Have you read the challenge published last summer by Brown, Sokal, and Friedman to the Fredrickson and Losada work on positivity tipping points? How about Barbara Fredrickson’s response? Paul Lee read both and sent this letter with his thoughts. We are publishing Paul’s letter is to acknowledge both the challenge and the response. We also want to celebrate science as an evolving discipline where it is important both to generate ideas and to challenge them.