The is–ought problem, as articulated by the Scottish philosopher and historian David Hume, arises when one makes claims about what "ought" to be that are based solely on statements about what "is". Hume found that there seems to be a significant difference between positive statements (about what is) and prescriptive or normative statements (about what ought to be), and that it is not obvious how one can coherently move from descriptive statements to prescriptive ones. Hume's law or Hume's guillotine is the thesis that, if a reasoner only has access to non-moral and non-evaluative factual premises, the reasoner cannot logically infer the truth of moral statements.