This is a great example of the false cause logical fallacy—because for over 4,000 years, bloodletting was widely accepted as a cure for illness. Imagine the shock professional doctors must have felt when, in the 1830s, studies showed that bloodletting didn’t help—it actually harmed patients.
Bloodletting was popular because some patients seemed to get better afterward. But that improvement had nothing to do with blood loss. This was just a false cause fallacy in action: the doctors assumed the treatment caused recovery, but it was really the body healing itself.
Science is a process, not a set of fixed facts. Even after discovering that bloodletting didn’t work, it took decades to persuade doctors, and many clung to the old ways. Change didn’t fully take hold until a new generation of doctors could “hear” the truth and accept evidence over tradition.
So, how do we know bloodletting doesn’t work? We proved it through observation and experimentation—key to avoiding false cause fallacies.