Belief and Reasoning Biases

Semmelweis reflex

Rejecting new evidence because it challenges established norms.

What Is Semmelweis reflex?

Semmelweis reflex is a thinking trap where rejecting new evidence because it challenges established norms.

How It Tricks You

It can make a conclusion feel proven because it fits what already seems true.

Real-World Example

A new safety idea is rejected because it challenges standard practice.

Seen Online As

• The fast interpretation is doing more work than the evidence.
• The claim feels obvious before the check question is asked.
• A shortcut is making the judgment feel more certain than it is.

What To Ask Instead

Am I rejecting this because it is wrong or unfamiliar?

Related Thinking Traps

• Anchoring bias
• Confirmation bias
• Framing effect
• Loss aversion

Common Situations

• Thinking Traps at Work
• Thinking Traps in Politics
• Thinking Traps Online

Quick FAQ

What is Semmelweis reflex?

Rejecting new evidence because it challenges established norms.

What is an example of Semmelweis reflex?

A new safety idea is rejected because it challenges standard practice.

How do I spot Semmelweis reflex?

Am I rejecting this because it is wrong or unfamiliar?