The unfit, in the sense of Darwin and of biology in general, are those whose hereditary type is so unsuited to the conditions of life that it tends to die out, or at least suffer relative diminution in numbers, under the action of these conditions—as white families tend to die out in the tropics. In other words, they have an inferiority due to heredity, and this inferiority is of such a character that they do not leave as many children to continue their race as do those of a superior or fitter type. It is very questionable whether any great part of the poor answer the description in either of these respects. As to the first, it is the prevailing opinion with those most familiar with the matter that their inferiority, except possibly where a distinct race is in question, as with the Negroes, is due chiefly to deficient nurture, training and opportunity, and not to heredity. This view is supported by the fact that under the conditions which a country of opportunity, like the United States, affords, great masses of people rise from poverty to comfort, and many of them to opulence, showing that the stock was as capable as any. Something of this sort has taken place with German and Irish immigrants, and is likely to take place with Jews, Slavs and Italians. As to elimination, it is well known that only poverty of the most extreme and destructive kinds avails to restrict propagation, and that the moderately poor have a higher rate of increase than the educated and well-to-do classes. It is, in fact, far more the latter that are the “unfit” in a biological sense than the former. The truth is that poverty is unfitness, but in a social and not a biological sense. That is to say, it means that feeding, housing, family life, education and opportunity are below the standards that the social type calls for, and that their existence endangers the latter in a manner analogous to that in which the presence of inferior cattle in a herd endangers the biological type. They threaten, and to a greater or less degree actually bring about, a general degradation of the community, through ignorance, inefficiency, disease, vice, bad government, class hatred (or, still worse, class servility and arrogance) and so on. But since the unfitness is social rather than biological, the method of elimination must also be social, namely, the reform of housing and neighborhood conditions, improvement of the schools, public teaching of trades, abolition of child-labor and the humanizing of industry.