In this discussion of where justification and understanding come to an end, Nagel undertakes to refute various forms of subjectivism. Defending rationalism, he argues that there are some thoughts that we simply cannot get outside of; thoughts that we cannot regard as mere psychological dispositions. The last word on philosophical disputes about the objectivity of any form of thought must lie in some unqualified thoughts about how things are. In the domains of logic and mathematics, certain basic propositions are immune to doubt being central to the framework of everything we can think. In the domains of ethics, science, or history, resistance to the external or subjective viewpoint comes from within these domains themselves. First‐order thoughts about ethics, science, and history are the decisive factor in response to any second‐order thoughts about their psychological character. Any criticism of the reasoning within these domains necessarily involves reasoning carried out at the same level of inquiry. Questions about how the capacity for rational thought is possible for a species like ours generate a pernicious fear of religion that Nagel seeks to dispel.