Certainly we would not regard a physician of 1800 as "evil" simply because he treated his patient in a manner that later would be shown to be more harmful than helpful, provided that he acted honestly, based on the facts available to him. On the other hand, if a doctor of a later time persisted in bleeding his patients regardless of their malady, if he refused to examine the new evidence—in short, if he refused to think—we would be entirely justified in condemning his behavior. Similarly, we shall find in Section 5 that certain kinds of political systems are fundamentally inimical to human life. The root evil in such systems, however, is no single governmental action, but rather the refusal of the supporters of such systems to allow themselves to comprehend the consequences, including the long-run effects, of their policies.

Errors in human action may be honest or dishonest, or they may involve some combination of the two. In the case of dishonest error, an individual acts destructively because he or she has evaded the responsibility of thinking. Even if one has consistently and honestly borne the latter responsibility, however, one may still occasionally make mistakes, because every human being's context of knowledge is inevitably limited (cf. p. 2.4:16).