pure

not mixed with anything sensible. Although its proper opposite is 'impure', Kant normally opposes 'pure' to 'empirical'.

[A2/B3] Used by Kant to characterize a subset of all a priori knowledge, viz. "when there is no admixture of the empirical". He adds in explanation, "thus the proposition, `every alteration has its cause', while an a priori proposition, is not a pure proposition, because alteration is a concept which can be derived only from experience". Thus whereas we can have a priori knowledge about some concepts which are derived from experience, pure a priori knowledge is that about concepts of which we an derive a priori, e.g., pure intuitions (space and time), and the pure concepts of the understanding (the categories). [A20/B34] As this suggests, representations (e.g., intuitions and concepts) can be pure, along the same lines. Representations can be pure. Kant writes, "I term all representations pure (in the transcendental sense) in which there is nothing that belongs to sensation [i.e., "given" experience]" all intuitions (save those of space and time) are thus empirical, and as are many concepts (e.g.,the concept of alteration, but not that of cause or substance).