The article gives conceptual clarification on a distinction between ideal and nonideal theory by analyzing John Rawls´ theory as presented in his books “A Theory of Justice” and ”The Law of Peoples.“ The article tries to show the importance of ideal theory, while at the same time pointing out that the distinction, ideal and nonideal, needs further qualification. Further, the article also introduces the distinction of normative and descriptive into ideal and consequently nonideal theory. Through this four-fold distinction it is easier to establish the function of each theory and the separation of work-fields between philosophers, politicians and lawyers.