4.5 out of 5 stars

In “This Much I Know,” as in his Tony-winning “Eureka Day,” playwright Jonathan Spector manages to celebrate humanity while skewering human nature. In interlocking narratives, three actors frequently (but impressively) switch among multiple roles: A psychology professor draws out his sort-of white-nationalist student, the professor's wife goes on a Russian research odyssey, and Josef Stalin's daughter emerges as a freedom-seeking protagonist in that research. Adapting ideas (albeit sometimes awkwardly) from psychologist Daniel Kahneman, Spector has constructed a fascinating, funny maze of a play; characters keep passing one another as they turn corners, seeking a way forward. — Adam Z. Horvath

At 59e59 Theaters, through Oct. 19, 2025; 59e59.org (Review date: Oct. 7, 2025)