 Political philosophy is, in one respect, simply that part or extension of moral philosophy which considers the kinds of choice that should be made by all who share in the responsibility and authority of choosing for a community of the comprehensive kind called political. In another respect, it is a systematic explanatory account of the forms of political arrangement that experience and empirical observation show are available, with their characteristic features, outcomes, and advantages (and disadvantages and bad aspects and consequences). Though in form descriptive and contemplative, and thus non-practical, this aspect of political philosophy remains subordinate, in its systematization or conceptual structure, to the categories one finds necessary or appropriate when doing moral and political philosophy as it should be done, that is, as practical thinking by one whose every choice (even the choice to do nothing now, or the choice to do moral or political philosophy) should be a good use of opportunity.