No precise and definitive boundaries can be placed around a subject as comprehensive as political science. It shares many points of common interest with other social disciplines.
History - the bond between the political scientist and the historian is obvious in the observation that "history is past politics and politics present history." The political scientist frequently adopts a "historical approach" and employs knowledge of the past when he seeks to interpret present and probable developments in political phenomena.
Economics - until late in the 19th century, political science and economics (the study of the production, distribution, and conservation, and consumption of wealth) were coupled under the name of political economy. Today, these fields are jointly concerned with the fact that economic conditions affect the organization, development, and activities of states, which in turn modify or even prescribe economic conditions. The political scientist regularly adopts an "economic approach" when seeking to interpret such matters as "public financial policies" and government regulation of business.
Geography - geopolitics (a science concerned with the study of the influences of physical factors such as population pressures, sources of raw materials, geography, etc. upon domestic and foreign politics) indicates one approach which a political scientist frequently must adopt to help explain such phenomena as the early growth of democracy in Great Britain and the United States and its retarded growth in certain Continental Europe, and the rise of authoritarian governments in developing countries.
Sociology and Anthropology - the political scientist, the sociologist (who specializes in the study of "society as a whole"), and the anthropologist (who studies "mankind" in relation to physical, social and cultural development) are all deeply concerned with the origins and nature of social control and governmental authority, with the abiding influences of race and culture upon society, and with the patterns of collective human behavior.
Psychology - the political scientist as well as the psychologist promotes studies of the mental and emotional processes motivating the political behavior of individuals and groups. One of the many topics which the political scientist handles from a "psychological approach" is that of public opinion, pressure groups, and propaganda.
Philosophy - the concepts and doctrines of Plato, Aristotle and Locke (and other universal thinkers about the state) are important to the specialist in academic philosophy and also to the political scientist. These concepts are the underlying forces in the framing of constitutions and laws. The political scientist considers the branch of philosophy called ethics, too, when he contemplates the moral background of proposed changes in social legislation.
Statistics and Logic - the political theorist must possess a broad scientific background and a knowledge of current political problems, and he must employ scientific methods in gathering and evaluating data and in drawing conclusions. These involve a proper application of statistical procedures for the quantitative measurement of social phenomena and of logical procedures for the analysis of reasoning.
Jurisprudence - this branch of public law is concerned with the analysis of existing legal systems and also with the ethical, historical, sociological, and psychological foundations of law. A comprehension of the nature of law (whether the "natural law" or the "divine law") and of statutes enacted by legislatures is indispensable to the political theorist. Law and state are inseparable. All states proclaim laws, effective within their jurisdictions, and enforce them through a system of penalties. To maintain a full understanding of the facts of political life, the political scientist has to combine the legal with the extralegal viewpoints.