logical-fallacies

logical-fallacies is a skill for Claude Code, Codex from deciqAI/knowledge-skills. It costs 104 tokens per session (2,172 once invoked), scanned A, original, MIT.

A guide to spotting arguments that look convincing but contain faulty reasoning. It covers errors such as relying on popularity, authority, emotion, or a misleading analogy.

In plain words
What is it for?
It helps check claims, debates, proposals, and decisions for invalid conclusions, unsupported assumptions, and misleading persuasion.
Why use it?
It makes it easier to explain why an argument is weak instead of accepting it because it sounds persuasive.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It helps check claims, debates, proposals, and decisions for invalid conclusions, unsupported assumptions, and misleading persuasion.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/deciqai/knowledge-skills/logical-fallacies
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.

Any agent
npx skills add deciqAI/knowledge-skills --skill logical-fallacies
Clone the repo
git clone --depth 1 https://github.com/deciqAI/knowledge-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for logical-fallacies

README.md
[![agentmods](https://agentmods.dev/badge/skills/deciqai/knowledge-skills/logical-fallacies/github.svg)](https://agentmods.dev/skills/deciqai/knowledge-skills/logical-fallacies)
Your own site
<a href="https://agentmods.dev/skills/deciqai/knowledge-skills/logical-fallacies"><img src="https://agentmods.dev/badge/skills/deciqai/knowledge-skills/logical-fallacies/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for logical-fallacies

Your own site · 80×15
<a href="https://agentmods.dev/skills/deciqai/knowledge-skills/logical-fallacies"><img src="https://agentmods.dev/badge/skills/deciqai/knowledge-skills/logical-fallacies.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 104 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,172 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00104 $0.02172
Opus 5 $0.00052 $0.01086
Sonnet 5 $0.00021 $0.00434
Haiku 4.5 $0.00010 $0.00217

Measured 9d ago against content hash 90d635af9c64, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

logical-fallacies 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 9d 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.

logical-fallacies/SKILL.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Logical Fallacies

Overview

A fallacy is an argument that looks like it works but doesn't. The test is not whether the conclusion is true — it's whether the inference from premises to conclusion is valid. This skill covers two layers: the classical taxonomy (Aristotle's 13, c. 350 BCE — verbal and structural errors) and the modern cognitive map (Tversky-Kahneman 1983 — errors competent reasoners commit automatically before any sophist arrives).

Composes with neighbors: critical-thinking audits evidence quality and framing; first-principles attacks premises; mece catches decomposition errors that masquerade as false-dichotomy or composition fallacies.

When to Use

  • An argument feels persuasive but you cannot articulate why
  • A claim is supported entirely by authority, popularity, emotion, or anecdote
  • You're about to decide based on a single argument or analogy
  • A debate is moving fast ("everyone knows Y") — speed is the sophist's friend
  • You catch yourself reasoning emotionally ("this has to be true because…")
  • You're weighing an AI hype or AI-adoption claim ("a lab CEO said it's near," "it passed the benchmark so it's intelligent," "doom vs. utopia")

When NOT to use: casual small talk with low stakes; conclusion is empirically verifiable (just check the data); you're tempted to name a fallacy to dismiss an opponent rather than find truth (that is itself the fallacy fallacy).

Coaching Novices (Adaptive Front Door)

  • Engine mode: user has a concrete argument → run The Process directly.
  • Coach mode: user signals unfamiliarity or has no concrete case → guide step by step.

In Coach mode, respond one step at a time. Each [WAIT] is a hard stop — output only that step's question, then stop.

  1. One-line what-it-is: some arguments sound right but don't earn their conclusion — this is a checklist for finding that gap, including in your own thinking.
  2. Check fit against When to Use / When NOT to use. If data can answer it, say so.
  3. Elicit their real argument — ask for a concrete case (something someone said, an article they're suspicious of). > [WAIT — do not advance until user responds]
  4. Walk through the Audit one pass per turn: pose the question, wait for their answer, surface what they missed. > [WAIT — do not advance until user responds]
  5. Close by naming the one fallacy they found and what changes about the conclusion now that they've seen it. > [WAIT — do not advance until user responds]

Read the full file on GitHub · 119 lines

Files

What ships with it

3 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. 9d ago First seen · 119 lines · 104 tokens per session scan A 90d635af9c64

Subscribe to this mod's changes

logical-fallacies is a skill published in the GitHub repository deciqAI/knowledge-skills (10 stars, last pushed 10d ago), licensed MIT. It adds 104 tokens to every session and 2,172 once invoked, about $0.0005 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 2026-09-03.

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