Case file
Semmelweis Reflex
- Filed under
- Too Much Information
The charge
We reflexively reject new evidence because it conflicts with established beliefs, norms, or identity. Novel facts can get dismissed before they are fairly examined.
How it operates
Belief systems provide coherence and status, so disconfirming evidence feels threatening. That threat triggers defensive dismissal rather than careful updating.
Logged incidents
- Incident 01
A company ignores surprising user research because it clashes with the founder's mental model of the customer.
- Incident 02
A medical team dismisses a better protocol because that is not how we do it here.
- Incident 03
An enterprise sales org rejects product-led evidence because it threatens existing power structures.
What to watch for
Ask yourself: 'Am I rejecting this because the evidence is weak, or because it threatens a familiar model or status order?'
Recommended action
Use consider-the-opposite, pilot tests, and independent replication before dismissing anomalies. A red-team review can surface whether resistance is evidence-based or identity-based.
Known associates
- Confirmation BiasWe seek, interpret, and remember information in ways that support what we already believe.
- Congruence BiasWe test whether our favored idea fits instead of trying to find out whether it fails.
- Choice-Supportive BiasWe remember the option we chose as better than it really was and the options we rejected as worse than they…
- Selective PerceptionPeople perceive the same evidence differently because expectations, motives, and prior beliefs shape what…
- Observer-Expectancy EffectAn observer's expectations can subtly change what they notice, record, or even elicit from others.
- Ostrich EffectWe avoid information that might be painful, threatening, or shame-inducing, especially when it could force…
Source of record