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History is full of brilliant people who believed ridiculous things. Isaac Newton devoted years to searching for the philosopher’s stone. Thomas Edison promoted radioactive products as health remedies. Steve Jobs believed that his vegan diet made regular bathing unnecessary.
The problem isn’t that intelligent people cannot think. It’s that they’re human.
We like to imagine that reason is an impartial judge, carefully weighing evidence before arriving at a verdict. More often, it behaves like a defence lawyer, marshalling arguments for conclusions we reached for entirely different reasons.
Our hopes, fears, loyalties, ambitions, and prejudices all shape the way we reason. We are naturally drawn to arguments that flatter our opinions, excuse our behaviour, or confirm our suspicions. And the more intelligent we are, the more ingenious our rationalizations can become.
The ancient Greeks understood this all too well.
Persuasion Versus Truth
In democratic Athens, success increasingly depended on persuasion. Citizens defended themselves in the law courts, debated policy in the Assembly, and competed for influence with words rather than swords. A new class of professional teachers, known as the Sophists, arose to teach this art of argument.
Their lessons were practical rather than philosophical. They taught their students—often young, wealthy aristocrats—how to sway an audience, defend either side of a case, and even make the weaker argument appear the stronger.
For Plato, this represented a profound problem. His beloved teacher, Socrates, had been condemned to death by a jury persuaded more by rhetoric than by reason. If eloquence—or simple pandering—could triumph over truth, what hope was there for philosophy?
Plato’s pupil Aristotle responded by laying the foundations of logic and identifying the many ways in which arguments can go wrong. If rhetoric explains how people are persuaded, logic lays out when they ought to be.
Yet beneath this history lies an uncomfortable lesson.
Bad arguments rarely persuade us because they are logically compelling. They persuade us because they satisfy some psychological need.
An ad hominem attack invites us to judge the speaker rather than the argument. A straw man offers an easier opponent to defeat. An appeal to popularity reassures us that millions of other people cannot be wrong. A false dilemma offers clarity where reality is usually more complicated. Circular reasoning allows us to begin with the conclusion we wanted all along.
Each exploits a different human weakness. Together, they encourage us to condemn our opponents, sidestep the real issue, follow the crowd, crave certainty, and believe what we wanted to believe all along.
Why We Fall for Bad Arguments
Plato feared that rhetoric had become detached from truth, while Aristotle sought to distinguish valid reasoning from mere persuasion. But neither believed that bad arguments prevailed simply because people lacked intelligence. They prevailed because they appealed to pride, fear, tribal loyalties, wishful thinking, and our deep desire to be right.
That is why exposing a fallacy so seldom changes anyone’s mind. We do not cling to bad arguments because we are in need of illumination. We cling to them because they satisfy needs that logic alone serves to undermine.
The Sophists discovered that winning an argument is not the same as finding the truth. Plato and Aristotle devoted much of their philosophy to closing the gap between the two. More than two thousand years later, that remains one of our most important tasks—and one at which we keep on backsliding.
History is still full of brilliant people who believe ridiculous things—not because they cannot think, but because they are human.
A version of this post also appears on the author’s website.
