 Recent philosophy of international law has pursued a great variety of questions. For present purposes, they can be broadly grouped into two categories, although the boundaries between them are not sharp. First, there are conceptual questions, such as whether international law is genuinely an instance of “law” and, if it is, how it is related to the municipal legal orders associated with individual states; there are also conceptual questions relating to key ideas employed in international legal discourse, whether these be general ideas such as “sovereignty”, “the state”, or “legitimacy”, or ideas associated with specific international legal sources or doctrines, such as “customary international law”, “jus cogens”, and “human rights”. Such questions are discussed mainly in sections 2 and 3 of this entry.