Does Seneca entirely reject the utility of dialectical study for moral improvement? No, I argue here. Focusing on Letter 87, I propose that Seneca raises and disarms objections to formal Stoic arguments in order to help moral progressors avoid backsliding and advance towards ethical knowledge. I trace this method back to Chrysippus and show that reading Letter 87 in this Chrysippean framework yields a satisfying explanation of its otherwise puzzling features.