deductive-reasoning

name	deductive-reasoning
description	Use when a conclusion must be tested against explicit rules, principles, criteria, policies, definitions, premises, or if-then logic. Use when applying deductive reasoning, rule-based reasoning, premise-to-conclusion testing, logical consistency checks, or validity review.
license	Apache-2.0

Deductive Reasoning

Use this skill to test whether a conclusion follows from stated premises, rules, or criteria.

Method Notes

• Deductive reasoning moves from general rules or premises to a specific conclusion.
• A deductive conclusion is only as reliable as the premises and the logic connecting them.
• This method is strongest when rules, definitions, criteria, or constraints are explicit.
• It should separate validity from truth: an argument can be logically valid but built on a false or weak premise.

Required Inputs

Collect or infer these inputs before execution:

• conclusion or decision to test
• stated rules, criteria, principles, policies, or premises
• facts of the specific case
• scope boundary
• exceptions or override conditions

If an input is missing, mark it as missing, state the assumption used, and add a validation action.

When Not To Use

Do not use when there are no clear premises or rules and the task is pattern discovery. Use inductive-reasoning, abductive-reasoning, or affinity-diagram first.

Step-by-Step Execution

Step	Required input	How to execute	Output
State the conclusion	Decision, claim, or recommendation.	Write the conclusion in one testable sentence.	Conclusion to test.
List premises	Rules, criteria, policies, principles, definitions.	Separate general premises from case-specific facts.	Premise list.
Check premise quality	Source, evidence, authority, scope.	Mark each premise as strong, medium, weak, or missing.	Premise quality table.
Map logic chain	Premises, case facts, conclusion.	Build the if-then path from premises to conclusion.	Logic chain.
Test validity	Logic chain, exceptions.	Check whether the conclusion necessarily follows if premises are true.	Validity judgment.
Check exceptions	Scope, edge cases, override conditions.	Identify conditions that weaken or reverse the conclusion.	Exception list.
Rewrite conclusion	Validity and premise quality.	State a careful conclusion that matches the actual logic strength.	Revised conclusion.

Output Template

### 1. Conclusion To Test
- Claim / decision:
- Scope:

### 2. Premise Table
| Premise | Type | Evidence / source | Strength | Scope limit |
|---|---|---|---|---|
|  | rule / criterion / principle / fact / assumption |  | strong / medium / weak / missing |  |

### 3. Logic Chain
1.
2.
3.

### 4. Validity Check
- Does the conclusion follow if the premises are true?
- Weakest premise:
- Exception or edge case:
- Revised conclusion:

Quality Gate

• Do not treat an assumption as a rule.
• Do not hide weak premises inside confident logic.
• Separate logical validity from real-world truth.
• Identify exceptions and scope limits.
• Use plain wording so the conclusion can be challenged or reused.