Software patents are commonly criticised for being fuzzy, context-sensitive, and often granted for trivial inventions. More often than not, these shortcomings are said to be caused by the abstract nature of software - with little further analysis offered. Drawing on Plato’s Parmenides, this paper will argue (1) that the reason why software patents seem to be elusive is that patent law suggests to think about algorithms as paradigmatic examples and (2) that Plato’s distinction between two modes of predication and the (...) role of competence in his account of knowledge are helpful not only for conceptualising knowledge of algorithms, but also for understanding the limits of software patent regimes. (shrink)