In summary, to the extent that interventions into the marketplace accomplish their objectives at all, they do so only by means of force or the threat of force. This point can hardly be overemphasized, because of the common illusion that the law operates in a voluntary and peaceful manner. With regard to individuals in class (2) on the previous page, for example, it is sometimes erroneously stated that they comply "voluntarily" with the law, because they maximize their individual value scales, in the context of an artificially restricted range of available options. If this sense were assigned to the word, however, then all human action would be "voluntary"; praxeology's most fundamental principle, after all, is that individuals act to maximize their purposes, as defined through their value scales (p. 4.4:1). The term "voluntary" would therefore cease to provide us with a cognitively useful distinction. As we showed in Section 1, valid concepts must be "based on objective differences of kind among the units they subsume, differences which must be grasped in order to understand reality" (p. 1.3:45). In this course, therefore, the concept voluntary is understood to apply to actions that are not constrained by force, including the threat of force. The concept force was developed in detail in pp. 4.5:8-12.

For example, suppose that an armed rapist tells a woman: "Cooperate or I'll slit your throat." If she allows him to proceed, she maximizes her value scale, within the context of her available options, yet her choice is very clearly involuntary: its effect is praxeologically similar to that which would result if the thief had tied her in place, making resistance futile.