What is the omission bias?

It is judging harm caused by action as worse than equal harm caused by inaction. We feel more responsible for damage we actively cause than for the same damage we passively allow.

What is an example of the omission bias?

Many people would refuse a vaccine with a small risk of harm while accepting a larger risk from the disease itself — because harm from acting feels worse than the greater harm from doing nothing.

What is the difference between omission bias and action bias?

They pull opposite ways. The omission bias favours inaction (doing nothing feels safer and less blameworthy); the action bias favours doing something even when inaction is better. Which dominates depends on context.

Omission bias

Decision-making

The omission bias is the tendency to judge harmful actions as worse than equally harmful inactions. We feel more responsible for damage we cause by doing something than for the same damage we allow by doing nothing.

Why it happens

Action feels more causal and more intentional than inaction, so it carries more blame and regret — even when the outcome is identical or worse. Doing nothing also feels like the "default," which lets us disown responsibility for what follows from our passivity.

Examples

Refusing a vaccine with a tiny risk while accepting a larger risk from the disease, because action feels riskier.
Judging a driver who swerves and causes harm more harshly than one who fails to brake.
A manager avoiding a tough decision, treating the harm of inaction as less their fault.

How to counter it

Compare outcomes, not action vs inaction — ask which choice leads to the better result.
Recognise that choosing not to act is still a choice you own.
Watch for using "I didn’t do anything" as a shield against responsibility.

The deeper point

It quietly makes "do no harm" mean "do nothing," even when doing nothing does the most harm. The outcome is what matters — but the mind keeps a separate, lighter ledger for the damage it merely allowed.

Frequently asked

What is the omission bias?: It is judging harm caused by action as worse than equal harm caused by inaction. We feel more responsible for damage we actively cause than for the same damage we passively allow.
What is an example of the omission bias?: Many people would refuse a vaccine with a small risk of harm while accepting a larger risk from the disease itself — because harm from acting feels worse than the greater harm from doing nothing.
What is the difference between omission bias and action bias?: They pull opposite ways. The omission bias favours inaction (doing nothing feels safer and less blameworthy); the action bias favours doing something even when inaction is better. Which dominates depends on context.

Action bias Status-quo bias Loss aversion Just-world hypothesis Second-order thinking Opportunity cost

Editorial synthesis © ReadGlobe 2026, drawing on Kahneman’s Thinking, Fast and Slow, the Tversky–Kahneman research program, and the primary cognitive-science literature. · Last reviewed 2026-05-29.