Faith Versus Fact : Why Science and Religion Are Incompatible (9780698195516) (7 page)

But scientists and philosophers now agree that there is no single scientific method. Often you must gather facts before you can even
form
a hypothesis. One example is Darwin's observation, made on his
Beagle
voyage, that oceanic islands—usually volcanic islands that rose above the sea bereft of life—have lots of birds, insects, and plants that are
endemic,
native only to those islands. The diverse species of finches of the Galápagos and the fruit flies of Hawaii are examples. Further, oceanic islands like Hawaii and the Galápagos either have very few species of native reptiles, amphibians, and mammals or lack them completely, yet such creatures are widely distributed on continents and “continental islands” like Great Britain that were once connected to major landmasses. It is these facts that helped Darwin concoct the theory of evolution, for those observations can't be explained by creationism (a creator could have put animals wherever he wanted). Rather, they lead us to conclude that endemic birds, insects, and plants on oceanic islands descended, via evolution, from ancestors that had the ability to migrate to those places. Insects, plant seeds, and birds can colonize distant islands by flying, floating, or being borne by the wind, while this is not possible for mammals, reptiles, and amphibians. Collecting that data and then recognizing a pattern in it was what helped produce the theory of evolution.

And sometimes the “tests” of hypotheses don't involve experiments, but rather observations—often of things that occurred long ago. It's hard to do experiments about cosmology, but we're completely confident in the existence of the Big Bang because we observe things predicted by it, like the expanding universe and the background radiation that is the echo of that event. Historical reconstruction is a perfectly valid way of doing science, so long as we can use observations to test our ideas (this, by the way, makes archaeology and history disciplines that are, in principle, scientific). Creationists often criticize evolution because it can't be seen in “real time”
(although it has been), apparently ignorant of the massive
historical
evidence, including the fossil record, the useless remnants of ancient DNA in our genome, and the biogeographic pattern I described above. If we accept as true only the things we see happen with our own eyes in our own lifetime, we'd have to regard all of human history as dubious.

While scientific theories can make predictions, they can also be tested by what I call “retrodictions”: facts that were previously known but unexplained, and that suddenly make sense when a new theory appears. Einstein's general theory of relativity was able to explain anomalies in the orbit of Mercury that could not be explained by classical Newtonian mechanics. A thick coat of hair, the lanugo, develops in a human fetus at about six months after fertilization but is usually shed before birth. That makes sense only under the theory of evolution: the hair is a vestige of our common ancestry with other primates, who develop the same hair at a similar stage but don't shed it. (A coat of hair is simply not useful for a fetus floating in warm fluid.)

Finally, it's often said that the defining characteristic of science is that it is
quantitative:
it involves numbers, calculations, and measurements. But that too isn't always true. There's not a single equation in Darwin's
On the Origin of Species,
and the whole theory of evolution, though sometimes
tested
quantitatively, can be stated explicitly without any numbers.

As some philosophers have noted, the scientific method boils down to the notion that “anything goes” when you're studying nature—with the proviso that “anything” is limited to combinations of reason, logic, and empirical observation. There are, however, some important features that distinguish science from pseudoscience, from religion, and from what are euphemistically called “other ways of knowing.”

Falsifiability via Experiments or Observations

Although philosophers of science argue about its importance, scientists by and large adhere to the criterion of “falsifiability” as an essential way of finding truth. What this means is that for theory or fact to be seen as correct, there must be ways of showing it to be wrong, and those ways must have been tried and have failed. I've mentioned how the theory of evolution
is in principle falsifiable: there are dozens of ways to show it wrong, but none have done so. When many attempts to disprove a theory fail, and that theory remains the best explanation for the patterns we see in nature (as is evolution), then we consider it true.

A theory that cannot be shown to be wrong, while it may be
pondered
by scientists, cannot be accepted as scientific truth. When I was a child I made my first theory: that when I left my room, all my plush animals would get up and move around. But to account for the fact that I never actually saw them move or change their positions during my absence, I added a proviso: the animals would instantly assume their former positions when I tried to catch them. At the time, that was an unfalsifiable hypothesis (nanny cams didn't exist). That seems silly, but is not too far removed from theories about paranormal phenomena, whose adherents claim—as they often do for ESP or other psychic “powers”—that the presence of observers actually eliminates the phenomenon. Likewise, claims of supernatural phenomena like the efficacy of prayer are rendered unfalsifiable by the assertion that “God will not be tested.” (Of course, if the tests had been successful, then testing God would have been fine!) A more scientific example of untestability is that of string theory, a branch of physics claiming that all fundamental particles can be represented as different oscillations on one-dimensional “strings,” and that the universe may have twenty-six dimensions instead of four. String theory is enormously promising because if it is right it could constitute the elusive “theory of everything” that unifies all known forces and particles. Alas, nobody has thought of a way of testing it. Absent such tests, it stands as a fruitful theory, but because it's not at present falsifiable, it's one that can't be seen as true. In the end, a theory that can't be shown to be wrong can never be shown to be right.

Doubt and Criticality

Any scientist worth her salt will, when getting an interesting result, ask several questions: Are there alternative explanations for what I found? Is there a flaw in my experimental design? Could anything have gone wrong? The reason we do this is not only to make sure that we have a solid result but also to protect our reputation. There's no better incentive for honesty than
the knowledge that you're competing against other scientists in the same area, some often working on the very same problem. If you screw up, you'll be found out very quickly.

That, by the way, gives the lie to the many creationists who claim that we evolutionists conspire to prop up a theory we supposedly know is wrong. They never specify what motivates us to keep promoting something that they consider so obviously false, but creationists often imply that we're committed to using evolution as a way to buttress the atheism of science. (Never mind that many scientists, including evolutionary biologists, are believers, with no vested interest in promoting atheism.) But the main argument against conspiracy theories in science is that anyone who could disprove an important paradigm like the modern theory of evolution would gain immediate renown. Fame accrues to those who, like Einstein and Darwin, overturn the accepted explanations of their day, not to journeymen who simply provide additional evidence for theories that are already widely accepted.

A striking example of the importance of doubt was the finding in 2011 that neutrinos appeared to move faster than the speed of light, discovered by timing their journey over a path from Switzerland to Italy. That observation was remarkable, for it violated everything we know about physics, especially the “law” that nothing can exceed the speed of light. Predictably, the first thing that the physicists (and almost every scientist) thought when hearing this report was simply, “What went wrong?” Although if such an observation were correct it would surely garner a Nobel Prize, one would risk a lifetime of embarrassment to publish it without substantial replication and checking. And, sure enough, immediate checks found that the neutrinos had behaved properly, and their anomalous speed was due simply to a loose cable and a faulty clock.

Replication and Quality Control

Although unique observations (those reported in a single paper) are common in some areas of science, particularly whole-organism biology like evolution and ecology, in most fields, including chemistry, molecular biology, and physics, results are constantly being replicated by other observers. In those areas results become “true” only when they're repeated often enough
to gain credibility. The discovery of the Higgs boson in 2012, for which Peter Higgs and François Englert received a Nobel Prize the next year, was deemed prize-worthy because it was confirmed by two completely independent teams of researchers, each using rigorous statistical analysis.

A sufficiently novel or startling result will immediately inspire doubtful scientists to repeat it, often bent on disproving it. Other scientists, assuming your results are correct, might try to build on them to find new things, and part of that involves verifying your original results. The whole edifice of modern molecular genetics depends on the accuracy of the double-helix model of DNA, its process of replicating by unzipping and using each strand as a template to build another, and on the notion that the genetic code involved triplets of bases, each triplet coding for one unit (amino acid) of a protein. If any of this had been wrong, it would have been discovered very quickly as the field advanced. Likewise, each advance tested by proxy all the preceding ones.

Science has additional features that keep us from fooling ourselves by conscious or unconscious finagling with experiments or data. These include statistical analyses that tell us how likely our results might have been due to chance alone rather than to our new theory; blind testing, in which the researcher is prevented from knowing what material she's testing (“double-blind studies,” in which neither researcher nor patient knows the identity of the treatment being given, are the gold standard for drug testing); and data sharing, which requires scientists to provide their raw data to anyone who asks, ensuring that those who want to can search for anomalies and run their own statistical tests.

Parsimony

Scientific theories invoke no more factors than necessary to adequately explain any phenomenon. This, like everything in the toolkit of science, is not an a priori
requirement of the scientific method, but simply a method developed over centuries of experience. In this case, ignoring things that seem irrelevant keeps us from distracting ourselves with false leads. If we can completely explain the presence of smallpox by infection with a virus, why even
consider
factors like whether the patient ate too much sugar, or, indeed, whether, as was once thought, he was being divinely punished for immorality?

One unparsimonious method is invoking gods. Our experience that supernatural hypotheses have never advanced our understanding of the cosmos has, as we'll see later, led to the idea of
philosophical naturalism:
the notion that supernatural entities not only fail to help us understand nature, but don't seem to exist at all.

Living with Uncertainty

One of the most common statements we hear in science is “I don't know.” Scientific papers, even those that report fairly solid findings, are hedged with statements like “this suggests that . . . ,” or “if this finding is correct . . . ,” or “this result should be verified by further experiments.” Granted, scientists are people, and we'd like to know all the answers, but in the end it's our ignorance that moves science forward. It's no shame to admit it, for without the unknown, there would be no science, nothing to spark our curiosity. But that attitude assumes that there are some answers we might
never
know.

One of these is how life originated. We know it happened between 4.5 billion years ago, when the Earth was formed, and 3.5 billion years ago, when we already see the first bacterial fossils. And we're virtually certain that all living creatures descended from one original life-form, for virtually all species share the same DNA code, something that would be a remarkable coincidence if the code arose several times independently. But because the first self-replicating organism was small and soft-bodied and thus could not fossilize (it was likely a molecule, perhaps one surrounded by a cell-like membrane), we don't have a way of recovering it.

Now, we may be able to create life in the laboratory under conditions thought to prevail on the early Earth—I predict we'll do this within fifty years—but that tells us only that it
could
happen, not how it
did
happen. Like historians lacking data on crucial events (was there a real Homer who wrote the
Iliad
and the
Odyssey
?), students of historical sciences like cosmology and evolutionary biology are often forced to live with uncertainty. (The uncertainty is not about
everything,
however: we know when both the universe and life on Earth began; we're just not sure how.) Living with uncertainty is hard for many people, and is one of the reasons why people prefer religious truths that are presented as absolute. But many scientists (I am one) share
the feelings of Richard Feynman, who expressed his comfort with ignorance in an interview with the BBC:

I can live with doubt
, and uncertainty, and not knowing. I think it's much more interesting to live not knowing than to have answers which might be wrong. I have approximate answers and possible beliefs and different degrees of certainty about different things. But I'm not absolutely sure of anything, and there are many things I don't know anything about, such as whether it means anything to ask why we're here, and what the question might mean. I might think about it a little bit; if I can't figure it out, then I go on to something else. But I don't have to know an answer. I don't feel frightened by not knowing things, by being lost in the mysterious universe without having any purpose, which is the way it really is, as far as I can tell—possibly. It doesn't frighten me.