critical-thinking

A reasoning guide for examining hard questions, claims, evidence, uncertainty, and decisions. It provides structured checks for spotting errors, testing assumptions, and considering alternatives.

In plain words
What is it for?
Use it to analyze arguments or statistics, estimate odds, diagnose recurring failures, challenge plans, brainstorm options, and make decisions under uncertainty.
Why use it?
It helps reduce snap judgments and makes uncertainty and weak evidence easier to notice. This is useful when the right answer is not obvious or the consequences matter.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/johna2an/critical-thinking/skill
Any agent
npx skills add Johna2an/critical-thinking --skill skill
Clone the repo
git clone --depth 1 https://github.com/Johna2an/critical-thinking

Made for: Claude Code, Codex.

Per session 480 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,668 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00480 $0.04668
Opus 5 $0.00240 $0.02334
Sonnet 5 $0.00096 $0.00934
Haiku 4.5 $0.00048 $0.00467

Measured 2d ago against content hash dbfcc254d216, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

critical-thinking scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skill/SKILL.md · 280 lines

How it starts

The opening of the file, as written. The whole thing — 280 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Think clearly and decide well. The first answer your mind offers is a hypothesis, not a verdict. This skill is a toolkit for catching your own errors, reasoning cleanly, quantifying uncertainty, stress-testing claims, thinking in systems, generating real alternatives, and deciding under uncertainty. It carries the working tools of 51 books on judgment, creativity, systems, uncertainty, models, and the philosophy of science. The directives below are the operating manual; references/ holds the deep tool libraries and a per-book teaching library.

How to use this

Apply the phases that fit the task. Phase 1 (frame) and Phase 2 (check yourself) run on almost every hard question; the rest engage as the problem demands. Load a reference file only when the task needs that depth, and load a per-book file only when a task calls for that book. Read only what the task needs. When two directives seem to conflict, scope to purpose (see "When the directives collide").

Phase 1. Frame the question

  • State the exact question. Pin the issue and the conclusion in plain words before reacting. Sort the issue: is it descriptive (what is) or prescriptive (what ought)? The two need different evidence.
  • Catch the swap. Ask what you were actually asked and what easier question your mind answered instead. A hard call that suddenly feels easy and emotionally clear is a substitution (attribute substitution).
  • Set the boundary on purpose. Decide what is inside the frame and what is out, then deliberately pull back in the delayed effects, distant people, and long-term consequences you first excluded.

Phase 2. Check yourself (bias and the scout stance)

  • Ask "Is it true?" rather than "Can I believe it?" or "Must I believe it?" Notice which question you were running. You bend evidence toward what you want and away from what you resist, so flip the standard and re-check.
  • Hold beliefs as probabilities and your identity lightly. State a number rather than a certainty, and arrange things so being wrong costs you nothing. A belief welded to your identity gets defended instead of tested, so hold it lightly.
  • Run the selective-skeptic test. If this same evidence pointed the other way, would you still find it credible? A different standard for friendly and unfriendly evidence is a double standard.
  • Hunt disconfirming evidence first. Record every fact that cuts against you the instant you meet it, because the mind drops inconvenient facts faster than convenient ones. Lean into confusion rather than explaining it away.

Read the full file on GitHub · 280 lines

Files

What ships with it

60 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 280 lines · 480 tokens per session scan A dbfcc254d216

Subscribe to this mod's changes

critical-thinking is a skill published in the GitHub repository Johna2an/critical-thinking (5 stars, last pushed 2mo ago), licensed MIT. It adds 480 tokens to every session and 4,668 once invoked, about $0.0024 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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