Science is always changing. always developing. because new factsÂ are discovered. new theories expounded and new thoughts developed.Â Hence it is always becoming a new knowledge. It thus becomes a new wayÂ of looking upon the facts and conditions of life and nature. Hence scienceÂ cannot remain the same for ever. In other words. science is an instrumentÂ for discovering new knowledge and developing new thoughts and new waysÂ of thinking. The same is also true of Political Science. It too is changing; it too is growing and developing constantly, as new facts are discovered andÂ new theories are expounded As I have explained in a chapter of this book,Â even in Pakistan Political Science has changed, though its progress is not soÂ fast as in the developed countries of the West. Many old theories wereÂ challenged or discarded and new ones introduced by various schools ofÂ political scientists and thinkers, especially in the Western countries. TheyÂ have influenced the teaching of Political Science in Pakistan also. Consequently, the syllabuses of various universities in our country haveÂ been revised and updated from time to time, especially after 1980.Â In view of the new syllabuses of the Pakistani universities, I haveÂ thoroughly revised my book. It was formerly entitled PRINCIPLES OFÂ POLITICAL SCIENCE. But in view of the changes and additionsÂ introduced in it. I have brought it out under a new title: POLITICALÂ SCIENCE THEORY AND PRACTICE. Though much of the old edition isÂ still retained in it. nevertheless all new theories and explanations of theÂ phenomena of politics have been incorporated in the new edition. I hopeÂ that it will not only present a comprehensive survey of the modemÂ developments in Political Science, but will also meet all the requirements ofÂ the teachers and students of the degree classes as prescribed in theÂ syllabuses of the Pakistani Universities. (For their convenience, theseÂ syllabuses are also copied in the beginning of this book).