Sean Carroll on the nature of science

Over at Cosmic Variance, Sean Carroll (the physics one) has a nice essay on the nature of a scientific question.  He begins with a discussion of the empirical content of religious beliefs, which some (including journalist Jeremy Manier, who comments on this blog) seem to find unimportant or irrelevant in discussing the compatibility of science and faith:

Some people would prefer to define “religion” so that religious beliefs entail nothing whatsoever about what happens in the world. And that’s fine; definitions are not correct or incorrect, they are simply useful or useless, where usefulness is judged by the clarity of one’s attempts at communication. Personally, I think using “religion” in that way is not very clear. Most Christians would disagree with the claim that Jesus came about because Joseph and Mary had sex and his sperm fertilized her ovum and things proceeded conventionally from there, or that Jesus didn’t really rise from the dead, or that God did not create the universe. The Congregation for the Causes of Saints, whose job it is to judge whether a candidate for canonization has really performed the required number of miracles and so forth, would probably not agree that miracles don’t occur. Francis Collins, recently nominated to direct the NIH, argues that some sort of God hypothesis helps explain the values of the fundamental constants of nature, just like a good Grand Unified Theory would. These views are by no means outliers, even without delving into the more extreme varieties of Biblical literalism.

Carroll then clarifies what he sees as the main endeavor of scientists; the construction of theories:

The definition of theory is also occasionally troublesome, but the humble language shouldn’t obscure the potential reach of the idea: whether we call them theories, models, hypotheses, or what have you, science passes judgment on ideas about how the world works.

And that’s the crucial point. Science doesn’t do a bunch of experiments concerning colliding objects, and say “momentum was conserved in that collision, and in that one, and in that one,” and stop there. It does those experiments, and then it also proposes frameworks for understanding how the world works, and then it compares those theoretical frameworks to that experimental data, and — if the data and theories seem good enough — passes judgment. The judgments are necessarily tentative — one should always be open to the possibility of better theories or surprising new data — but are no less useful for that.

He says this about multiverse (multiple-universe) “theories”, which theistic evolutionists like Kenneth Miller dismiss as “Hail Marys,” desperation passes thrown out by scientists to explain why physical constants appear to be “fine tuned” for the existence of life. Here is what Miller says about multiverses in his book Only a Theory:

Believers . . . are right to remind skeptics and agnostics that one of their favored explanations for the nature of our existence involves an element of the imagination as wild as any tale in a sacred book: namely, the existence of countless parallel simultaneous universes with which we can never communicate and whose existence we cannot even test. Such belief also requires an extraordinary level of “faith” and the nonreligious would do well to admit as much.

In fact, multiverses are not something concocted by scientists to save their cookies; they grow naturally out of some theories of physics.  As Carroll argues:

The same logic applies, for example, to the highly contentious case of the multiverse. The multiverse isn’t, by itself, a theory; it’s a prediction of a certain class of theories. If the idea were simply “Hey, we don’t know what happens outside our observable universe, so maybe all sorts of crazy things happen,” it would be laughably uninteresting. By scientific standards, it would fall woefully short. But the point is that various theoretical attempts to explain phenomena that we directly observe right in front of us — like gravity, and quantum field theory — lead us to predict that our universe should be one of many, and subsequently suggest that we take that situation seriously when we talk about the “naturalness” of various features of our local environment. The point, at the moment, is not whether there really is or is not a multiverse; it’s that the way we think about it and reach conclusions about its plausibility is through exactly the same kind of scientific reasoning we’ve been using for a long time now. Science doesn’t pass judgment on phenomena; it passes judgment on theories.

Carroll then explains why certain religious claims are indeed empirical claims about the real world, and in that sense are scientific:

Now let’s turn to a closely analogous question. There is some historical evidence that, about two thousand years ago in Galilee, a person named Jesus was born to a woman named Mary, and later grew up to be a messianic leader and was eventually crucified by the Romans. (Unruly bloke, by the way — tended to be pretty doctrinaire about the number of paths to salvation, and prone to throwing moneychangers out of temples. Not very “accommodating,” if you will.) The question is: how did Mary get pregnant?

One approach would be to say: we just don’t know. We weren’t there, don’t have any reliable data, etc. Should just be quiet.

The scientific approach is very different. We have two theories. One theory is that Mary was a virgin; she had never had sex before becoming pregnant, or encountered sperm in any way. Her pregnancy was a miraculous event, carried out through the intervention of the Holy Ghost, a spiritual manifestation of a triune God. The other theory is that Mary got pregnant through relatively conventional channels, with the help of (one presumes) her husband. According to this theory, claims to the contrary in early (although not contemporary) literature are, simply, erroneous.

There’s no question that these two theories can be judged scientifically. One is conceptually very simple; all it requires is that some ancient texts be mistaken, which we know happens all the time, even with texts that are considerably less ancient and considerably better corroborated. The other is conceptually horrible; it posits an isolated and unpredictable deviation from otherwise universal rules, and invokes a set of vaguely-defined spiritual categories along the way. By all of the standards that scientists have used for hundreds of years, the answer is clear: the sex-and-lies theory is enormously more compelling than the virgin-birth theory.

Finally, he goes into the methodological naturalism/philosophical naturalism distinction that some people, including Mooney and Kirshenbaum in their book Unscientific America, use as a stick to beat those mean atheists. As Russell Blackford has shown, this distinction is really a red herring in the discussion about whether science and faith are compatible.

Could science, through its strategy of judging hypotheses on the basis of comparison with empirical data, ever move beyond naturalism to conclude that some sort of supernatural influence was a necessary feature of explaining what happens in the world? Sure; why not? If supernatural phenomena really did exist, and really did influence things that happened in the world, science would do its best to figure that out.

It’s a nice piece, and I doubt that anyone could construe it as “militant” or “shrill”. Go read the whole thing.