These rational arguments stipulate that all reality fall within the scope of human rationality. This is seems both a necessary pre-condition--what else are we

These rational arguments stipulate that all reality fall within the scope of human rationality. This is seems both a necessary pre-condition--what else are we really using?--but it invites the question: what if there is something beyond that scope (however you care to label it) driving what is in view? All I'm after here is the recognition of the stipulation.