Introduction : doing science in a complex world. Science by humans ; Science in a complex world ; The payoff : idealizations and many aims -- Complex causality and simplified representation. Causal patterns in the face of complexity ; Causal patterns ; Causal complexity ; Simplification by idealization ; Reasons to idealize ; Idealizations' representational role ; Rampant and unchecked idealization -- The diversity of scientific projects. Broad patterns : modeling cooperation ; A specific phenomenon : variation in human aggression ; Predictions and idealizations in the physical sciences ; Surveying the diversity -- Science isn't after the truth. The aims of science ; Understanding as science's epistemic aim ; Separate pursuit of science's aims ; Understanding, truth, and knowledge ; The nature of scientific understanding ; The role of truth and scientific knowledge -- Causal pattern explanations. Explanation, communication, and understanding ; An account of scientific explanation ; The scope of causal patterns ; The crucial role of the audience ; Adequate explanations -- Levels and fields of science. Levels in philosophy and science ; Going without levels ; Against hierarchy ; Prizing apart forms of stratification ; The fields of science and how they relate -- Scientific pluralism and its limits. The entrenchment of social values ; How science doesn't inform metaphysics ; Scientific progress.