"Illogical" is vague enough to be useless, and is rarely used in conversation except by Mr Spock. "Non-sequitur" is a very specific form of illogic, appropriate

"Illogical" is vague enough to be useless, and is rarely used in conversation except by Mr Spock. "Non-sequitur" is a very specific form of illogic, appropriate in this case. I'm sorry if there's anyone out there who doesn't understand "non-sequitur" -- admittedly a Latin phrase but one that's fairly well incorporated into the English language. But I really don't think it's obscure, especially by the standards of the kinds of obscure conversations which this site is filled with. For what it's worth, I actually remember where I first learned the term "non-sequitur". It was in Mad Magazine when I was probably eight years old, and I was reading an article about (I think) "Parental Non-Sequiturs". If it's good enough for Mad Magazine, it's good enough for me.