ley aptly notes of personal companionship—that its painful element is not difference of opinion, but discord of temperament—is equally apposite of intellectual pursuits in general. “Harmony of aim, not identity of conclusion, is the secret of the sympathetic life.” Such differences of opinion fall within the range of valid beliefs; those that do not—and many of them fall beyond the pale because of their discord of temperament, their alliance with other methods of fixing belief—may be variously characterized as error, fallacy, superstition, extravagance; and for the habits of mind that tend to the acceptance of false beliefs the terms illogicality and credulity are apposite. The former is commonly understood as referring to the proneness when confronted with the premises to draw false conclusions therefrom; the latter as a too great readiness to accept the premises on insufficient evidence. Yet in practice they are often found as close companions and appear at the summons of prejudice, ignorance, inertia, and of that weakness of judgment and vacillation of standards of belief that flourish, weed-like, when the scientific habit of mind is not assiduously cultivated.
It is important to illustrate that the forces that have been most productive of error in the past are not wholly shorn of their strength in the present; that these tendencies to act upon data credulously, with perverted logic and distorted evidence, however different the fashion of the garments in which they are paraded, are still recognizably the same persistent human frailties that detract from the complete appropriateness of the definition of man as a rational animal. It is further to be noted that quite too many of these misdemeanors are laid to the charge of ignorance; in truth ignorance cannot usually prove an alibi, but it remains to discover the influences that prevented the dispelling of the ignorance, and therein will be found the vera causa of the credulity. Mr. Lecky reminds those who would investigate the causes of existing beliefs that a change of opinion is apt to imply, more than anything else, a change in the habits of thinking. “Definite arguments are the symptoms and pretexts, but seldom the causes of the change.” “Reasoning which in one age would make no impression whatever,
