When people accept the notion that none of us is completely immune from error, they also implicitly accept that no person, no matter who he is or how strongly he believes, is above possible correction. If at any moment I can be wrong and you can be wrong and so can everybody else, all without being aware of it, then none of us can claim to have finally settled any dispute about the state of the external world. No one, therefore, is above critical scrutiny, nor is any belief.

