Legal scholars often prescind to moral philosophy to try to solve legal puzzles or paradoxes and to shape the positive law by reference to the seemingly pure and uncluttered lessons derived from within first-order moral theory. This chapter aims to do something quite close to the opposite. By looking at the structure of negligence law and certain concepts within it and by exhibiting their principled bases, it generates possible solutions to some of the problems about negligence that have troubled moral philosophers. These include: whether conduct that would ordinarily be called “negligent” can qualify as a breach of moral duty even if it was solely the product of inadvertence; whether it matters to the blameworthiness of a negligent actor that her conduct caused no harm; and whether a person whose negligent conduct is purely a product of inadvertence can properly be blamed or held responsible for injuring another. In the domain of negligence law, which contains “negligence,” “duty,” and “legal responsibility” in the form of legal liability, the answer to all three analogous questions is emphatically “yes,” and tort law explains why. Moving back to moral questions, we see our way to defensible answers to those questions and we also see why the questions present themselves as so difficult.