Thomas Piecha is a philosopher, physicist, and computer scientist. His research interests include proof-theoretic and dialogical approaches in logic, the logical writings of Karl Popper, and the logical and physical foundations of computer science.

Kai Wehmeier is a professor of logic and philosophy of science at the University of California, Irvine. He has made contributions to mathematical and philosophical logic, formal semantics, the philosophy of language, and the history of analytic philosophy, with a special emphasis on Frege.

Chapter 1. Proof-theoretic semantics: An autobiographical survey (Peter Schroeder-Heister).- Chapter 2. Grundlagen der Arithmetik, §17: Part 1. Frege's anticipation of the deduction theorem (Göran Sundholm).- Chapter 3. Frege's class theory and the logic of sets (Neil Tennant).- Chapter 4. The validity of inference and argument (Dag Prawitz).- Chapter 5. Kolmogorov and the general theory of problems (Wagner de Campos Sanz).- Chapter 6. Disjunctive syllogism without Ex falso (Luiz Carlos Pereira, Edward Hermann Haeusler and Victor Nascimento).- Chapter 7. The logicality of equality (Andrzej Indrzejczak).- Chapter 8. Eight rules for implication elimination (Michael Arndt).- Chapter 9. Focusing Gentzen's LK proof system (Chuck Liang and Dale Miller).- Chapter 10. Intensional harmony as Isomorphism (Paolo Pistone and Luca Tranchini).- Chapter 11. A note on synonymy in proof-theoretic semantics (Heinrich Wansing).- Chapter 12. Paradoxes, intuitionism, and proof-theoretic semantics(Reinhard Kahle and Paulo Guilherme Santos).- Chapter 13. On the structure of proofs (Lars Hallnäs).- Chapter 14. Truth-value constants in multi-valued logics (Nissim Francez and Michael Kaminski).- Chapter 15. Counterfactual assumptions and counterfactual implications (Bartosz Wi¿ckowski).- Chapter 16. Some set-theoretic reduction principles (Michael Bärtschi and Gerhard Jäger).- Chapter 17. Comments on the contributions (Peter Schroeder-Heister).