Hume's fork, in epistemology, is a tenet elaborating upon British empiricist philosopher David Hume's emphatic, 1730s division between "relations of ideas" versus "matters of fact." (Alternatively, "Hume's fork" may refer to what is otherwise termed "Hume's law", a tenet of ethics.) As phrased in Immanuel Kant's 1780s characterization of Hume's thesis, and furthered in the 1930s by the logical empiricists, Hume's fork asserts that all statements are exclusively either "analytic "a priori"" or "synthetic "a posteriori"," which, respectively, are universally true by mere "definition" or, however apparently probable, are unknowable without exact "experience".