A collection of essays on fundamental issues regarding scientific knowledge. Contents: Systematic Essays: Science and the Epistemic Authority of Logical Analysis, Jay F. Rosenberg; Varieties of Understanding, Robert Brandom; Theory Families, Plausibility and the Defense of Modest Realism, Rom Harre; Scientific Rationality and Its Reconstruction, Jurgen Mittelstrass; Conservatism and the Data Base, William Lycan. Historical Essays: Darwin's Achievement, Philip Kitcher; "A Purely Scientific Temper": Victorian Expressions of the Ideal of an Autonomous Science, Robert E. Butts.