OXFORD UNIVERSITY PRESS, MAY 2016A good explanation—such as the microbial theory of disease, or evolutionary theory—can bring a wondrous sense of understanding. Unfortunately, for a time, so can a bad one—like the medieval miasma (or “foul-cloud”) theory of disease, or supernatural accounts of the creation of species. Does our sense of understanding carry any objective signs that we are right? If not, what accounts for the dramatic success of modern science, a success driven by ever-more powerful and accurate explanatory understanding? This is the question I take up in Wondrous Truths: The Improbable Triumph of Modern Science.

A sense of understanding exercises a visceral grip on us: visceral because explanation itself has a biological backstory. The simple sea slug Aplysia cannot explain, but it can learn. It can learn, through classical conditioning, to retract from a noxious stimulus, and through operant conditioning, to bite more frequently. To...

Objective truth is similarly decoupled from the sensation of insight. Some researchers describe insight as an “aha” moment that can result in new interpretations or solutions. But studies in which subjects are induced to perceive “aha” moments, regardless of whether they are presented with right or wrong answers to puzzles, have shown that people can get a feeling of insight even when they are chronically mistaken. In the real world, scientists seldom know whether the correct solution is contained in their choice set, or even whether their problem has a solution. Tracking the truth is that much harder when you have no clue what it looks like.

For us to achieve genuine insight, truth has to cooperate. Without the subtle perceptual and cognitive arrangements that a good theory supplies, we are like pilots flying without instruments on a dark night. Such pilots can fall prey to a phenomenon called “the false climb.” Acceleration pushes bones in the middle ear toward the back of our head, causing a sensation of upward trajectory. This happens normally when a plane is oriented upward, but it also happens when the plane is accelerating toward the ground. And that is the story of most of the history of science. Steeping oneself in bad theories produces false climbs. Whether apprenticing for years near the furnaces with an adept alchemist or putting in 10,000 hours of study, lab work, and conference preparation as a graduate student and postdoc, you develop a fluency in your thoughts and work that is tightly tied to your cherished theory. There is no certain sign of truth in the sense of understanding.

Evolution has left our perceptual and cognitive powers with informal, even ragged, boundaries. So we arrive at true beliefs and good theories by many means, not all of them experimental. The great biologist J.B.S. Haldane once said that he could not conceive of a physical mechanism of heritability and that “no intelligent person who has thoroughly realized its meaning and implications can continue to hold” such a view. He wasn’t being coy. In 1914, no one had the concept of a physical mechanism that could regulate the development of subtle and complicated biological systems and sustain virtually endless divisions and combinations through successive generations of organisms. But the discovery of DNA was fewer than 40 years away. How did modern biology make this fast transition? Well, the germplasm concept happened to track the actual structure of DNA just closely enough to stimulate accelerating conceptual progress. Once it did, our biological theories firmly oriented our scientific ascent toward the heavens. We have been flying on increasingly accurate instruments ever since. 

J.D. Trout is a professor of philosophy and psychology at Loyola University Chicago. Read an excerpt of  Wondrous Truths.

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