What Skepticism Reveals about Science

A skeptic's journey for truth in science

So many claims of this nature are based on negative evidence. That is, if science cannot explain X, then your explanation for X is necessarily true. Not so. In science, lots of mysteries are left unexplained until further evidence arises, and problems are often left unsolved until another day. I recall a mystery in cosmology in the early 1990s whereby it appeared that there were stars older than the universe itself—the daughter was older than the mother! Thinking that I might have a hot story to write about that would reveal something deeply wrong with current cosmological models, I first queried California Institute of Technology cosmologist Kip S. Thorne, who assured me that the discrepancy was merely a problem in the current estimates of the age of the universe and that it would resolve itself in time with more data and better dating techniques. It did, as so many problems in science eventually do. In the meantime, it is okay to say, “I don’t know,” “I’m not sure” and “Let’s wait and see.”

To be fair, not all claims are subject to laboratory experiments and statistical tests. Many historical and inferential sciences require nuanced analyses of data and a convergence of evidence from multiple lines of inquiry that point to an unmistakable conclusion. Just as detectives employ the convergence of evidence technique to deduce who most likely committed a crime, scientists employ the method to determine the likeliest explanation for a particular phenomenon. Cosmologists reconstruct the history of the universe by integrating data from cosmology, astronomy, astrophysics, spectroscopy, general relativity and quantum mechanics. Geologists reconstruct the history of Earth through a convergence of evidence from geology, geophysics and geochemistry. Archaeologists piece together the history of a civilization from pollen grains, kitchen middens, potshards, tools, works of art, written sources and other site-specific artifacts. Climate scientists prove anthropogenic global warming from the environmental sciences, planetary geology, geophysics, glaciology, meteorology, chemistry, biology, ecology, among other disciplines. Evolutionary biologists uncover the history of life on Earth from geology, paleontology, botany, zoology, biogeography, comparative anatomy and physiology, genetics, and so on.

Once an inferential or historical science is well established through the accumulation of positive evidence, however, it is just as sound as a laboratory or experimental science. For creationists to disprove evolution, for example, they need to unravel all these independent lines of evidence as well as construct a rival theory that can explain them better than the theory of evolution. They have not, instead employing only negative evidence in the form of “if evolutionary biologists cannot present a natural explanation of X, then a supernatural explanation of X must be true.”

The principle of positive evidence applies to all claims. Skeptics are from Missouri, the Show-Me state. Show me a Sasquatch body. Show me the archaeological artifacts from Atlantis. Show me a Ouija board that spells words with securely blindfolded participants. Show me a Nostradamus quatrain that predicted World War II or 9/11 before (not after) the fact (postdictions don’t count in science). Show me the evidence that alternative medicines work better than placebos. Show me an ET or take me to the Mothership. Show me the Intelligent Designer. Show me God. Show me, and I’ll believe.

Most people (scientists included) treat the God question separate from all these other claims. They are right to do so as long as the particular claim in question cannot—even in principle—be examined by science. But what might that include? Most religious claims are testable, such as prayer positively influencing healing. In this case, controlled experiments to date show no difference between prayed-for and not-prayed-for patients. And beyond such controlled research, why does God only seem to heal illnesses that often go away on their own? What would compel me to believe would be something unequivocal, such as if an amputee grew a new limb. Amphibians can do it. Surely an omnipotent deity could do it. Many Iraqi War vets eagerly await divine action.

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