A principle needs an application bridge
A principle supplies a general standard, often involving what is required, permitted, or prohibited. Applying it requires showing that the case meets its conditions. “Voluntary agreements should be honored unless procured by deception” does not settle a dispute until voluntariness, deception, and the particular obligation are considered.
Distinguish a principle that justifies the conclusion from one that is merely compatible with it. If the conclusion says a proposal must be rejected, a rule saying it may be rejected is too weak to establish that requirement. If the rule concerns public money, facts about privately funded activities may fall outside its scope.
Parallel reasoning keeps the form
A parallel-reasoning exercise asks you to match the structure, not the subject matter. Abstract a passage into relationships: “All A are B; this is A; therefore it is B.” A passage about gardens can match one about scholarships if the logical relationships are the same.
Preserve quantifiers, direction, and strength. “Some,” “all,” “probably,” and “must” are structural features. For parallel-flaw tasks, match the error as well as the outline. A valid argument is not parallel to an invalid reversal just because both use conditional sentences.
Analogies require relevant similarities
An argument from analogy reasons that because cases share some features, they may share another. Its strength depends on the relevance of those shared features to the proposed conclusion. Two institutions having similar logos offers little evidence that the same admission policy will work for both.
A thoughtful comparison identifies both the similarities doing the work and the differences that could defeat the inference. In civic debate, calling a new issue “just like” an old one often conceals the most important work. Say which principle transfers and why the changed circumstances do not defeat it.
Worked example
Any procedure that gives every affected person a meaningful opportunity to respond meets the committee’s participation requirement. This hearing gives every affected person that opportunity. Therefore the hearing meets the requirement.
- General rule
- If a procedure provides the specified opportunity, it satisfies this particular requirement.
- Application premise
- The hearing has that specified feature.
- Conclusion
- The hearing satisfies the participation requirement.
- Scope limit
- Nothing here establishes that the hearing is fair in every other respect or satisfies every other rule.
Check your understanding
Take it into practice
State the rule, establish that the case meets its conditions, and stop at the conclusion that the rule actually licenses.