Rationality is the art of thinking in ways that result in accurate beliefs and good decisions. It is the primary topic of LessWrong.

Rationality is not only about avoiding the vices of self-deception and obfuscation, but also about the virtue of curiosity, seeing the world more clearly than before, and achieving things previously unreachable to you. The study of rationality on LessWrong includes a theoretical understanding of ideal cognitive algorithms, as well as building a practice that uses these idealized algorithms to inform heuristics, habits, and techniques, to successfully reason and make decisions in the real world.

Topics covered in rationality include (but are not limited to): normative and theoretical explorations of ideal reasoning; the capabilities and limitations of our brain, mind and psychology; applied advice such as introspection techniques and how to achieve truth collaboratively; practical techniques and methodologies for figuring out what’s true ranging from rough quantitative modeling to full research guides.

Note that content about how the world is can be found under World Modeling, and practical advice about how to change the world is categorized under World Optimization or Practical.

Formal / Theoretical	Techniques & Skills	Failure Modes
Conservation of Expected Evidence Decision Theory Game Theory Solomonoff Induction Utility Functions Value of Information Robust Agents	Techniques Focusing Trigger Action Planning/Patterns Goal Factoring Hamming Questions Identity Betting Forecasting & Prediction Concrete Forecasts Scholarship & Learning Replicability Dark Arts	Bucket Errors Compartmentalization Goodhart’s Law Heuristics and Biases Mind Projection Fallacy Rationalization Motivated Reasoning Confirmation Bias Sunk-Cost Fallacy Fallacies Pica Pitfalls of Rationality
Communication	Models of the Mind	Other
Conversation Inferential Distance Information Cascades Steelmanning Disagreement Philosophy of Language Decoupling vs Contextualizing	Subagents Predictive Processing Perceptual Control Theory	Practice & Philosophy of Science Rationality Quotes Gears-Level Center for Applied Rationality

This list is not comprehensive! The tagging system is new. Many needed tags have not been created and/or added to the above list.

What we're calling "rationality"

A good heuristic is that rationality is about cognitive algorithms. Rather than being a synonym for true or optimal, th...

Good Explanations (Advice)