Preface. 1. Philosophical Background and Program of the Study. 2. The Logical Background: A.D. 1-Logics. 3. The Logical Explication of Hume's Thesis. 4. The General Hume Thesis GH. 5. The Special Human Thesis SH. 6. Weakened Vesions of Hume's Thesis in A.D. 1- Logics with Bridge Principles. 7. A.D. 1-Logics with Weak Alethic Fragments: As A Subjective Propositional Attitude. 8. Generalizations. 9. Some Applications to Ethical Arguments. 10. The Problems of Identity and Existence. 11. Are There Analytic Bridge Principles? A Philosophical Investigation. 12. Are Synthetic Bridge Principles Scientifically Justifiable? Appendix. Notes. Bibliography.

Can OUGHT be derived from IS? This book presents an investigation of this time-honored problem by means of alethic-deontic predicate logic. New in this study is the leitmotif of relevance: is-ought inferences indeed exist, but they are all irrelevant in a precise logical sense. New proof techniques establish this result for very broad classes of logics. A profound philosophical analysis of is-ought bridge principles supplements the logical study. The final results imply incisive limitations for the justifiability of ethics as opposed to empirical science.