Luis von Ahn on reCaptcha and Duolingo

Patrizia pointed me to a TEDxCMU talk by Luis von Ahn on The Next Chapter in Human Computation. von Ahn is known for Captcha and reCaptcha (which he talks about in the first 8 minutes of the talk.) In this talk he introduces his team’s new crowdsourcing project duolingo which aims to translate the web while teaching people a second language. Instead of paying $500 for RosettaStone software you can learn a language by translating progressively more complex sentences from the web.

von Ahn also calls this a “Fair Business Model for Education”. (There is actually a slide with this phrase.) His argument is that since most of the world doesn’t have the money for software, duolingo presents a fair way for them to contribute labour in return for learning a language. I note that the fair business model could apply not just to language education, but other types of education. How could you monetize the teaching of philosophy (or ethics)? What would people do to learn that could also benefit someone else?