I. The Traditional Syllogism.- 1. Whately and the Revival of Formal Logic.- 2. Euclid and the Syllogism.- 3. Reid, Hamilton and Mansel on Relational Inferences.- II. First Thoughts on the Copula.- 1. The Two Copulas.- 2. First Notions of Logic.- 3. Relations and Identity.- III. Generalizing the Copula.- 1. The Abstract Copula.- 2. The Bicopular Syllogism and the Composition of Relations.- 3. Oblique Inferences and De Morgan's Dictum.- IV. The Problem of Form and Matter.- 1. "Sundry Perversions of the Syllogistic Form".- 2. The Material Copula.- 3. De Morgan's Response.- 4. The Issues.- 5. Heads and Tails.- V. The Logic of Relations.- 1. Philosophical Preliminaries.- 2. General Logic of Relations.- 3. Properties of Relations.- 4. Singular Relational Syllogisms (Unit Syllogisms).- 5. Quantified Relational Syllogisms.- 6. The Limited Unit Syllogism.- 7. The Ordinary Syllogism and the Relational Syllogism.- VI. The Logic of Relations and the Theory of the Syllogism.- 1. The Two Views.- 2. Objective View-The Basic Account.- 3. Objective View-The Relational Form.- 4. The Subjective View.- VII. Logic and Mathematics.- 1. "A Mathematical Logic".- 2. Algebraic Techniques and Analogies in Logic.- 3. Logic and Geometrical Proof.- 4. Logic and Algebraic Reasoning.- 5. Form in Algebra and Logic.- 6. Conclusions.- VIII. A Rigorous Formulation.- 1. Basic Issues.- 2. The System D.- 3. Properties of Inclusion and Identity.- 4. De Morgan's Basic Identities.- 5. Theorem K.- 6. Properties of Relations.- 7. Additional Inclusion Laws.- 8. The Full System of Three-Relation Terms.- 9. De Morgan's Logic with Identity.- 10. More Properties of Relations.- 11. A Surrogate for Quantification Theory.- 12. Postscript-1864.- 13. De Morgan's Conjectures.- Notes.

The middle years of the nineteenth century saw two crucial develop­ ments in the history of modern logic: George Boole's algebraic treat­ ment of logic and Augustus De Morgan's formulation of the logic of relations. The former episode has been studied extensively; the latter, hardly at all. This is a pity, for the most central feature of modern logic may well be its ability to handle relational inferences. De Morgan was the first person to work out an extensive logic of relations, and the purpose of this book is to study this attempt in detail. Augustus De Morgan (1806-1871) was a British mathematician and logician who was Professor of Mathematics at the University of London (now, University College) from 1828 to 1866. A prolific but not highly original mathematician, De Morgan devoted much of his energies to the rather different field of logic. In his Formal Logic (1847) and a series of papers "On the Syllogism" (1846-1862), he attempted with great ingenuity to reformulate and extend the tradi­ tional syllogism and to systematize modes of reasoning that lie outside its boundaries. Chief among these is the logic of relations. De Mor­ gan's interest in relations culminated in his important memoir, "On the Syllogism: IV and on the Logic of Relations," read in 1860.