Reassessing the Scientific Method

Objective rules for weighing scientific evidence are impossible.

Posted Nov 17, 2020

This post is a review of The Knowledge Machine: How Irrationality Created Modern Science by Michael Strevens.

Most of us believe the "Scientific Method" plays a pivotal role in unlocking the mysteries of the universe. Celebrated as an objective, self-correcting way of acquiring knowledge, the method involves careful observation of phenomena; the development of a hypothesis about them; the design and implementation of experiments to test deductions drawn from each hypothesis; and publication of data that makes it possible for other researchers to verify, build on, or falsify the findings.  

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In The Knowledge Machine, Michael Strevens, a professor of philosophy at New York University and the author, among other books, of Depth: An Account of Scientific Experimentation and Thinking on Your Feet: How Empirical Psychology Vindicates Armchair Philosophy, reassesses the Scientific Method. And along the way, he provides engaging and immensely informative portraits of iconic scientists, including Francis Bacon, Rene Descartes, Isaac Newton, Charles Darwin, Albert Einstein, and Murray Gell-Mann, a host of their less well-known contemporaries, and William Whewell, Karl Popper, and Thomas Kuhn, the great philosophers of science.

Breathtakingly bold and brilliant, sophisticated and searching, The Knowledge Machine is destined to become a classic account of the origins and structure of scientific inquiry.

Strevens demonstrates that an objective rule for weighing scientific evidence is impossible. Science, he writes, is driven by arguments “between people who have made up their minds and want to convert or at least confute their rivals. Opinion that runs hot-blooded ahead of established fact is the life force of scientific inquiry.” And scientists’ conclusions always rely on “auxiliary assumptions” about, for example, the functioning and calibration of measuring instruments (like the Brazilian astrographic telescope used by Arthur Eddington to “prove” that Einstein’s gravitational theory was more accurate than Newton’s) and the difficulty or impossibility of repeating observations and experiments. Auxiliary assumptions, about which opinions often differ widely, Strevens writes, are like “links in a chain leading from theory to evidence.”

To identify the essence of the Scientific Method, Strevens lays out a methodological precept he calls “the iron law of explanation.” Science’s “first commandment,” the iron law consists of a procedural agreement among scientists (entered into, consciously and unconsciously, amidst the wars between Catholics and Protestants in the 17th century) to confine their “attention to the production of exquisitely detailed empirical facts” and (in a manner that seems tolerant, prudent, and even civilized) away from unverifiable aesthetic, theological, psychological, or philosophical arguments. 

Allowing no attempt to interpret the evidence in their official publications, this protocol does not so much resolve disputes as prolong them: After all, scientists can always identify another experiment to conduct. It channels “hope, anger, envy, ambition, resentment—all the fires fuming in the human heart—to one end: the production of empirical evidence.” The iron law provides a “special kind of objectivity," resulting from a consensus (a “Baconian convergence”) that  emerges “from the tissue of uncertainty and dissent,” forming what Kuhn called a “paradigm,” that can be imposed on the scientific debate “without being upended by the essential subjectivity of scientific reasoning.” And it sets rules of the game that are fixed for all time.

Adopted by scientists (most importantly, Newton, a mathematical physicist, alchemist, and biblical exegete) seeking to free themselves from the religious wars of the 17th century by compartmentalizing, the iron law, Strevens reminds us, has given us vaccines, air conditioners, electric motors, computers, and other filaments of connectivity. That said, he admonishes scientific “holy men chanting empiricist incantations” and suggests that there is “good empirical evidence for the efficacy of non-empirical reasoning”—theoretical elegance, beauty, or symmetry—in scientific inquiry. Strevens points to a few eminent scientists—Einstein and E. O. Wilson among them—who “conform to the iron rule in their technical writing” but are not its captives.  

He concludes, however, that clamps remain the norm—and that the knowledge machine, which is so effective in making so many lives so much better, “is not a high expression of what is humanly good.”