A “Dear Economist” correspondent once asked me why people post clips of classic comedies on YouTube, or go to the trouble of writing online reviews, given that there seems to be nothing in it for them. A textbook economics model would say that people would not, in fact, post online reviews or contribute to YouTube. And my answer, in brief, was that they don’t. Far more people read books than write reviews of them, and far more watch YouTube videos than post them. As a broad defence of rational economic man, my answer wasn’t too bad; but as a way of understanding online volunteering, it was useless.
《親愛的經濟學家》的一位讀者曾經寫信問我，爲什麼看上去無利可圖，還會有人在YouTube上發佈經典的搞笑影片，或者費心在網上撰寫評論？按照教科書上的經濟學模型，人們不應該在網上撰寫評論或者在YouTube上發佈影片。簡單地說，我的答案是他們並沒有這樣做。讀書的人遠遠多於寫評論的人，看影片的人也遠遠多於上傳影片的人。作爲對理性經濟人的寬泛辯護，我的答案還算不錯，可惜對於理解在線志願行爲並沒有幫助。