Although there is considerable disagreement among theorists about what should count as an "overt act" in the crafting of criminal law, one strategy of many theorists is to define an act as a "willed bodily movement." Moore reflects this approach in defining an act as a volition causing a bodily movement. As a corollary to this understanding, Moore has developed a pair of arguments, one metaphysical and the other normative, against liability for most omissions. This essay argues that the flaws in Moore's arguments stem from his broader theory of action. His metaphysical claim against omissions as criminal acts is an outgrowth of his definition of an act. Since omissions are not bodily movements caused by volitions, omissions do not constitute actions in Moore's view. In metaphysical terms, he claims that omissions are "literally nothing at all." Moore's normative claim presupposes a standard argument against imposing liability for omissions. This argument reasons that it is both unfair and an intrusion upon freedom to require that persons act in a particular way regardless of individual circumstances and the personal values that determine individual choices. Moore's arguments, however, fail to fully appreciate that the presence of a positive duty, such as paying taxes, can allow treating an omission as a positive action directed toward some foreseeable harm. It is not difficult to conceive of failure to uphold certain positive duties as having as much force (both moral and legal) as a positive act with harmful consequences. In effect, there is much more to human agency and its consequences than Moore suggests. The act requirements must identify those key features of human agency common to every complex action the criminal law proscribes. Under such a conception, omissions would be viewed as actions that fail to comply with positive actions required by law. Omissions would thus be parasitic upon positive duties. The issue for consideration in omissions would be whether or not an individual met the threshold of adequate opportunity to have performed the positive action. 40 notes