non sequitur

• non-sequitur

From the Latin phrase nōn sequitur (“it does not follow”), from nōn (“not”) + sequitur (third-person form of sequor (“I follow”)); in Latin, the phrase sees no use as a noun. Compare sequence, from same root.

• (Received Pronunciation) IPA^(key): /ˌnɒnˈsɛk.wɪ.tə/
• (US) IPA^(key): /ˌnɑːnˈsɛk.wɪ.tɚ/

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non sequitur (plural non sequiturs or non sequuntur)

1. Any abrupt and inexplicable transition or occurrence.

   Having a costumed superhero abduct the vicar was an utter non sequitur in the novel.

2. Any invalid argument in which the conclusion cannot be logically deduced from the premises; a logical fallacy.
3. A statement that does not logically follow a statement that came before it.
   • 2012 August 5, Nathan Rabin, “TV: Review: THE SIMPSONS (CLASSIC): “I Love Lisa” (season 4, episode 15; originally aired 02/11/1993)”, in (Please provide the book title or journal name)‎:

     Ralph Wiggum is generally employed as a bottomless fount of glorious non sequiturs, but in “I Love Lisa” he stands in for every oblivious chump who ever deluded himself into thinking that with persistence, determination, and a pure heart he can win the girl of his dreams.

4. (humor) A kind of pun that uses a change of word, subject, or meaning to make a joke of the listener’s expectation.

The legitimate plural forms of non sequitur include the Anglicised non sequiturs and the Classical non sequuntur; non sequituri is also attested, but is rare, non-standard, and misformed.

In sense “abrupt transition”, contrast with segue (“move smoothly from one subject to another”), which is etymologically opposite (“does not follow” vs. “follow”). However, segue has connotations of moving between distinct subjects, and thus to segue often means to change rather abruptly, with at best a pretense of smooth transition – in both cases there is often a rapid move between distinct subjects, with the distinction being whether this is done smoothly or not.

• (valid argument): sequitur

• nonsequitous
• non-sequiturial

• apropos of nothing
• deus ex machina
• fallacy
• paradox
• what does that have to do with the price of tea in China
• Wikipedia article on logical fallacies
• Wikipedia article on non sequiturs
• List of types of logical fallacy