The eighteenth-century German rationalist tradition is, broadly speaking, committed to (what I call) ‘the principle of rational cognition’: the grounded must be rationally cognizable from its sufficient ground. Whereas the prevailing view takes the fundamental challenge to rationalist paradise to stem from the principle of sufficient reason, I argue that it instead stems from this principle: How is it possible to rationally cognize anything at all from its ground? By investigating the opposing responses of two of Leibniz’s most influential immediate (...) successors, Christian Wolff and Christian Crusius, we find no easy way to remain in rationalist paradise. (shrink)