In time, English School authors have elaborated two versions of international society: the pluralist version and the solidarist version. This typology is an offspring of the order versus justice debate in international relations where pluralists prioritize order to justice, as an unjust system cannot be stable. Solidarists prioritize justice as an unjust system (even if it has order) is undesirable and ultimately unsustainable. This debate is a continuing argument between second-generation scholars that ties into international society as a core concept of international relations - the second basic argument of the English School.