 Although the lines that separate one theory from another are not always distinct, philosophical justifications of political obligation nowadays usually take the form of arguments from consent, fair play, membership, or natural duty. Some philosophers advance a hybrid of two or more of these approaches, and others hold, as the concluding section shows, that a pluralistic theory is necessary. For the most part, though, attempts to justify a general obligation to obey the law follow one of these four lines of argument.