George Boolos was Professor of Philosophy, Massachusetts Institute of Technology.

• * Studies on Set Theory and the Nature of Logic * Introduction to Part I * The Iterative Conception of Set * Reply to Charles Parsons's "Sets and Classes" * On Second-Order Logic * To Be Is to Be a Value of a Variable (Or to Be Some Values of Some Variables) * Nominalist Platonism * Iteration Again * Introductory Notes to Godel *1951 * Must We Believe in Set Theory? * Frege Studies * Introduction to Part II * Gottlob Frege and the Foundations of Arithmetic * Reading the Begriffsschrift * Saving Frege from Contradiction * The Consistency of Frege's Foundations of Arithmetic * The Standard of Equality of Numbers * Whence the Contradiction? *1879? * The Advantages of Honest Toil over Theft * On the Proof of Frege's Theorem * Frege's Theorem and the Peano Postulates * Is Hume's Principle Analytic? * Die Grundlagen der Arithmetik, 82-83 (with Richard Heck) * Constructing Cantorian Counterexamples * Various Logical Studies and Lighter Papers * Introduction to Part III * Zooming Down the Slippery Slope * Don't Eliminate Cut * The Justification of Mathematical Induction * A Curious Inference * A New Proof of the Godel Incompleteness Theorem * On "Seeing" the Truth of the Godel Sentence * Quotational Ambiguity * The Hardest Logical Puzzle Ever * Godel's Second Incompleteness Theorem Explained in Words of One Syllable