"It remains a scandal to philosophy and to human reason", Kant complains, "that the existence of things outside us ... must be accepted only by faith ..." (KRV, B xl (a)). The expression "outside us", however, is "unavoidably ambiguous in meaning, sometimes signifying what as thing in itself exists apart from us, and sometimes what belongs solely to outer appearance" (A 373). The existence of things outside us can only be established, in Kant's view, if we interpret "outside us' as meaning "that which can be experienced as external".