One of the most difficult problems in political philosophy is the justification of the very terms it uses. The texts of W. B. Gallie and W. Connolly, on which this book draws, emphasize the possibility of justification occurring only when the terms are taken as essentially contested. The debates are generated through theoretical encounters of authors who have dissimilar systems of values. The book points out an internal connection between debates about terms and never-definitively resolved debates about social aims, values, and ethical norms. Thus, political theory and philosophy must understand and take into consideration the meanings given to terms by actors, often accompanied by intentions, values, and purposes of use of such terms.