The two perils for law discussed in the last two chapters ‒ disagreement in morality and vagueness of language ‒ seem disparate. But law's awareness of both perils arises from a single source. The source is modern liberal law's understanding of the relation between law and other realms of discourse. From the standpoint of liberal law, disorder exists in intellectual realms beyond law. Law's language and morality must do better than nonlegal language and morality. The admonition to do better is a consequence of law's view of discourse outside law, and that understanding is a consequence of the conception of legality that stands at the center of liberal legal practice. Argument inside law works to ensure that disorder outside law stays outside. It works to dvelop law's own language and law's own morality. Formalizing argument develops a specifically legal language. Ideal argument develops a specifically legal morality. When formalization and idealization succeed, then the vagueness afflicting common language doesn't disable law, and the moral disagreement that happens outside law doesn't break out inside. But if law's distinctive processes should fail, then law's defenses are breached, and law lies open to disorder outside.