I will consider how the notion of incommensurability, as championed by Parfit (Reasons and persons, 1984), Griffin (Well-being: its meaning, measurement and importance, 1986), Chang (Ethics 112:659–688, 2002), and Hare (Philos Perspect 23:165–176, 2009), might affect both the argument from slight pain (which suggests God’s non-existence can be inferred from the merest stubbing of one’s toe) and Leibniz’s reply to this argument. I conclude that the notion of incommensurability may ultimately strengthen Leibniz’s general position.