Frege on Knowing the Fundamental Laws of Logic

If Frege’s logic, a Begriffsschrift, is to be used to determine the logicist thesis, it cannot neglect the epistemic nature of its fundamental laws. Within such a Begriffschrift, one is entitled to use the judgement stroke only if one knows the asserted content. The question, then, arises: how do we know a fundamental law of logic? As such a law cannot be demonstrated by laws prior in the order of explanation, it has to be known in a non-mediated way, on the basis of one’s understanding its content. If we can know a law of logic in such a non-mediated way, it is called self-evident (unmittelbar einleuchtend). For Frege’s logicist project, it is essential that the self-evidence of the fundamental laws of logic and arithmetic is not based on spatial or time intuition. To understand this special form of self-evidence, one can make use of Frege’s idea of logical capacity, which is nothing but our capacity to judge. It is thus possible to give an account of the self-evidence of the fundamental laws of logic without introducing any psychological element.