 This long-standing debate prompted Alexander to develop an Aristotelian concept of fate by identifying it with the natural constitution of things, including human nature (On Fate, ch. 2–6). Since there is always the possibility that something happens against the natural and normal order of things, there are exceptions to what is ‘fated’ and there is room for chance and the fortuitous. Most of the treatise is occupied not with the defense of this Peripatetic position, but rather with attacks on the various aspects of the determinist position. Alexander claims to show why the Stoics’ attempt (though he nowhere names them) to defend a compabilitist position must fail. The determinists, he says, are neither entitled to maintain a coherent concept of luck and the fortuitous, nor of contingency and possibility, nor of deliberation and potency. The bulk of this polemical discussion concentrates on the difficulties for the Stoic position by claiming that their concept of fate makes human deliberation superfluous and therefore imports disastrous consequences for human morality and life in general (chs. 7–21). Alexander also presents, albeit in a dialectical fashion intended to lead to the defeat of the Stoic tenets, the arguments used by the Stoics in their defense of contingency, chance, and human responsibility. As he claims time and again, the Stoics can defend the use of these terms at best in a verbal sense. In addition, their notion of divine foreknowledge and prophecy turns out to be incoherent (chs. 22–35). The stringency and originality of Alexander’s critique cannot be discussed here (cf. Sharples 1983; Bobzien 1998). While his presentation is not free from repetition and while the order of the arguments leaves something to be desired, it is an interesting text that displays a lively engagement with the issues and quite some philosophical sophistication. He argues that truly free action requires that at the time one acts, it is open to one both to do and not to do what one does in fact then do. Thus Alexander originates the position later known as ‘libertarianism’ in the theory of free action. Alexander’s construction of an Aristotelian account of fate and divine providence that limits them to nature and its overall benign order clearly argues for a weak conception of fate; but it is the only one that Alexander regards as compatible with the principles of Aristotelian philosophy of nature and ethics. That the concept of fate greatly intrigued him is confirmed by the fact that he returns to the issue in his addendum (‘Mantissa’) to the treatise On the Soul and in some of his Problems (2.4.5, cf. Sharples 1983, esp. the Introduction).