priorknowledge

Priorknowledge, usually called a priori knowledge in philosophy, refers to propositions that can be known independently of experience. Such claims are justified through reason, deduction, or the analysis of concepts rather than through sensory observation. By contrast, a posteriori knowledge depends on empirical evidence obtained from the world. A priori knowledge is often described as necessary and universal, though debates about necessity and certainty are common.

Common examples include logical truths (for example, that all bachelors are unmarried) and certain mathematical statements (such as 2+2=4). Some philosophers also count some logical laws as a priori, while mathematics is often treated as analytic a priori. Kant distinguished analytic a priori truths from synthetic a priori truths, the latter being informative about the world yet knowable independently of particular experience. The idea of synthetic a priori is central to discussions about how some principles appear to structure experience while remaining non-empirical in justification.

Historically, rationalists such as Descartes and Leibniz argued for the primacy of a priori knowledge, whereas empiricists like Hume emphasized the role of experience. In contemporary philosophy, the status of a priori knowledge is debated, with positions ranging from conceptualism and nativism to attempts to derive justification from linguistic or cognitive practices or from empirical investigation of cognition.

The debate over the scope and reliability of a priori knowledge continues to shape discussions in logic, mathematics, epistemology, and the philosophy of science.