Why Does Harmful Inaction Often Seem Less Wrong than Action?

Two people both want a tennis opponent to become unwell. One actively recommends food to which the opponent is allergic. The other sees the opponent order that food and deliberately says nothing. In experimental scenarios where intention and outcome were held constant, people tended to judge the active recommendation more harshly. This asymmetric evaluation of harmful action and harmful inaction is called omission bias.

Actions are more visible and are often treated as more direct causes of outcomes. Inaction resembles the default state in which nothing appears to have changed, so responsibility can feel weaker. Experiments reported by Spranca, Minsk and Baron in 1991 attempted to hold intentions, motives and consequences constant and still found this difference. A preregistered 2022 meta-analysis covering 21 samples and 49 effects found an overall moderate asymmetry, stronger for morality and blame than for decisions. Results nevertheless varied across studies.

Omission bias does not mean that action and inaction should always be treated alike in real life. A clear duty, knowledge of the risk, ability to intervene, and the possibility that intervention itself creates harm can all make genuine differences. The bias arises when these conditions are comparable but we still reduce blame simply because someone did not personally perform the harmful act.

A better check is not to force equal blame, but to ask separately: Was the outcome foreseeable? Could the person control it? What duty did they have? If we rewrite “doing nothing” as an explicit choice not to act, it often becomes easier to see how an omission can still participate in causation and responsibility.

https://www.sciencedirect.com/science/article/pii/002210319190011T
https://pubmed.ncbi.nlm.nih.gov/34496694/