A non sequitur is a statement or conclusion that does not logically follow from what came before it. The phrase is Latin for “it does not follow.” In reasoning, it is a logical fallacy. In conversation and comedy, it can be a deliberate leap for surprise or humor.
Two common uses
- Logical error
An argument where the conclusion is not supported by the premises. - Conversational jump
A reply that switches topics without a link, often for comedic effect.
How non sequiturs happen
- Missing links in the chain of reasoning
- Hidden or false assumptions
- Confusing correlation with causation
- Category mistakes and invalid inference forms
Quick test for spotting one
Ask: If the premise is true, must the conclusion be true. If the answer is no, you likely have a non sequitur.
Clear examples with fixes
- Affirming the consequent
Premise: If it rains, the streets get wet.
Observation: The streets are wet.
Conclusion: Therefore it rained.
Why it fails: Sprinklers or street washing could also wet streets.
Better: The streets are wet, which is consistent with rain, but other causes are possible. - Undistributed middle
Premise: All cats are mammals.
Premise: Fido is a mammal.
Conclusion: Fido is a cat.
Why it fails: Being a mammal does not imply being a cat.
Better: Fido is a mammal, but we need more information to classify the species. - Post hoc or causation jump
Statement: Sales rose after we changed the logo, so the logo caused the rise.
Why it fails: Many factors could raise sales.
Better: Test the logo change against controls and trends before claiming causation. - Scope shift
Statement: One employee lied, so the whole company is dishonest.
Why it fails: A single instance does not justify a universal claim.
Better: Investigate whether the behavior is systemic. - Topic switch in meetings
Problem: Users cannot find the checkout button.
Reply: Make the logo bigger.
Why it fails: The suggestion does not address discoverability of checkout.
Better: Improve button placement, labeling, or flow. - Stereotype jump
Statement: She is from a big city, so she must hate small towns.
Why it fails: Residence does not determine preference.
Better: Ask for her preferences. - Overgeneralization in math
Observation: 2 and 3 are prime.
Conclusion: All odd numbers are prime.
Why it fails: 9 and 15 are counterexamples.
Better: Form a testable hypothesis and check against data. - Conversational non sequitur
A: Do you want tea.
B: The moon is bright tonight.
Use: Humor or surreal tone, not reasoning. - Advertising leap
Claim: This car has leather seats, therefore people will respect you.
Why it fails: Features do not guarantee social status.
Better: Show measurable benefits such as durability or comfort. - Online debate shortcut
Statement: You disagree with my policy, so you hate progress.
Why it fails: Disagreement can come from different definitions or tradeoffs.
Better: Clarify goals and evidence before judging motives.
How to avoid making non sequiturs
- Keep the claim within the support your evidence provides.
- State assumptions and check whether they are shared.
- Trace the chain from premise to conclusion step by step.
- Look for alternative explanations and test them.
- Use clear definitions and the same scope throughout an argument.
Why they can be persuasive
Non sequiturs feel convincing when the jump matches our biases or when a vivid image fills in the missing link. They also work in humor because the unexpected shift creates surprise. Good thinkers enjoy the joke but do not mistake it for proof.
Bottom line
A non sequitur is any leap where the conclusion does not follow from the premise. Learn to spot the jump, supply the missing links, and keep claims no stronger than the evidence allows.
