Dictionary.net

Characterizing that kind of reasoning which deduces consequences from definitions formed, or principles assumed, or which infers effects from causes previously known; deductive or deductively. The reverse of a posteriori.

Applied to knowledge and conceptions assumed, or presupposed, as prior to experience, in order to make experience rational or possible.

Characterizing that kind of reasoning which deduces consequences from definitions formed, or principles assumed, or which infers effects from causes previously known; deductive or deductively. The reverse of a posteriori.

Applied to knowledge and conceptions assumed, or presupposed, as prior to experience, in order to make experience rational or possible.

The correlative of a posteriori, the one implying the cause, the other the effect. The argument a priori is a mode of reasoning by which we proceed from the antecedent cause to the consequent effect, or from anticipation rather than from experience; mathematical proofs are examples of a priori reasoning. The argument a, posteriori is the opposite, and reasons from the effect to the cause, from the individual case to the law, or generally from experience, and not from anticipation.