This introduction consists in a historical overview of the debate about practical irrationality, as illustrated by weakness of will. After a brief reminder of the discussions after Davidson, we consider three important moments of the debate: the ancient debate from Socrates to Xenophon, the medieval debate from Augustine to Buridan, and the modern debate after Descartes. We suggest that it is useful to distinguish weakness of will (a failure to act as one wills) from so-called strict akrasia (a failure to (...) will according to one's better judgment) and raise the question of the metaphysical underpinnings of the internalism/externalism debate. (shrink)