More Precisely is a rigorous and engaging introduction to the mathematics necessary to do philosophy. It is impossible to fully understand much of the most important work in contemporary philosophy without a basic grasp of set theory, functions, probability, decision theory, and modality. More Precisely is written for people who wish to engage with contemporary philosophical writing but first need to fill gaps in their technical knowledge. Eric Steinhart provides lucid explanations of many basic mathematical concepts and sets out most commonly used notational conventions. He also demonstrates how mathematics applies to fundamental issues in various branches of philosophy, including metaphysics, philosophy of language, epistemology, and ethics. This second edition adds a substantive section on decision and game theory, as well as a chapter on information theory and the efficient coding of information.