Story of Psychology - Morton Hunt [137]
Galton based his estimate of the rarity of genius on the “law of deviation from an average.” That law had been worked out early in the century by mathematicians to express the distribution of errors in astronomic observations and of cards or numbers in games of chance. But it also applied to variations in human traits. In 1835 the Belgian astronomer Adolphe Quételet, using information about French conscripts, reported that a few men were very tall, a few very short, and the rest in between, with by far the largest number being average or close to it. The data, when plotted on a graph, yielded a bell-shaped curve, with most individuals in the center. The farther to either side of the midline one went, the fewer there were. The concept of the “curve of normal distribution” of human traits is so familiar today that it is hard to believe that in Quételet’s time it was a revelation.
Galton assumed that what was true of height must be true of other bodily characteristics, like brain weight, number of nerve fibers, sensory acuity—and, hence, mental capacity. If so, the mental ability of individuals followed a normal curve of distribution. He divided the curve of human intelligence into sixteen equal segments—eight above average, eight below—and from the shape of the curve calculated the proportion of the population in each segment. The two highest segments, he reckoned, would total only 248 people per million, which tallied with the figure of one in four thousand for obituary-based eminence. But a very small number were even farther out at the high end of the curve. They were the one in one million who were truly illustrious and who, he hoped to show, were born that way, not made or self-made:
I have no patience with the hypothesis … that babies are born pretty much alike, and that the sole agencies in creating differences between boy and boy, and man and man, are steady application and moral effort. It is in the most unqualified manner that I object to pretensions of natural equality. The experiences of the nursery, the school, the university, and of professional careers, are a chain of proofs to the contrary.6
Galton felt certain that in a “progressive” society (his term) such as Victorian England, innate ability was sure to be rewarded by success: “If a man is gifted with vast intellectual ability, eagerness to work, and power of working, I cannot comprehend how such a man should be repressed… [Rather,] he is sure to be welcomed with universal acclamation.”7
Heroic labor at his genealogical research yielded Galton the finding that of the 286 judges in his sample, about one in nine was the father, son, or brother of another judge; in addition, the judges numbered among their relatives many bishops, admirals, generals, novelists, poets, and physicians. The incidence of eminence in these families was hundreds of times greater than in the general population; the same was true of the other categories of eminent persons.
Summing up the data for all his categories of illustrious people, he reported that 31 percent had eminent fathers, 41 percent eminent brothers, and 48 percent eminent sons. Moreover, the closer the relationship between an eminent person and a relative, the greater the likelihood that the relative was eminent. Galton was satisfied that he had thoroughly proved his hypothesis—“that a man’s natural abilities are derived from inheritance, under exactly the same limitations as are the form and physical features of the whole organic world.”8
Contemporary psychologists can point to a number of naïve shortcomings in Galton’s methodology, in particular his failure to evaluate the environments in which the illustrious grew up; if most of them had been reared in strongly