26 The Eugenics Review positive eugenics. Not only this, but we know from various sources that raising the standard of life among the poorest classes almost invariably results in a lowering of their fertility. In so far, therefore, as differential class-fertility exists, raising the environmental level will reduce any dysgenic effects which it may now have. Returning, however, to the more important aspect of the eugenic knowledge to be gained by leveling up the social environment, I anticipate that at the bottom, the social problem group, though shrinking in size, will be left, clearly marked out by its inadequate performance in the new and favourable conditions, as a well-defined target for measures of negative eugenics such as segregation and sterilization; and that minor targets of the same nature will emerge out of the present fog, in the shape of nests of defective germ-plasm inspissated by assortative mating and inbreeding, such as have been imaginatively glimpsed by Lidbetter and others. I further anticipate that the professional classes will reveal themselves as a reservoir of superior germ-plasm, or high average level notably in regard to intelligence, and therefore will serve as a foundation-stone for experiments in positive eugenics. And I anticipate that society will tap large resources of high ability that are at present unutilized, thus facilitating the social promotion of at least certain fitter elements; and without social promotion we cannot proceed to reproductive encouragement. This is the scientific ideal at which we should aim. Like many other ideals, we shall not achieve it; but any approach to it will help us towards a more certain knowledge. Science, however, is control as well as knowledge; and new practice may advance theory as much as new theory lay the basis for practice. This is especially true for the social sciences, where, as we have seen, rigorously controlled experiment, on the pattern of pure physics or physiology, is impossible, and problems must frequently be solved [italics]ambulando[end italics]. We make a partial experiment which is simultaneously pure and applied science. The experiment is both an attempt to gain knowledge and an effort to realize a wish, a desired control. It is planned, like more crucial experiments in the natural sciences, to verify deductions from known facts. In so far as the desired end is attained, the deductions are verified and knowledge is increased; and even if the control is not attained, knewledge is increased, though not to the same extent. This more empirical mode of attack must also be used in eugenics. We must attempt to control the change of social environment and at the same time to control the change of human germ-plasm, along lines which appear likely to yield tangible and desirable results. It is the results which interest us. Admirable germ-plasm unable to realize itself owing to unfavourable conditions does not interest us: nor do the most alluring social conditions, if they permit or encourage the deterioration of the germ-plasm. Thus the two attacks must be planned in relation to each other, and also in relation to practicability. [italics]The Dysgenic Character of our Present Social System[end italics] When we think along these lines, we shall find, I believe, that a system such as ours, a competitive and individualist system based on private capitalism and public nationalism, is of its nature and essence dysgenic. It is dysgenic both in the immediate respect of failing to utilize existing reservoirs of valuable genes, and also in the long-range tasks of failing to increase them, failing to trap and encourage favourable mutations, and failing to eliminate harmful mutations. Under our social system, the full stature or physique of the very large majority of the people is not allowed to express itself; neither are the full genetic potentialities of health permitted to appear except in a small fraction of the whole, with a consequent social waste of energy and time, not to mention a waste of individual happiness which is formidable in extent; and finally, innate high ability is encouraged or utilized only with extreme inadequacy. For the first two wastes, ignorance is partly responsible, but in the lower economic strat, poverty [end]