The
omission bias is an alleged type of
cognitive bias. It is the tendency to judge harmful actions as worse, or less moral than equally harmful omissions (inactions) because actions are more obvious than inactions. It is contentious as to whether this represents a systematic error in thinking, or is supported by a substantive
moral theory. For a
consequentialist, judging harmful actions as worse than inaction would indeed be inconsistent, but
deontological ethics may, and normally does, draw a moral distinction between doing and allowing. The bias is usually showcased through the
trolley problem.