The omission bias refers to our tendency to react more strongly to harmful actions than to harmful inactions, and judge them to be less moral. This bias extends so far that at times we prefer harm caused by inaction over lesser harm caused by the action. This bias largely stems from our bias towards what is deemed as “normal”, where inaction can more often be justified as normal. Similarly, we often make the distinction based on direct versus indirect causation – action is easier to classify as direct causation than is inaction.
For example, we tend to place greater blame on one who gets in a car accident when driving drunk (an action) than we do on that person’s friends who allowed them to drive drunk (an inaction).