 The first is effective agency—do humans have the ability to act as they wish to, in order to get what they desire? Aristotle thinks that effective deliberation and action presupposes the openness or contingency of the future—that what is going to happen is not necessary. Aristotle confronts an argument that tries to establish that the future is necessary, and hence that deliberation and action are futile. This argument, however, proceeds not from causal determinism, but from what might be called “logical determinism”—the thesis that, from eternity, statements about the future have had fixed truth values. The Epicureans, Stoics, and academic skeptic Carneades confront the same argument, but they also consider the relationship between “logical determinism” and causal determinism, and whether causal determinism is compatible with effective agency.