A political philosopher has to be primarily interested in truth. Past philosophies are studied with an eye on coherence and consistency. The authors of the classics in political theory are superior because they were geniuses and measured in their writings. Strauss scrutinises the methods and purposes of the ‘new’ political science and concludes that it was defective when compared with classical political theory, particularly that of Aristotle. For Aristotle, a political philosopher or a political scientist has to be impartial, for he possesses a more comprehensive and clearer understanding of human ends. Political science and political philosophy are identical, because science consisting of theoretical and practical aspects is identical with philosophy. Aristotle’s political science also evaluates political things, defends autonomy of prudence in practical matters and views political action as essentially ethical. These premises Behaviouralism denies, for it separates political philosophy from political science and substitutes the distinction between theoretical and practical sciences. Its argument is not arbitrary, but derives its validity from the aggregate of experiences to which it must permanently refer for empirical control.