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Non Sequitur

Also Known As: Does Not Follow Irrelevant Conclusion (broad sense)
Formal Fallacy ID: non_sequitur

Definition

Non sequitur (Latin: 'it does not follow') is the broad formal fallacy in which the conclusion does not logically follow from the premises. While many specific fallacies are technically non sequiturs, the term is applied when the logical gap is stark and cannot be classified under a more specific fallacy category. The conclusion may be true or false independently, but the argument provides no valid logical path from premises to conclusion, and the disconnect is too fundamental to be attributed to a missing premise.

Examples

"She's an excellent mathematician, so she'll make a great manager." (Mathematical ability does not entail management ability without substantial additional premises.)

A politician declares: 'I grew up in a small town and know what hard work means. Therefore, my tax policy is the right one for this country.' — Personal background has no logical connection to the correctness of a specific fiscal policy.

An ad campaign claims: 'Nine out of ten dentists recommend brushing twice a day. That's why you should trust our brand of running shoes.' — Dental professional endorsement of a hygiene habit has no bearing on the quality of athletic footwear.

Verification Steps
Verification Steps
Binary yes/no questions that an AI must answer to detect a reasoning pattern in a text.
Each of the 452 aspects has verification steps — simple yes/no questions designed to systematically detect whether a pattern appears in a text. For ad hominem: "Does the argument attack a person rather than their claim?" For false dichotomy: "Are only two options presented when more exist?" This ensures consistent, reproducible analysis.

Binary (yes/no) questions an LLM must answer to identify this aspect:

  1. 1

    Does the argument present premises and draw a conclusion?

    Type: binary
  2. 2

    Is there a logical gap between the premises and the conclusion — does the conclusion not follow from the premises?

    Type: binary
  3. 3

    Is there no unstated premise that could reasonably bridge the gap between premises and conclusion?

    Type: binary
Deep Dive
The expandable detail section on each aspect page with examples, psychology, and counter-strategies.
The Deep Dive section provides in-depth information about each aspect: a real-world example showing the pattern in action, an explanation of why it works psychologically, practical advice on how to counter it, alternative names, and links to related aspects.

Hierarchical Context