This paper argues that Epicurus held a non-reductionist view of mental states that is in the spirit of Davidson's anomalous monism.1 We argue for this conclusion by considering the role that normative descriptions play in the peritropē argument from On Nature 25. However, we also argue that Epicurus was an indeterminist. We can know that atoms swerve because we can know that we make choices that are up to us and this is incompatible with the ancestral causal determination of mental states by atomic processes. Epicurus escapes the traditional criticism of indeterminist libertarians because the swerve is not meant to explain how choices may be free. The anti-reductionist stance on the mental means that nothing about atomic processes could possibly explain any particular mental event. Moreover, because of the practical and therapeutic nature of Epicurean philosophy, it is not necessary that Epicurus provide an explanation of how the swerve subserves freedom of choice. We know all that we need to know for eudaimonia when we know that some choices are up to us.