Abstract

The ‘No Ought From Is’ principle (or ‘NOFI’) states that a valid argument cannot have both an ethical conclusion and non-ethical premises. Arthur Prior proposed several well-known counterexamples, including the following: Tea-drinking is common in England; therefore, either tea-drinking is common in England or all New Zealanders ought to be shot. My aim in this paper is to defend NOFI against Prior’s counterexamples. I propose two novel interpretations of NOFI and prove that both are true