Free Faith Versus Fact : Why Science and Religion Are Incompatible (9780698195516) by Jerry A. Coyne

knowledge is not certainty but evidence.”
    And that evidence can change. It’s easy to find cases of accepted scientific “truths” that were later shown to be false. I’ve mentioned a few above, and there are many more. Early cases in the history of science are geocentrism (the Earth as the center of the cosmos) and the Greek concept of the “four humors”: that both personality and disease resulted from the balance of four bodily fluids (black bile, yellow bile, phlegm, and blood). A famous modern case is the demonstration of “N rays,” a form of radiation described in 1903, observed by many people, and then found to be bogus, a result of confirmation bias. Atoms were once considered indivisible particles of matter. There’s even one case of a Nobel Prize awarded for a bogus discovery, that of the
Spiroptera carcinoma,
a parasitic nematode worm that supposedly caused cancer. Its discovery earned Johannes Fibiger the Nobel Prize in Physiology or Medicine in 1926. Soon thereafter, researchers showed that this result was wrong: the worm was simply an irritant that, like many other factors, induced tumors in already damaged cells. But Fibiger’s prize stands, for his discovery seemed true at the time.
    The overturning of some scientific truths has often served as ammunition for religious critics who indict the field for its inconstancy. Science can be
wrong
!
But that mischaracterizes
any
attempt to understand truth, both religious and scientific. Scientific tools and ways of thinking change: how can our understanding of nature not change as well? And, of course, the criticism of inconstancy can be turned right back on religion. There is simply no way that
any
faith can prove beyond question that its claims are true while those of other faiths are false.
    It is a common saying among scientists that we can prove theories wrong (it would be relatively easy to show, for instance, that the formula for water isn’t H 2 O), but that we can never prove them
right,
for new observations couldalways come along that would overturn received knowledge. The theory of evolution, for instance, is regarded by all rational scientists as true, as it’s supported by mountains of evidence from many different fields. Yet there are observations that could, if they surfaced, conceivably disprove that theory. These include, for instance, finding fossils embedded in strata from the “wrong” time, like discovering mammalian fossils in four-hundred-million-year-old sediments, or observing adaptations in one species that are useful only for another species, such as a pouch on a wallaby that can hold only baby koalas. Needless to say, such evidence hasn’t appeared. Evolution, then, is a fact in the scientific sense, something Steve Gould defined as an observation “ confirmed to such a degree that it would be perverse to withhold provisional assent.” Indeed, the only real “proofs” beyond revision are those found in mathematics and logic.
    But some people take this too far , claiming that scientific truths not only are provisional, but change
most of the time
. Science, the argument goes, isn’t really
that
good at apprehending truth, and we should be wary of it. Such claims of inconstancy usually involve medical studies—like the value of a daily aspirin in preventing heart disease, or the advisability of annual mammograms—whose conclusions go back and forth when different populations are sampled. What’s important to remember is that most scientific findings become truths when they’re replicated many times, either directly by other dubious scientists or when repeated as a foundation for further work.
    In reality, we can consider many scientific truths to be about as absolute as truths can be, ones that are very unlikely to change. I would bet my life savings that the DNA in my cells forms a double helix, that a normal water molecule has two hydrogen