Without any grip of the notion of a rule and an exception, the general idea of judging people's heredity breaks down and is useless. For this reason: that if everything is the result of a doubtful heredity, the judgment itself is the result of a doubtful heredity also. Let it judge not that it be not judged. Eugenists, strange to say, have fathers and mothers like other people; and our opinion about their fathers and mothers is worth exactly as much as their opinions about ours. None of the parents were lunatics, and the rest is mere likes and dislikes. Suppose Dr. Saleeby had gone up to Byron and said, "My lord, I perceive you have a club-foot and inordinate passions: such are the hereditary results of a profligate soldier marrying a hot-tempered woman." The poet might logically reply (with characteristic lucidity and impropriety), "Sir, I perceive you have a confused mind and an unphilosophic theory about other people's love affairs. Such are the hereditary delusions bred by a Syrian doctor marrying a Quaker lady from York." Suppose Dr. Karl Pearson had said to Shelley, "From what I see of your temperament, you are running great risks in forming a connection with the daughter of a fanatic and eccentric like Godwin." Shelley would be employing the strict rationalism of the older and stronger free thinkers, if he answered, "From what I observe of your mind, you are rushing on destruction in marrying the great-niece of an old corpse of a courtier and dilettante like Samuel Rogers." It is only opinion for opinion. Nobody can pretend that either Mary Godwin or Samuel Rogers was mad; and the general view a man may hold about the healthiness of inheriting their blood or type is simply the same sort of general view by which men do marry for love or liking. There is no reason to suppose that Dr. Karl Pearson is any better judge of a bridegroom than the bridegroom is of a bride.
An objection may be anticipated here, but it is very easily answered. It may be said that we do, in fact, call in medical specialists to settle whether a man is mad; and that these specialists go by technical and even secret tests that cannot be known to the mass of men. It is obvious that this is true; it is equally obvious that it does not affect our argument. When we ask the doctor whether our grandfather is going mad, we still mean mad by our own common human definition. We mean, is he going to be a certain sort of person whom all men recognise when once he exists. That certain specialists can detect the approach of him, before he exists, does not alter the fact that it is of the practical and popular madman that we are talking, and of him alone. The doctor merely sees a certain fact potentially in the future, while we, with less information, can only see it in the present; but his fact is our fact and everybody's fact, or we should not bother about it at all. Here is no question of the doctor bringing an entirely new sort of person under coercion, as in the Feeble-Minded Bill. The doctor can say, "Tobacco is death to you," because the dislike of death can be taken for granted, being a highly democratic institution; and it is the same with the dislike of the indubitable exception called madness. The doctor can say, "Jones has that twitch in the nerves, and he may burn down the house." But it is not the medical detail we fear, but the moral upshot. We should say, "Let him twitch, as long as he doesn't burn down the house." The doctor may say, "He has that look in the eyes, and he may take the hatchet and brain you all." But we do not object to the look in the eyes as such; we object to consequences which, once come, we should all call insane if there were no doctors in the world. We should say, "Let him look how he likes; as long as he does not look for the hatchet."