Philosophy of science attempts to reconstruct science as a rational cognitive enterprise. In doing so, it depicts a normative ideal of knowledge acquisition and does not primarily seek to describe actual scientific practice in an empirically adequate way. A comprehensive picture of what good science consists in may serve as a standard against which we evaluate and criticize actual scientific practices. Such a normative picture may also explain why it is reasonable for us to trust scientists - to the extent that they live up to the ideal - and to rely on their findings in decision-making. Likewise, a sound normative understanding of science exposes the limits of scientific understanding and prevents us from placing blind faith in scientists and experts. For these reasons, philosophy of science represents a useful resource and background theory for the practice and study of science communication. In this handbook article, we provide an opinionated introduction to philosophy of science by flashing a light on 22 central issues, which (we think) are of special interest to scholars and practitioners of science communication - and, in particular, to scholars and practitioners of external science communication.