 Yet another debate about the nature of universals and concepts looms in the background of this debate. How do we know universals or concepts? The Buddhist introduce the doctrine of apoha to provide the resources for constructing concepts from sensory content to further the nominalist project of explaining thought and language in a world of particulars. In response to Buddhist nominalism, Nyāya philosophers present a defense of realism in the course of which they argue for a theory of real perceivable universals. This debate will be the focus of secion 4.