This book defends a form of naturalistic and relativistic moral realism. The guiding intuition is that any society needs to be characterized by a social moral code in order to enable its members to live together successfully. According to the "society centred theory", it follows that certain moral codes are justified. And according to the "standard-based theory" of normative judgment, it follows that corresponding moral propositions may be true. The book also introduces a new perspective on reasons and rational choice.