This dissertation is a collection of three essays centered around outstanding fundamental problems in the field of moral psychology. These fundamental problems concern both metaphysical and methodological disagreements – namely, what is the subject-matter of moral psychology? And what are the methods for the investigation of that subject-matter? The first chapter examines the problem of marking the domain of moral psychology by isolating its subject-matter and the various methodologies for investigating it. By building from a minimal core of shared agreement, researchers should be able to classify different branches of moral psychology by both subject-matter and method of investigation while being quietist about the correct methodology. This is turn allows for the construction of a taxonomy of moral psychological approaches that allows researchers to efficiently locate the direct source of disagreements. The second chapter examines Lawrence Kohlberg’s research program and identifies a particular assumption that guides that program while blocking further progress in the field. That assumption concerns the relation between normative theorizing and descriptive categorization, such that the explanations for why one moral theory is superior to another mirrors stages of moral development. By abandoning this assumption and other assumptions in its local vicinity, researchers could make progress without being bogged down in first-order normative disagreement. The third chapter looks to a recent debate concerning whether neuroscience is normatively significant. Against a standard interpretation of the debate in Anglophone philosophy that the argument for the normative insignificance of neuroscience is sound, I argue that the critique is only partly successful and not for the reasons commonly recognized. Rather than object to the program of demonstrating the normative significance of neuroscience on normative grounds, we ought to object to the program on descriptive grounds. Each chapter proceeds through arguments rooted in philosophical analysis and reflections on findings in the social and natural sciences – in particular, history, psychology, economics, sociology, anthropology, cognitive science, and neuroscience.