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From skills-for-humanity
Validates whether an argument's premises support its conclusion and identifies logical fallacies. Use for reviewing design decisions, technical proposals, or any reasoning chain.
npx claudepluginhub human-avatar/skills-for-humanityHow this skill is triggered — by the user, by Claude, or both
Slash command
/skills-for-humanity:s4h-logic-argument-validationThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
An argument can *sound* compelling while the reasoning is broken. Confident language, plausible premises, a conclusion that feels right — none of these guarantee the argument actually holds. This skill validates the structure: do the premises support the conclusion, and is the reasoning free of fallacies?
Produces a complete logic report on any argument, plan, or reasoning — validates premises, tests inference, detects fallacies, and surfaces hidden assumptions.
Analyzes claims by mapping arguments, auditing evidence quality, detecting logical fallacies and biases, and issuing verdicts. For evaluating research or technical arguments.
Construct well-structured arguments using the hypothesis-argument-example triad. Use for PR descriptions, ADRs, code review feedback, and technical proposals.
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An argument can sound compelling while the reasoning is broken. Confident language, plausible premises, a conclusion that feels right — none of these guarantee the argument actually holds. This skill validates the structure: do the premises support the conclusion, and is the reasoning free of fallacies?
Step 1: Extract the argument structure Before evaluating, make the argument explicit:
Restate this clearly before proceeding. Often the weakest point becomes obvious once the structure is explicit.
Framing check: Confirm the argument being examined and the claim at stake before continuing. State what you've identified — the actual argument and the conclusion it is trying to establish — in one sentence, then use AskUserQuestion:
Step 2: Test premise soundness For each premise:
Step 3: Test the inference Does the conclusion actually follow from the premises, even if the premises are true? Common inference failures:
Step 4: Check for fallacies Scan for common fallacies. Name them specifically if found:
| Fallacy | What it looks like |
|---|---|
| Ad hominem | Attacking the source rather than the argument |
| Straw man | Misrepresenting a position to make it easier to refute |
| False dichotomy | Presenting two options when more exist |
| Circular reasoning | The conclusion is smuggled into the premises |
| Slippery slope | Assuming a chain of consequences without justifying each step |
| Appeal to authority | Citing authority as a substitute for evidence |
| Hasty generalisation | Drawing broad conclusions from insufficient cases |
| Post hoc | Assuming causation from correlation or sequence |
| Equivocation | Using the same word in two different senses |
Step 5: Verdict
Before proceeding, use the AskUserQuestion tool. State your interpretation of the situation in 1–2 sentences — what is being analyzed and what the core question is — then ask:
Proceed based on their selection. If the user reframes, incorporate the correction before running any analysis.
Argument: [Premises / Conclusion restated explicitly]
Premise Assessment
| Premise | Status | Issue |
|---|---|---|
| [premise] | ✅ Established / ⚠️ Assumed / ❌ Contested | [note] |
Inference Assessment [Does the conclusion follow? Where does the chain hold or break?]
Fallacies Detected
Verdict [Does the argument hold? What is the specific weakest point?]
What would strengthen it
A broken argument isn't necessarily a wrong conclusion. The conclusion might be correct while the reasoning that supports it is flawed. Flag both: the structural problem and whether the conclusion still seems defensible by other means.
After delivering this output, use AskUserQuestion to offer the next move:
/s4h-logic-fixer — Repair the invalid inferences found/s4h-ethics-check — Check whether a valid argument is also ethically sound/s4h-communication-objection-mapping — Map how others will challenge this argument