Bill Dalessandro is a philosopher of science and mathematics at Oxford University. Today Bill joined us to discuss proofs -- specifically, what it means for a proof to be fixable, what it means for a proof to be transferable, and the apparent tension between these notions. This work built on prior work by Northeastern's Don Fallis, who attended the talk and participated in the lively and fascinating conversation that ensued. We also discussed what it's like to work in an interactive theorem prover. In such an environment, you don't really make mistakes -- because the prover doesn't let you -- but you might prove the wrong thing, and/or, you might not learn much despite having proven something. This was a great talk with a great with a really strong discussion section and we hope you enjoy it as much as we did!