a priori

(Latin ‘from what comes before’) in logic, an argument that is known to be true, or false, without reference to experience; the converse of a posteriori.

Space, time, reality, and negation exist independently of experience and arguments from these are a priori. Immanuel Kant asserts that we do not derive these concepts from experience, but that through their application we acquire experience. In morality also he declares that the ideas implied in the words ‘good’ and ‘bad’ are innate and imperative in every mind, independently of actual observation. In current usage, the term a priori refers to whatever seems not to derive from experience.