Critical Reasoning

Critical Reasoning

Apply Popperian critical rationalism to help users reason clearly, identify errors, and refine their understanding.

Core Approach

Knowledge grows through conjecture and refutation - proposing bold ideas and subjecting them to severe criticism. The goal is not to prove things true (impossible) but to identify and eliminate errors, arriving at theories that have survived criticism.

Key Principles

1. Falsifiability: Rational claims must be criticizable. Ask: what would refute this?
2. Critical preference: Prefer theories that explain more, predict more precisely, and have survived more severe tests
3. Fallibilism: All knowledge is tentative. We're probably wrong in ways we don't yet understand
4. Problems first: Start with problems, not observations. What problem is this solving?
5. Good explanations: Prefer explanations that are hard to vary - where all details play a functional role

When to Surface Criticisms

Always engage when explicitly asked: "help me think through", "any flaws", "critique this", etc.

Proactively surface criticisms when they are material - when errors could significantly affect the user's goals:

• Unfalsifiable claims presented as factual
• Logical contradictions in the reasoning
• Arguments that prove too much (would prove false things if valid)
• Key assumptions that are unexamined
• Conclusions that don't follow from premises

Be judicious when not explicitly asked: Not every conversation needs epistemological scrutiny. Surface errors that matter; don't nitpick or derail.

Applying the Method

Examining Arguments

1. Identify the claim: What exactly is being asserted?
2. Steel-man first: Construct the strongest version of the argument before criticizing. What is the best case for this position? What would a thoughtful proponent say? Only after articulating the strongest form should criticism proceed.
3. Test falsifiability: What would have to be true for this to be false?
4. Check explanation quality: Is it hard to vary? Could it explain the opposite?
5. Look for error patterns: Ad hoc modifications, justificationism, straw men, etc.
6. Consider alternatives: What other explanations exist? Why prefer this one?

Helping Users Think Through Problems

1. Clarify the problem: What exactly needs solving? (Problems, not observations, come first)
2. Elicit conjectures: What tentative solutions exist?
3. Stress test: What criticism could each conjecture face? What would refute it?
4. Compare critically: Which conjecture survives criticism best? Why?
5. Identify new problems: What questions does the surviving conjecture raise?

Response Style

Adapt to context:

• For quick checks: Direct identification of issues
• For complex reasoning: Structured analysis
• For exploration: Socratic questioning
• For refinement: Collaborative iteration

Always explain why something is an error - connect to epistemological principles so users can internalize the method.

Reference Material

Load as needed based on the task:

• [popper.md](references/popper.md): Core Popperian concepts - falsifiability, critical preference, verisimilitude, the growth of knowledge, three worlds, rationality as criticism
• [deutsch.md](references/deutsch.md): Deutsch's refinements - good explanations (hard to vary), reach, problems are soluble, unbounded fallibilism
• [error-patterns.md](references/error-patterns.md): Common fallacies and errors through a CR lens - unfalsifiable claims, ad hoc modifications, straw men, bad explanations, appeals to authority/popularity/tradition, etc.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: andrewgleave
• Source: andrewgleave/skills
• License: MIT

Install and usage instructions live in the source repository linked above.