Foreword -- Part  I: Introduction -- Chapter 1. The Roman Heritage -- Chapter 2. Bonus Theoreticus, Malus Practicus?.-Chapter 3.What is the Doctrinal Study of Law? -- Part II: The Foundations of Legal Thinking -- Chapter  4. Lawyer´s Dilemma -- Chapter 5. On Language-Games -- Chapter 6. The Foundations of Knowledge -- Chapter 7. On the Ontology of Law -- Chapter 8. A Moral Point of View -- Chapter 9. The Three Notions of Liberty -- Part III:  Between Realism and Idealism -- Chapter 10. What is Science? -- Chapter 11. Legal Realism Reinterpreted  -- Chapter  12.Outlines of the New Rhetoric -- Chapter  13. Scientific Inference - An Example -- Part IV:  On the Doctrinal Study of Law -- Chapter 14. From the Constitutional State to the Welfare State -- Chapter  15.Two Types of Norms -- Chapter  16 . The Formal Validity, Efficacy and Acceptability of Norms -- Chapter  17. The Procedure of Legal Reasoning -- Chapter18. The Sources of Law -- Chapter 19. One Right Answer? -- Chapter 20. On the Systematisation -- Chapter 21. Change or Development? -- Bibliography -- Index.

This book is a summary of the author’s 40 years of research in the fields of civil law and the philosophy of law. The main focus is on the two main tasks in the doctrinal study of law: the interpretation and systematisation of legal norms. In this regard, Professor Aarnio deals with the theory of argumentation as well as with its foundations - i.e., with the ontology, epistemology and methodology of legal thinking - and develops the ideas that were first presented in The Rational as Reasonable (Kluwer 1987) in all of these dimensions. The work includes an updated discussion on the writings of Robert Alexy, Jûrgen Habermas, Ronald Dworkin and Alf Ross. A focal point of view concerns the distinction between positivism and non-positivism, in which the core of the criticism focuses on Scandinavian realism.