The rationality community is one of the brightest lights in the modern intellectual firmament.
Bryan Caplan, Professor of Economics, George Mason University
A Map that Reflects the Territory
Essays by the LessWrong community

Scott Alexander, Eliezer Yudkowsky, Wei Dai, Samo Burja, Sarah Constantin, Zvi Mowshowitz, Viktoria Krakovna, Alkjash, Paul Christiano, Ben Pace, Alex Zhu, Kaj Sotala, Rohin Shah, Georgia Ray, Abram Demski, Martin Sustrik, Patrick LaVictoire, Scott Garrabrant, Raymond Arnold, Valentine Smith, Andrew Critch, Jameson Quinn and Katja Grace

LessWrong is a community blog devoted to refining the art of human rationality. This is a collection of our best essays from 2018, as determined by our 2018 Review. It contains over 40 redesigned graphs, packaged into a beautiful set of 5 books with each book small enough to fit in your pocket.

Read the FAQ

Each year thousands of posts are written to LessWrong. Since 2019, users come together once a year to review and vote on the best posts from two years ago. This is our attempt to build an online forum that rewards truth-seeking content that can stand the test of time, rather than short-term attention-seeking. 41 of the most highly rated essays in last year's review have been compiled in this book set. Meanwhile, this year's review is just getting started.

A scientist does not just try to understand how life works, chemicals combine, or physical objects move. Rather, they use the general scientific method in each area, empirically testing their beliefs to discover what's true. Similarly, a rationalist does not simply try to think clearly about their personal life, how civilization works, or what's true in a single domain like nutrition or machine learning.

A rationalist is someone who is curious about the general patterns that allow them to think clearly in any area. They want to understand the laws and tools that help them make good decisions in general. The essays here explore many elements of rationality, including questions about aesthetics, artificial intelligence, introspection, markets, altruism, probability theory... and much more.

The essays from LessWrong have been one of my favorite sources of wisdom. Especially in our rapidly changing world, these writings are among those that I expect will continue to be read many decades from now.
Vitalik Buterin (Co-founder, Ethereum)
Each year thousands of posts are written to LessWrong. Since 2019, users come together once a year to review and vote on the best posts from two years ago. This is our attempt to build an online forum that rewards truth-seeking content that can stand the test of time, rather than short-term attention-seeking. 41 of the most highly rated essays in last year's review have been compiled in this book set. Meanwhile, this year's review is just getting started.
Whenever there’s a cutting-edge new idea making the rounds, Eliezer was writing about it 5-10 years ago. A deep dive into LessWrong will make you smarter.
Tim Urban (Author, "Wait But Why")
A scientist does not just try to understand how life works, chemicals combine, or physical objects move. Rather, they use the general scientific method in each area, empirically testing their beliefs to discover what's true. Similarly, a rationalist does not simply try to think clearly about their personal life, how civilization works, or what's true in a single domain like nutrition or machine learning.
Rationalists like Yudkowsky update their beliefs about the world as new information comes in, whereas many non-rationalists try to make new information fit their preconceived ideas... [In predicting the coronavirus pandemic] It seems like the rationalist community was ahead of most of the rest of us.
Scott Sumner (The Money Illusion, and Professor of Economics, George Mason University)
A rationalist is someone who is curious about the general patterns that allow them to think clearly in any area. They want to understand the laws and tools that help them make good decisions in general. The essays here explore many elements of rationality, including questions about aesthetics, artificial intelligence, introspection, markets, altruism, probability theory... and much more.
The rationality community is one of the brightest lights in the modern intellectual firmament.
Bryan Caplan (Professor of Economics, George Mason University)
A rationalist is someone who is curious about the general patterns that allow them to think clearly in any area. They want to understand the laws and tools that help them make good decisions in general. The essays here explore many elements of rationality, including questions about aesthetics, artificial intelligence, introspection, markets, altruism, probability theory... and much more.
This is not a book of essays about curiosity, but rather a book of essays exemplifying it. The authors were curious about something, they set out to explore it, and they wrote down what they learned for the rest of us.