The primary philosophical topic explored under the rubric "weakness of the will" is roughly what Aristotle called akrasia. This classical Greek term is formed from the alpha privative (basically, a negation sign) and kratos, meaning "strength" or "power." The power at issue is the power to control oneself in the face of actual or anticipated temptation. So akrasia is deficient self-control. Self-control, in this sense, may be understood as constituted primarily by a robust capacity to see to it that one does what one believes to be best on the whole when tempted to do otherwise. The self-controlled person, Aristotle writes, "is in such a state as … to master even those [temptations of a certain kind] by which most people are defeated," and the akratic person "is in such a state as to be defeated even by those … which most people master...