Given the ubiquity and centrality of social and relational influences to the human experience, our conception of self-governance must adequately account for these external influences. The inclusion of socio-historical, externalist (i.e., "relational") considerations into more traditional internalist (i.e., "individualist") accounts of autonomy has been an important feature of the debate over personal autonomy in recent years. But the relevant socio-temporal dynamics of autonomy are not only historical in nature. There are also important, and under-examined, futureoriented questions about how we retain autonomy while incorporating new values into the existing set that guides our interaction with the world. In this paper, we examine these questions from two complementary perspectives: philosophy and neuroscience. After contextualizing the philosophical debate, we show the importance to theories of autonomous agency of the capacity to appropriately adapt our values and beliefs, in light of relevant experiences and evidence, to changing circumstances. We present a plausible philosophical account of this process, which we claim is generally applicable to theories about the nature of autonomy, both internalist and externalist alike. We then evaluate this account by providing a model for how the incorporation of values might occur in the brain; one that is inspired by recent theoretical and empirical advances in our understanding of the neural processes by which our beliefs are updated by new information. Finally, we synthesize these two perspectives and discuss how the neurobiology might inform the philosophical discussion.