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) due to the fact that 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.