Introduction: dialectics in dialogue Thomas Bénatouïl; 1. Megara and dialectic James Allen; 2. Dialectic in the early Peripatos Paolo Crivelli; 3. Epicurus on dialectic David Sedley; 4. Dialectic as a subpart of stoic philosophy Katerina Ierodiakonou; 5. Stoic dialectic and its objects Jean-Baptiste Gourinat; 6. Dialectic in the Hellenistic Academy Luca Castagnoli; 7. Pithana and Probabilia Tobias Reinhardt; 8. Terminology and practice of dialectic in Cicero's letters Sophie Aubert-Baillot; 9. The sceptic's modes of argumentation Benjamin Morison; 10. Galen and middle Platonists on dialectic and knowledge Riccardo Chiaradonna.