A scientific ontology is a view about what a scientific theory says exists. Longstanding philosophical debate on this issue divides into two broad camps: anti-realists, who think scientific theories are committed to the existence only of those things that can be observed, and realists, who hold that these theories are also committed to unobservables, such as subatomic particles. In Scientific Ontology: Integrating Naturalized Metaphysics and Voluntarist Epistemology (Oxford University Press, 2017), Anjan Chakravartty argues that the debate is philosophically “indefeasible” because the views rest on different background “epistemic stances”, or bundles of attitudes that generate different assessments of the epistemic risk attached to scientific claims. Chakravartty, who is Apignani Foundation Chair and Professor of Philosophy at the University of Miami, elaborates his view that scientific ontology always includes an a priori metaphysical element and that epistemic stances are voluntarily adopted. He also considers the implications of his account regarding worries about whether ontological claims are inevitably perspectival and the rationality of opposing stances and the ontologies they ground.