logical-reasoning
Deductive and inductive reasoning, formal and informal logical structure, validity, soundness, and rules of inference. Covers propositional logic, quantified reasoning, syllogisms, common inference patterns (modus ponens, modus tollens, hypothetical syllogism, disjunctive syllogism), and the distinction between deductive certainty and inductive probability. Use when the question is not whether a premise is true but whether the reasoning from premises to conclusion is logically valid.
npx skills add majiayu000/claude-skill-registry --skill logical-reasoning --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Logical Reasoning Logic is the study of what follows from what. A valid logical argument has a form that preserves truth — if the premises are true, the conclusion cannot be false. This skill covers the core machinery of deductive and inductive reasoning: the rules of inference, the standard argument forms, the common errors, and the boundary between the two styles of reasoning. **Agent affinity:** paul (chair-level framing), elder (inference-pattern drills), tversky (inductive strength) **Concept IDs:** crit-deductive-reasoning, crit-inductive-reasoning, crit-argument-structure ## The Reasoning Toolbox at a Glance | # | Pattern | Form | Type | |---|---|---|---| | 1 | Modus ponens | If P then Q; P; therefore Q | Deductive, valid | | 2 | Modus tollens | If P then Q; not Q; therefore not P | Deductive, valid | | 3 | Hypothetical syllogism | If P then Q; if Q then R; therefore if P then R | Deductive, valid | | 4 | Disjunctive syllogism | P or Q; not P; therefore Q | Deductive, valid | | 5 | Constructive dilemma | (P or Q); (if P then R); (if Q then S); therefore (R or S) | Deductive, valid | | 6 | Universal instantiation | All A are B; x is an A; therefore x is a B | Deductive, val
- The Reasoning Toolbox at a Glance
- Deductive Reasoning: Form Preserves Truth
- Pattern 1 — Modus Ponens
- Pattern 2 — Modus Tollens
- Pattern 3 — Hypothetical Syllogism (Chain Rule)
- Pattern 4 — Disjunctive Syllogism
- Pattern 5 — Constructive Dilemma
- Pattern 6 — Universal Instantiation
- Pattern 7 — Existential Generalization
- Invalid Deductive Forms (Formal Fallacies)
- Fallacy 8 — Affirming the Consequent
- Fallacy 9 — Denying the Antecedent
- Inductive Reasoning: Probability, Not Certainty
- Pattern 10 — Enumerative Induction
What does the logical-reasoning skill do?
Deductive and inductive reasoning, formal and informal logical structure, validity, soundness, and rules of inference. Covers propositional logic, quantified reasoning, syllogisms, common inference patterns (modus ponens, modus tollens, hypothetical syllogism, disjunctive syllogism), and the distinction between deductive certainty and inductive probability. Use when the question is not whether a premise is true but whether the reasoning from premises to conclusion is logically valid.
How do I install it?
Run `npx skills add majiayu000/claude-skill-registry --skill logical-reasoning --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From majiayu000/claude-skill-registry, a repository with 534 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.