tl;dr: Thinking out loud with another person produces better reasoning than solo thought because verbalizing forces precision, and a listener's real-time reactions catch drift and surface hidden assumptions—a view supported by Mercier & Sperber's argumentative theory of reason, Vygotsky's ZPD, and Clark & Chalmers' extended mind. Remote work, async defaults, and LLMs erode this "dialogue dividend," and LLMs specifically tend toward sycophancy, agreeing with users rather than pushing back unless explicitly prompted (e.g., third-person reasoning), and even then only temporarily. Protect unscheduled conversation time and actively ask people and models to argue the other side.