According to radical scepticism, knowledge of the external world is impossible. Transcendental arguments are supposed to be anti-sceptical, but can they provide a satisfying response to radical scepticism? Especially, when radical scepticism is cast as posing a how-possible question, there is a concern that transcendental arguments are neither sufficient nor necessary for answering such question. In light of this worry, I argue that we can take a modest transcendental argument as a stepping stone for a diagnostic anti-sceptical proposal, and I (...) use a Wittgensteinian modest transcendental argument to illustrate my point. (shrink)