Kant insists that the use of concepts must be subject to empirical conditions if they are to have objective validity. This article analyses Kants distinction between empirical and transcendental truths. Since transcendental concepts are pure concepts without spatio-temporal content, their objective validity is of the same second-order kind as that of unschematized categories. This characteristic of transcendental concepts implies that the cognitive powers picked out by them are not particular psychological mechanisms, but rather abstract functional structures. Transcendental concepts owe their (...) objective validity to the realizability of the functional structures by empirical cognizers like humans. This relation in turn helps to explain the nature of transcendental truths. (shrink)