Mathematical knowledge: a case study in empirical philosophy of mathematics Benedikt L~we, Thomas M~ller, Eva Wilhelmus Abstract: In this paper, we present a paradigm for the philosopher of mathematics who takes mathematical practice seriously: Empirical Philosophy of Mathematics. In this philosophical paradigm, we use empirical methods (from sociology, psychology, cognitive science, didactics) to evaluate empirical questions connected to or derived from philosophical positions about mathematics. The paper presents a concrete case study. Keywords: empirical philosophy of mathematics; methodology; epistemology; mathematical knowledge