 Perhaps because of its brevity and relative clarity, but also perhaps because of the hope it can be made ‘self-standing’ and independent of the (to some) disreputable machinery of transcendental idealism [see §3 of the entry on   Immanuel Kant], it is the Refutation that has  become the paradigm to many of a transcendental argument. While the  wisdom of this can be questioned (cf. Bell 1999), the Refutation undoubtedly makes a useful place for us to start.