This third volume of this series develops further previous treatment of reasons, normativity, the meaning of moral discourse, and the status of morality. It engages with critics, and shows the way to resolution of their differences. This volume is partly about what it is for things to matter, in the sense that we all have reasons to care about these things. Much of the book discusses three of the main kinds of meta-ethical theory: normative naturalism, quasi-realist expressivism, and non-metaphysical non-naturalism, which this book refers to as non-realist cognitivism. This third theory claims that, if we use the word ‘reality’ in an ontologically weighty sense, irreducibly normative truths have no mysterious or incredible ontological implications. If instead we use ‘reality’ in a wide sense, according to which all truths are truths about reality, this theory claims that some non-empirically discoverable truths — such as logical, mathematical, modal, and some normative truths — raise no difficult ontological questions. This book discusses these theories partly by commenting on the views of some of the contributors to Peter Singer's collection Does Anything Really Matter? Parfit on Objectivity.