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Galileo on Critical Thinking and the Folly of Believing Your Preconceptions

“To divine that wonderful arts lie hid behind trivial and childish things is a conception for superhuman talents.”

Galileo Galilei (February 15, 1564–January 8, 1642) was born into a world without clocks, telescopes, or microscopes, where superstition and anthropocentrism moored the human mind in tyrannical dogma — a world that saw itself as the center of the universe. By the end of his lifetime, over the course of which he pioneered modern observational astronomy, invented timekeeping, and even inspired Shakespeare, Galileo’s work had seeded the most significant scientific revolution in human history.

In 1632, nearly two decades after he defended truth in the face of ignorance in his spectacular letter to the Grand Duchess of Tuscany, Galileo penned an impressive book titled Dialogue Concerning the Two Chief World Systems: Ptolemaic and Copernican (public library), which he dedicated to his patron, the Grand Duke of Tuscany. Structured as a series of conversations between a layman and two philosophers, it is at heart a timeless manifesto for critical thinking.

Galileo Galilei (Courtesy of Wellcome Library)

Galileo writes:

To apply oneself to great inventions, starting from the smallest beginnings, is no task for ordinary minds; to divine that wonderful arts lie hid behind trivial and childish things is a conception for superhuman talents.

In the foreword to the modern edition of this intellectual masterwork, Albert Einstein calls it “a mine of information for anyone interested in the cultural history of the Western world and its influence upon economic and political development,” and writes:

A man is here revealed who possesses the passionate will, the intelligence, and the courage to stand up as the representative of rational thinking against the host of those who, relying on the ignorance of the people and the indolence of the teachers in priest’s and scholar’s garb, maintain and defend their positions of authority. His unusual literary gift enables him to address the educated men of his age in such clear and impressive language as to overcome the anthropocentric and mythical thinking of his contemporaries.

Indeed, nearly half a millennium before Carl Sagan crafted his Baloney Detection Kit, Galileo established himself as humanity’s premier nonsense-buster and made it his chief mission to counter ignorance and indolence with critical thinking — something crisply articulated in the words of one of the book’s fictional protagonists:

In the long run my observations have convinced me that some men, reasoning preposterously, first establish some conclusion in their minds which, either because of its being their own or because of their having received it from some person who has their entire confidence, impresses them so deeply that one finds it impossible ever to get it out of their heads. Such arguments in support of their fixed idea as they hit upon themselves or hear set forth by others, no matter how simple and stupid these may be, gain their instant acceptance and applause. On the other hand whatever is brought forward against it, however ingenious and conclusive, they receive with disdain or with hot rage — if indeed it does not make them ill. Beside themselves with passion, some of them would not be backward even about scheming to suppress and silence their adversaries.

Many centuries later, trailblazing physicist and chemist Michael Faraday issued an equally impassioned clarion call for countering our propensity for self-deception — a propensity powered by what modern psychologists have termed “the backfire effect.”

Dialogue Concerning the Two Chief World Systems brims with a wealth more of Galileo’s enduring legacy of critical thinking. Complement it with I, Galileo — a marvelous picture-book about the life of the great scientist — then revisit John Dewey on the art of reflection in the age of instant opinions and Malcolm Gladwell on the importance of changing your mind.

Published October 8, 2015




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