“The fatal tendency of mankind to leave off thinking about a thing when it is no longer doubtful, is the cause of half their errors.”
This powerful warning comes from John Stuart Mill, a towering figure in 19th-century philosophy. His words cut through time, exposing a fundamental human flaw. We often crave certainty. Once we find it, we tend to stop questioning. However, Mill argues this intellectual comfort is a trap. He suggests that our biggest mistakes come not from what we don’t know, but from what we think we know for sure. This tendency to accept settled ideas without scrutiny is a dangerous habit. It closes our minds to new perspectives and leads to profound errors in judgment.
This quote challenges us to embrace a state of constant inquiry. It pushes us to see doubt not as a weakness, but as a vital tool for growth and understanding. Ultimately, Mill’s insight is a call to intellectual humility and lifelong learning.
The Source and Context: A Look at On Liberty
John Stuart Mill penned this famous line in his seminal 1859 work, On Liberty. Source . This book is a passionate defense of individual freedom against the pressures of the state and societal opinion. Mill feared the