In her 1921 book, The Space-Time Problem in Kant and Einstein, Ilse Schneider examines the foundations and consequences of the theory of relativity from an epistemological perspective. Beyond addressing detailed questions of early 1920s physics, it is a programmatic attempt to reconcile Kant’s transcendental idealism with Albert Einstein’s physics. The Kantian background puts the book in direct competition with Ernst Cassirer’s book Einstein’s Theory of Relativity, published in the same year. Schneider’s approach was largely ignored in the research compared with (...) Cassirer’s. What has not been considered so far is that Schneider and Cassirer represent two different interpretations of Kant, which they apply to Einstein’s physics. Recent Kant scholarship has differentiated these interpretations into the “metaphysical” and “epistemological dual-aspect” views. The former view can be found in the work of Schneider’s academic supervisor, Alois Riehl, and clearly distinguishes Schneider’s realist-inspired approach from Cassirer’s idealism. Given these differing views, it is necessary to be more precise when speaking of “immunization strategies” in the context of neo-Kantianism in order to make the differences between Schneider and Cassirer clear. Cassirer immunizes philosophy from the results of physics. In contrast, Schneider exposes philosophy much more strongly to physics. (shrink)