once unchallenged authority is proved to be highly fallible. Its spell is gone. It at once appears, for example, that common sense has had a history, and that it has varied with times and places. The absurdities of yesterday are the common sense of to-day; the common sense of yesterday is now obsolete and quaint. The crank of the sixteenth century was the man who said that the earth moved; the crank of the twentieth century is the man who says that it does not. Moreover, once common sense is thus reflected upon, it is seen to be in part, at least, the result of wholly irrational forces, such as habit and imitation. What has been long believed, or repeatedly asserted, acquires a hardness and fixity from that fact; in the future it is always easier to believe, more difficult to disbelieve, than anything recent or novel. And what others about us believe, we tend unconsciously to reflect in our own belief, just as our speech catches the accent and idioms of our social circle. Furthermore, a belief once widely diffused takes on the authority of established usage. It is supported by public opinion, as anything normal or regular is supported; unbelievers are viewed with hostile suspicion as unreliable and incalculable. "You can never tell what they will do next." Or they are forcibly persecuted as a menace to the public peace. I have called habit and imitation "irrational" forces. By that I mean that they have no special regard for truth. They operate in the same way to confirm and propagate a bad way of thinking as a good way of thinking. It does not follow that common sense is necessarily mistaken; indeed reasons can be adduced to show that common sense is a very good guide indeed. But if so, then common sense is justified on other grounds; it is not itself the last court of appeal. Common sense, despite its stability and vogue, perhaps on account of its stability and vogue, is open to criticism. We cannot be sure that it is true; and it may positively stand in the way of truth through giving an unwarranted authority to the old and familiar, and through shutting our minds so that no new light can get in.
The philosopher, then, is one who at the risk of being thought queer, challenges common sense; he sets himself against the majority in order that the majority may be brought to reflect upon what they have through inertia or blindness taken for granted. He is the reckless critic, the insuppressible asker of questions, who doesn't
