<p>This chapter articulates Adam Smith's philosophy of science. The first section emphasizes the significance of Smith's social conception of science—science takes place, not always comfortably, within a larger society and is itself a social enterprise in which our emotions play a crucial role. Even so, in Smith's view science ultimately is a reason-giving enterprise, akin to how he understands the role of the impartial spectator. The second and third sections explain Smith's attitude to theorizing and its relationship, if any, to Humean skepticism. Smith distinguishes between theory acceptance and the possibility of criticism; while he accepts fallibilism, he also embraces scientific revolutions and even instances of psychological incommensurability. His philosophy is not an embrace of Humean skepticism, but a modest realism. Finally, the chapter explores the implications of Smith's analysis of scientific systems as machines.</p>