The factor in societal evolution corresponding to heredity in organic evolution is tradition. . . . Heredity in nature causes the offspring to resemble or repeat the present type; tradition in societal evolution causes the mores of one period to repeat those of the preceding period. - Keller, Societal Evolution, p. 212.

Heredity is the basal principle in all discussions of progress, whether in biology or sociology. It means simply continuity; a quality once established tends to persist. The plants and animals of any one generation resemble their parents in most respects; they tend to "breed true"; "like produces like." So also in society. A primary group, having once formed about some leader or in connection with some occupation, tends to keep the same character. Public opinion, once established, is a difficult thing to change. A social class, once formed, will move on indefinitely in the same current of thought unless something happens to force a change. An institution, as was shown at some length in Chapter VIII (Organizations And Institutions), is a group of persons who are organized in such a way as to hold themselves and their successors to some fixed ideal. Their government is the mechanism on which they depend most of all to do this.

It is more than tradition, however, that holds society to its old ways. Tradition, as ordinarily understood, means oral delivery. But delivery through literary remains cannot be overlooked. In cases requiring exactness and uniformity, as with much in law and science, literary form of communication is more important than oral. Then there are other material remains in endless variety. The technology of the past comes to us largely in the form of tools and machines. The location of our national capital was first an idea in the heads of a few men at a dinner table; next it was an act of Congress in written form; now, unsuitable as it is, it cannot be changed, because to do so would render worthless a billion dollars' worth of land and buildings. All attempts to bring the metric system into use in this country have been frustrated, not by the difficulty of teaching it to children, or even of getting adults to learn it and think in terms of it, but by the impracticability of using it to describe objects in common use and to make computations regarding them.

How, for instance, would the piece of lumber known as a "two-by-four" be designated in metric terms? How could we express measures of land in hectares when the greater part of the country is already laid out in rectangular blocks of a round number of acres each? The piece of land known as a "forty," such as has been sold millions of times and will be sold many millions of times more, would have to be reckoned as 16 hectares, 18 ares, and 80 centares. We might discontinue making "two-by-fours" and make "five-by-tens" (centimeters) instead, but the "forties" will always be with us.

What one generation receives from its predecessor is, first of all, a vast material equipment, some of it in continuous use like houses and railroads, some of it used only intermittently like books in libraries, and some simply abandoned like the old canals of Ohio. Then there are the knowledge and habits which are acquired by observation and cooperation as well as by oral delivery. Now to call all of this "tradition" is to give that word a technical meaning for sociology much different from its common meaning. It would seem better to call it" social inheritance," and to call the process by which it is received "social heredity." That this is appropriating biological terms should be no valid objection. The more the various sciences adopt a common terminology for things which are fundamentally alike, the easier each science will be of acquisition and the richer its content.

... It is inheritance; for it shows the attainments of the fathers handed on to the children; but it is not physical heredity, since it is not transmitted physically at birth.

It is hereditary in that the child cannot escape it. It is as inexorably his as the color of his eyes and the shape of his nose. He is born into a system of social relationships just as he is born into a certain quality of air. As he grows in body by breathing the one, so he grows in mind by absorbing the other. The influence is as real and as tangible; and the only reason that it is variable in its results upon different individuals is that each individual has his physical heredity besides, and the outcome is always the outcome of the two factors, - natural temperament and social heredity. ... - Baldwin, Social and Ethical Interpretations, 4th ed., pp. 69, 70.

The problem here, then, is to see how that chain of heredity is broken. In order to have progress there must first of all be something new. How do new organisms take their beginning? How is a new variety of plants developed, or a new breed of cattle? How does any group of persons ever get away from its social heritage? How does a caste come to break its traditions? What makes institutions grow and change? We have seen in the preceding chapter that change is going on everywhere, and always has been. Let us try to set in order, first, the methods by which social variation comes about, and then the causes which lie back of it.