  Recognizing that some individuals have invisible disabilities should remind us, Davis observes, of the extent to which we always are epistemologically dependent on people's disclosures of their own identities. Davis rejects the presumption that we can clearly separate voluntary from inadvertent limitations. Many cognitive and psychological limitations cannot be documented by reference to physical anomalies. Yet, Davis rightly says, experiences of them are no less real. She rejects the conviction that we can find physical correlates of anomalous cognitive or psychological functioning. Policies demanding that these kinds of cognitive and psychological limitations be documented by public demonstration or third-party confirmation should be abandoned, for they rely on mere faith in their having physical causes rather than on factual evidence that they do.