-
17
fect our credences. We’ll see that the existence of life provides, at best, a
18
small boost to the probability that theism is true— while related features of
19
the universe provide an extremely large boost for naturalism.
20
21
•
22
The most important step is to determine the probability that we would
23
measure various experimental outcomes under each theory. Easier said than
24
done, given that there are many specific versions of both theism and natu-
25
ralism. We will do our best, but should keep in mind that there’s a good bit
26
of leeway in our estimates of the likelihoods, and a certain element of judg-
27
ment that will color our final answers.
28
If naturalism is true, what is the probability that the universe would be
29
able to support life? The usual fine- tuning argument is that the probability
30
is very small, because small changes in the numbers that define our world
31
would render life impossible.
32
A famous example of such a number is the energy of space itself: the
33
vacuum energy, or cosmological constant. According to general relativity,
34
empty space can hold an intrinsic amount of energy in every cubic centime-
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ter. Our best current observations indicate that this energy is small, but not
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The Big Picture Page 51