A sentence, proposition, thought, or judgement is a posteriori (literally "after") if its truth depends on how our actual experience (experiment and observation) turns out. Many thing that truths of the empirical, or nonmathematical, sciences are entirely a posteriori, though rationalists and some recent philosophers such as S. Kripke & N. Chomsky seem to deny this (strictly, Kripke and Chomsky keep believing that some empirical and a posteriori truths are necessary). Some take synthetic and a posteriori to be equivalence. See a priori.