What is the thesis of the play Proof by David Auburn?
The three dominant themes of Proof are that (1) genius is not suited to the mundane day-to-day world and may turn to madness under the pressures and performance of life. (2) Mathematics is provable but trust is unprovable and must be engaged in as an act of faith whether there are irrefutable grounds for trust or not. (3) The third is the contemplation of the inheritability of genius and/or of madness: Catherine's writing looks very much like her father's; her proof is elegant and full of genius also like her father's
Based on these three themes in Proof, it seems the suggested thesis is that trust in people is like trust in mathematical proofs, which may both have emotional instability at their core. Specifically, if a mathematical problem is proved by a series of elegant calculations, it must be trusted; similarly, if individuals prove their integrity and character by a series of elegant actions, then they must be trusted. The difficulty, as illustrated by Catherine's relationships with Claire and Hal, is in the ambiguous nature of proofs of the human abstractions of integrity and other inner qualities.