Pruss analyzes three paradoxes of infinity: Thomson’s Lamp, the Grim Reapers, and a die guessing game. The best explanation of what goes wrong, according to Pruss, is that the paradoxes all violate a certain principle about causation and infinity, namely that nothing can have an infinite causal history. A corollary of this principle is that there is a first cause. Pruss then shows how this result invites a joint project where atheists and theists may work together to investigate the nature of the first cause.