Until humanism and psychology are more suitably defined than they are at present the task of establishing their relations is hazardous. Psychology is still in a primitive state: its basic problems and principles are disputed, its relation to the other sciences is undetermined, and its method is loose and unsystematic. That it may be a science, however, is indubitable. The constitution of human nature is open to analysis: human behaviour no less than the stars and plants may be observed and hypothesis may be employed to order its seeming irregularities. But the common scientific ground of purpose which underlies the differences of psychological theories does not unite the humanists, and the problem of stating the nature and scope of humanism is correspondingly difficult. The absence of a common scientific ground, of an accepted subject matter and a technique, enables any man interested in human activities to call himself a humanist and to maintain his contention, whereas no man, unless technically trained, will consider himself a psychologist. He may observe society and deliver himself of apothegms and epigrams that characterise people truly--like the French moralists, La Rochefoucauld, La Bruyère, and Joubert. He may trace the influence of ideas on conduct, as Mr. Babbitt has done. But that is ethics and philosophy, not psychology. Psychology limits itself to studying how human beings behave and to reducing their most complex actions to primitive elements. Ethics evaluates their activities and judges them. So, however confusing the positions of contemporary psychologists and humanists, if we keep in mind the formal aspects of psychology and ethics, a study of the relations of the two may be instructive. Upon psychology as a science, as upon physics and chemistry, humanism can have nothing to say. It may examine the logic of psychology and criticise its presuppositions, although that is properly the task of the cosmologist, like Mr. Whitehead. But towards the conclusion of psychology, the “laws” it may formulate, humanism’s only possible attitude is one of interested acceptance. An ethics should not prescribe the limits of science, nor dictate the nature of its results. And if the science deals successfully with human actions, ethics, instead of criticising, should respect its results, that ideals may not be founded on ignorance and fancy but rather on knowledge.