Rationality learning resources

Websites that promote rationality, with a focus on epistemic rationality

• LessWrong, which describes itself as a "community blog devoted to refining the art of human rationality." Less Wrong additionally has its own wiki, which often contains quick summaries of rationality concepts and tends to do a good job of grouping together related posts. As of late 2017, an open beta of LessWrong 2.0 is taking place in an attempt to revive LessWrong.
• Slate Star Codex, a blog that applies the principles of rationality to the analysis of many questions of philosophy, psychology, culture, and society. Scott Alexander (Yvain on Less Wrong), the author of Slate Star Codex, has also created a map of the rationalist community which groups different websites/blogs/Twitter accounts by subject, and may be useful for finding more resources in an area of one's interest.
• Center for Applied Rationality website
• Overcoming Bias, a blog primarily written by Robin Hanson, that strives to uncover and correct for human bias and discover the truth.

Other websites that discuss issues related to rationality

• Bryan Caplan's blog posts on EconLog often discuss issues related to rationality and philosophy, although the blog is primarily focused on economics
• Gwern's website
• See the effective altruism learning resources page. Many learning resources for effective altruism use rationalist ideas. In particular, Paul Christiano's blog does.