Arnold Brecht, Political Theory (The Foundations of Twentieth Century Political Thought) , Princeton, New Jersey ١٩٥٩, pp. ٢٩٨-٣٠١; Carl J. Friedrich, Man and His Government (An Empirical Theory of Politics, New York ١٩٦٣, pp., ٦٧, ٦٨; Max Weber on The Methodology of the Social Sciences, trans, and ed. E.A. Shils, H.A. Finch, New York ١٩٤٩, pp. ١-٤٧, Talcott Parsons, The Structure of Social Action, N.Y. ١٩٣٧, pp. ٥٩٣"٥٩٧. وللرجوع إلى مصادر أحدث, حول تطور ذلك الجدل انظر: W.D. Hudson, ed., The IS-Ought Question, New York ١٩٦٩, especially John Searl's Article: "How to derive Ought from Is", pp. ١٢٠-١٣٤. تكمن أهمية هذه المقالة الأخيرة في أنها تحتوي هجوما مباشرا على الأسس الفلسفية لما يسمى بحياد العلوم الاجتماعية. Cited by Fred M. Frohock, "Notes on the Concept of Politics: Weber, Easton Strauss," in: The Journal of Politics, Vol. ٣٦, No. ٢, Gainesville Florida, May ١٩٧٤, pp ٣٧٩-٣٨١; cf. D.C. Schwartz, "Toward a More Relevant and Rigorous^ Political Science", in The Journal of politics Vol. ٣٦,No. ١, Feb. ١٩٧٤, p. ١١٩; cf. also, MadeleineGrawitz, Methodes Des Sciences Sociales, Deuxieme Ed., Paris *٩٧٤> PP- *M> *٣٥> ٣IO-٣*٥> ٥°°; Bernard Crick, In Defence of Politics, p. ١٩٠,.