While many people today might turn to ancient Sanskrit philosophers for meditation or yoga, probably few would turn to them for help with difficult contemporary problems, such as what counts as "fake news" or navigating Internet debates. Philosopher Malcolm Keating argues that, in fact, a group of premodern Indian philosophers known as "Nyāya" have important things to say about how we can distinguish truth from falsity and reason well together, both of which are crucial to living a good life. In _Reason in an Uncertain World_, Keating teaches us what's distinctive in Nyāya approaches to knowledge and discussion, explaining these ideas in relationship to ordinary examples readers can understand. What are the limits of our reasoning? What counts as good evidence for our beliefs? How do we know if someone is a trustworthy source of information? What do we do when we are gripped by doubt? When is a debate with someone worth our time, and how can we discuss contentious topics? The answers to these questions are as relevant today as they were in ancient India. There, they were the focus of Nyāya philosophy, one of the most influential traditions of Indian philosophy, which few outside of scholarly communities have heard of.