If moral requirements flow from a requirement to improve the way things are in the broadest possible sense, and we cannot change that, then there are no moral requirements.

Robert Adams (1974) argues that modal realism leads to surprising results in moral philosophy. The modal realist says that the way things are, in the broadest possible sense, is not a contingent matter, since we can’t change the nature of the pluriverse. Hence we cannot do anything about it. So if moral requirements flow from a requirement to improve the way things are, in this broadest possible sense, then there are no moral requirements. Lewis rejects the antecedent of this conditional as some