 We can divide metaethical positions into two kinds: cognitivist and non-cognitivist. Cognitivists hold that moral statements—statements such as “Lying is wrong” and “Courage is a virtue”—have truth-values, being either true or false. Cognitivists maintain that when one sincerely makes a moral statement in an ordinary context, one believes the proposition expressed by the statement. Non-cognitivists hold that moral statements are not truth-evaluable: moral statements are neither true nor false, being more akin to utterances such as (a) “Haggis, YUCK!” or (b) “Take the haggis away!” Just as, when one sincerely utters (a) or (b), one does not express a belief, but does something else, non-cognitivists maintain that one does something other than express a belief when one makes a moral statement. The early non-cognitivists A.J. Ayer (1936) and R.M. Hare (1952) maintained that moral statements were akin to utterances (a) and (b) respectively, that is, they express either emotive reactions or commands. Other forms of non-cognitivism propose different accounts of exactly what one does when one makes a moral statement (see entry on  moral cognitivism vs. non-cognitivism).  Since non-cognitivism holds that we do not express beliefs when we make moral statements, there is no reason for non-cognitivists to think that there are any moral beliefs—according to non-cognitivism, even though moral statements typically have the form of declarative sentences, there are no moral propositions that correspond to them. If there are no moral beliefs or propositions, there is no a priori moral justification or a priori moral knowledge. So, the question of whether some moral propositions can be justified a priori really comes up only in the context of cognitivism.