 Conservative scepticism is quite distinct from Cartesian or external world scepticism, therefore, since the latter scepticism is based on reason; rather, it is sceptical about the claims of theoretical reason, in politics and ethics. Nor does its scepticism constitute a critique of society in the Marxist sense. For conservatives, society rests on prejudice, not reason; prejudice is not irrational, but simply unreasoning. Burke advocated educated prejudice as an antidote to its bigoted forms—arguably, not a rejection of reason, but a scepticism about its inordinate pretensions. Philosophers might speculate about why we have the duties that we do, but prejudice makes us act, without having to calculate all the consequences—or indeed to reason about ends. This is not the irrationalism of Nietzsche or Freud, for whom much of human behaviour is irrationally driven, but rather, a non-rationalist standpoint. It is sceptical about proposals of reform based on a priori commitment to a value such as freedom or equality. (See  2.3 on Burke  below) In elucidating conservatism, one should distinguish between the metaethical claim that abstract values do not exist or are not worth pursuing, and the epistemic challenge “how are these values be accessed in practice?” Conservatism is primarily an epistemic standpoint. Conservatives believe that values of justice, freedom, and truth are important and should be pursued by the state, but they interpret those values in a concrete fashion.