---
title: "Meaning & Key Takeaway of: The fatal tendency of mankind to leave…"
description: "\"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.\" — John Stuart Mill"
image: "https://sms4smile.com/quotes/i/d28/john-stuart-mill-477_about_the-fatal-tendency-of-mankind-to-leave-o_2051635.png"
---

#  The fatal tendency of mankind to leave off thinking about…

![“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.” quote by John Stuart Mill](https://sms4smile.com/quotes/i/d28/john-stuart-mill-477_about_the-fatal-tendency-of-mankind-to-leave-o_2051635.png)   [Download](https://sms4smile.com/quotes/i/d28/john-stuart-mill-477_about_the-fatal-tendency-of-mankind-to-leave-o_2051635.png) [Open image](https://sms4smile.com/quotes/i/d28/john-stuart-mill-477_about_the-fatal-tendency-of-mankind-to-leave-o_2051635.png)

> “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.”

[John Stuart Mill](https://sms4smile.com/quotes/author/john-stuart-mill/)

## About This Quote

This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation.

When doubts fade, people stop thinking critically about a subject, leading to many mistakes due to unexamined assumptions.

**In simple terms:** Stop questioning when sure, causing errors.

Key Takeaway

Keep questioning even when confident.

Themes

critical thinking doubt error human nature

Mood

reflective cautious

Type

philosophical advice

When to use this quote

- problem solving
- policy making
- scientific research

Key Concepts

cognitive bias intellectual humility decision making

Questions to Reflect On

- How do you guard against complacency?
- When was your last doubt useful?

A Different Perspective

Overconfidence can blind us to new evidence.

★ ★ ★ ★ ★   No ratings yet

[Individuality](https://sms4smile.com/quotes/about/individuality/) [Mankind](https://sms4smile.com/quotes/about/mankind/) [Nonconformity](https://sms4smile.com/quotes/about/nonconformity/) [Thinking](https://sms4smile.com/quotes/about/thinking/)

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