Less Wrong is a community resource devoted to refining the art of human rationality which was founded in 2009. Site activity reached a peak in 2011-13 and a trough in 2016-17. This page mainly describes the history through 2016.
Around 2001 Yudkowsky had created the mailing list and IRC channel, and on them Yudkowsky frequently expressed annoyance, frustration, and disappointment in his interlocutors' inability to think in ways he considered obviously rational. After failed attempts at teaching people to use Bayes' Theorem, he went largely quiet from SL4 to work on AI safety research directly. After discovering he was not able to make as much progress as he wanted to, he changed tacts to focus on teaching the rationality skills necessary to do AI safety research until such time as there was a sustainable culture that would allow him to focus on AI safety research while also continuing to find and train new AI safety researchers.
LessWrong material was ultimately developed from Overcoming Bias, an earlier group blog focused on human rationality, which began in November 2006, with Eliezer Yudkowsky and Robin Hanson as the principal contributors.
In February 2009, Yudkowsky's posts were used as the seed material to create the community blog LessWrong, and Overcoming Bias became Hanson's personal blog. Some users were recruited via Eliezer's transhumanist SL4 mailing list.
The site's uses Reddit-style infrastructure. The ongoing community blog materials lead to significant growth and interest over the following years. At its peak it had over 15,000 pageviews a day.
During this period, popular fan-fiction HPMOR was started and finished.
Around 2013, many core members of the community stopped posting on Less Wrong, because of both increased growth of the Bay Area physical community and increased demands and opportunities from other projects. MIRI's support base grew to the point where Eliezer could focus on AI research instead of community-building, Center for Applied Rationality worked on development of new rationality techniques and rationality education mostly offline, and prominent writers left to their own blogs where they could develop their own voice without asking if it was within the bounds of Less Wrong. Collectively some of this diaspora forms the 'rationalist movement'.
Some other prominent ideas to grow out of the lesswrong community (by members of the community's actions) include:
Lesswrong is still active and activity can also be found in the diaspora communities:
As of 2016 the community is far less active than it once was. The forum stands, but submissions are down. The wiki has low traction and it is potentially in need to streamlining around remaining activity rather than its former glories.