  If there is a single, continuous thread that runs through the various thoughts about coercion surveyed above, I believe it could be identified as Lucas suggests with a concern for the ability of some agents to implement and enforce decisions about the activities of others. With the possible exception of Mill, who allows for a greater range of coercive methods than the others surveyed, this general idea seems to capture what one might have said was essential in the concept of coercion as pre-modern and modern political theorists employed it, by name or (in the case of Locke) by function.