A Guide to become a Neo-Rationalist.
To rationally be a rationalist—meaning to adopt rationalism as a consistent approach to understanding the world—focus on building a mindset and habits grounded in reason, evidence, and clear thinking. Here’s a practical breakdown:
Start by prioritizing evidence over intuition or tradition. When faced with a question or decision, ask: “What’s the data here? What can I observe or test?” For example, if you’re debating whether coffee improves focus, don’t just lean on how it feels—look at studies on caffeine’s effects or track your own productivity with and without it. This trains you to anchor beliefs in what’s verifiable.
Next, embrace doubt as a tool. Rationalism isn’t about being certain all the time; it’s about questioning assumptions, even your own. If you think “I’m always right about politics,” pause and test that. Have you ever changed your mind? If not, you might be stuck in bias, not reason. Check your reasoning by seeking out opposing views—say, reading a smart critique of your stance—and see if it holds up.
Think probabilistically. Absolutes like “this is true” or “that’s impossible” are rare. Instead, weigh likelihoods: “There’s a 70% chance this diet works based on the evidence.” It’s less sexy than certainty, but it’s more honest and keeps you flexible when new info comes in.
Avoid emotional hijacking. Feelings can cloud judgment—anger might make you dismiss a good argument, or hope might make you cling to a bad one. When you catch yourself getting heated, step back and ask: “What’s the argument, stripped of my mood?” Practice this by debating something low-stakes, like whether pineapple belongs on pizza, and notice how emotions sneak in.
Learn basic logic and fallacies. You don’t need a philosophy degree—just know stuff like “correlation isn’t causation” (e.g., ice cream sales and shark attacks both rise in summer, but one doesn’t cause the other) or “ad hominem” (attacking the person, not the idea). Spotting these in yourself or others sharpens your reasoning.
Finally, test your ideas with small experiments. If you think “meditation boosts my mood,” try it for a week and log how you feel—then skip it and compare. Rationalism thrives on real-world feedback, not just armchair theorizing.
It’s not about being a cold robot—it’s about being deliberate. You’ll still have hunches or passions, but you’ll filter them through a lens of “does this make sense?” Over time, it becomes second nature.
Becoming a rationalist involves cultivating a mindset and a set of skills centered on reasoning, evidence-based thinking, and intellectual honesty. Rationalism, in this context, isn’t about adhering to a strict philosophical doctrine (like the historical Rationalism of Descartes or Leibniz, emphasizing innate knowledge over sensory experience), but rather about adopting a practical, modern approach to reasoning often associated with the contemporary rationalist community—think LessWrong, Bayesian thinking, and figures like Eliezer Yudkowsky or Julia Galef. This guide will walk you through the process of training yourself to think and act as a rationalist, with actionable steps, concepts, and resources grounded in the ethos of clear thinking and skepticism toward untested assumptions.
Step 1: Understand What Rationalism Means Today
Modern rationalism is about optimizing your beliefs and decisions using reason, evidence, and probabilistic thinking. It’s not about being a cold, unfeeling robot—it’s about aligning your thoughts with reality as closely as possible while acknowledging human limitations.
- Core Principles:
- Beliefs should be based on evidence, not tradition or emotion alone.
- Reasoning should be systematic and open to revision.
- Uncertainty is inevitable, and probabilities help manage it.
- Emotions are part of being human, but they shouldn’t override evidence.
- Starting Point: Read The Scout Mindset by Julia Galef (2021). Galef contrasts the “soldier mindset” (defending beliefs) with the “scout mindset” (seeking truth). This is a practical entry into rationalist thinking.
Step 2: Build a Foundation in Critical Thinking
Rationality begins with questioning your assumptions and refining how you process information.
- Key Skills:
- Identify Cognitive Biases: Learn about confirmation bias (favoring evidence that supports your beliefs), availability heuristic (overestimating what’s memorable), and more.
- Resource: Thinking, Fast and Slow by Daniel Kahneman (2011). It’s a deep dive into how System 1 (intuitive) and System 2 (analytical) thinking shape decisions.
- Ask “Why?” and “How do I know this?”: For any belief, trace it back to its evidence. If it’s shaky, suspend judgment.
- Steel Man Arguments: Instead of attacking weak versions of opposing views (straw man), build the strongest case for them to test your own position.
- Exercise: Take a belief you hold (e.g., “Coffee is good for you”). Write down why you believe it, list evidence for and against, and assess its strength. Revise if needed.
Step 3: Master Probabilistic Thinking
Rationalists often use Bayesian reasoning—updating beliefs based on new evidence with probabilities, not absolutes.
- Core Concept: Bayes’ Theorem
- Formula: P(A|B) = [P(B|A) * P(A)] / P(B)
- Translation: The probability of A given B (new evidence) depends on how likely B is given A, your prior belief in A, and the overall likelihood of B.
- Example: If you think there’s a 10% chance it’ll rain (prior), and clouds roll in (evidence), you adjust based on how often clouds mean rain.
- Practical Steps:
- Assign rough probabilities to your beliefs (e.g., “70% chance this project succeeds”).
- Update them when new info arrives (e.g., a key team member quits—adjust to 50%).
- Avoid binary thinking (“It’s true/false”)—reality is rarely 0% or 100%.
- Resource: Rationality: From AI to Zombies by Eliezer Yudkowsky (2015). This is a compilation of LessWrong essays, including a section on Bayes. Start with the online version at lesswrong.com if the book feels daunting.
Step 4: Practice Empirical Testing
Rationalists value evidence over speculation. Test your ideas in the real world.
- Method:
- Form a hypothesis (e.g., “Exercising improves my focus”).
- Design a simple test (e.g., track focus on exercise vs. non-exercise days).
- Collect data and analyze (e.g., “Focus increased 20% on exercise days”).
- Adjust your belief based on results.
- Tool: Keep a notebook or spreadsheet for tracking experiments. Apps like Notion or Obsidian work too.
- Resource: How to Measure Anything by Douglas W. Hubbard (2014). It’s a guide to quantifying the unquantifiable, perfect for empirical rationalists.
Step 5: Engage with the Rationalist Community
Rationality is sharpened through discussion and debate.
- Actions:
- Join LessWrong (lesswrong.com) and read/comment on posts.
- Explore Slate Star Codex (now Astral Codex Ten, astralcodexten.substack.com) by Scott Alexander for nuanced rationalist takes.
- Attend a local rationality meetup (check meetup.com or LessWrong events).
- Why It Helps: You’ll encounter ideas like “double crux” (finding the core disagreement in a debate) and refine your thinking through feedback.
Step 6: Refine Your Decision-Making
Rationalists aim to make choices that maximize expected value, not just short-term gains.
- Framework: Expected Utility
- Calculate: (Probability of Outcome) × (Value of Outcome).
- Example: Job A: 80% chance of $50k = 40k expected value. Job B: 50% chance of $80k = 40k. Dig deeper into risks and intangibles.
- Resource: Algorithms to Live By by Brian Christian and Tom Griffiths (2016). It applies computer science principles (like optimal stopping) to human decisions.
- Exercise: Next time you face a choice (e.g., “Should I move?”), list outcomes, estimate probabilities/values, and pick the highest expected utility.
Step 7: Embrace Intellectual Humility
A true rationalist admits when they’re wrong and updates accordingly.
- Practice:
- Say “I don’t know” when you lack evidence—don’t bluff.
- Celebrate being proven wrong—it means you’ve learned.
- Track your predictions (use PredictionBook.com) to see where you err.
- Quote: “I beseech you, in the bowels of Christ, think it possible you may be mistaken.” — Oliver Cromwell (via Yudkowsky). It’s a rationalist mantra.
Step 8: Make It a Habit
Rationality isn’t a one-off—it’s a lifestyle.
- Daily Routine:
- Morning: Reflect on one belief or decision. Is it evidence-based?
- Day: Test a small hypothesis (e.g., “Skipping coffee affects my mood”).
- Evening: Review what you learned and adjust.
- Long-Term: Revisit this guide monthly. Rationality grows with practice.
Recommended Reading List
- Galef, Julia. The Scout Mindset (2021). ISBN: 978-0735217553.
- Kahneman, Daniel. Thinking, Fast and Slow (2011). ISBN: 978-0374533557.
- Yudkowsky, Eliezer. Rationality: From AI to Zombies (2015). Available free online at lesswrong.com.
- Hubbard, Douglas W. How to Measure Anything (2014). ISBN: 978-1118539279.
- Christian, Brian & Griffiths, Tom. Algorithms to Live By (2016). ISBN: 978-1627790369.
Final Note
Rationality isn’t about perfection—it’s about progress. You’ll still have emotions, biases, and blind spots (we all do). The goal is to catch them, question them, and improve over time. Start small, stay curious, and let evidence guide you. Welcome to the journey!
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