The scientific realism debate directly addresses the relation between human thought and the reality in which it finds itself. A core question: can we justifiably believe that science accurately describes the reality that lies beneath the limits of human experience? Exploring this question, the Element begins at the most foundational level of scientific realism, the endeavor to justify belief in the existence of unobservables by way of abduction. Raising anti-realist challenges, some much discussed in the literature but also some generally overlooked, it works its way toward more refined variants of scientific realism. Because it takes scientific realism to be the default position of many – scientific realists themselves often assuming it is the default position of scientists – the emphasis will be on the challenges. Those challenges will also motivate the variants of scientific realism traced. The Element concludes with an articulation of the author's own position, Socratic scientific realism.