Условие:
The purpose of this book is twofold. The first is to detect and understand the forces which determine political relations among nations, and to comprehend the ways in which those forces act upon each other and upon international political relations and institutions. In most other branches of the social sciences there would be no need to emphasize this purpose. It would be taken for granted, because the natural purpose of all scientific undertakings is to discover the forces underlying social phenomena and how they operate. However, in approaching the study of international politics, such emphasis is not misplaced. As Professor Grayson Kirk has so ably said:
\nUntil recent times the study of international relations in the United States has been dominated largely by persons who have taken one of three approaches. First there have been the historians who have considered international relations merely as recent history, in which the student is handicapped by the absence of an adequate amount of available data. A second group, the international lawyers, have properly concerned themselves primarily with the legal aspects of inter-state relations, but they have seldom made a serious effort to inquire into the fundamental reason's for the continuing incompleteness and inadequacy of this legal nexus. Finally, there have been those who have been less concerned with international relations as they are than with the more perfect system which these idealists would like to build. Only recently - and belatedly - have students undertaken to examine the fundamental and persistent forces of world politics, and the institutions which embody them, not with a view to praise or to condemn, but merely in an effort to provide a better understanding of these basic drives which determine the foreign policies of states. Thus the political scientist is moving into the international field at last.
\nProfessor Charles E. Martin has taken up Professor Kirk's theme by pointing to "the problem which faces the students and the teachers of international relations more than any other, namely, that dualism we have to face in mov-
