Dear Word Detective: Over the years I have frequently puzzled over the origin and actual meaning (if any) of the interjection “why,” as in “Why, you dirty, rotten, no good….” The noun and adverb seem obviously related, but the interjection does not. Why “why?” When I was about 20, I had a buddy, Al, with whom I would get into long, detailed, abstract conversations exploring utter nonsense at great length (mostly while drinking coffee at the Waffle House). One evening, I made a particularly penetrating metaphysical conjecture, asking “why is so and so?” Al, quick to trivialize my question, said, “Why not?” That frustrated me and my inquiry. Demanding to know why his question was better than mine, I blurted, “Why ‘Why not?’, why not ‘Why?’?” Our discussions were always pretty deep; usually about knee deep. — Phil.
Wow. You drank the coffee at Waffle House? I’m surprised you both didn’t end up asking, “Why am I crawling across the parking lot in horrible pain?” Just kidding. I actually like Waffle House, especially their cheese-smothered hash browns. And the world needs cheap restaurants that are open all night.
“Why” is a remarkable little word. It might well be the quintessential “human” word, expressing as it does the search for the reasons things happen, an activity usually associated with people rather than our animal companions. Of course, there are indications that many animals reason far more than once thought (and some humans considerably less), but human progress, such as it is, has largely been due to our reluctance to accept “because” as an answer.
Given that one of the first questions humans asked was something like “Why is that pterodactyl staring at me?”, it’s not surprising that “why” is a very old word, derived from the Indo-European root “quo,” which also gave us the useful “what” and “who.” As an adverb, “why” is used to introduce a question (“Why did you leave?”) or, in various forms, to refer to either a question or an answer (“If I told you why, you’d hate me”). “Why?” and “Why not?” are abbreviated uses of this adverbial form, with the remainder of the question omitted because it is obvious from the context (“Should I go?” “Why not?”). As a noun, “why” can refer to either a question or an answer (“The region not of life’s how, but of life’s why,” 1907).
“Why” is used as an interjection in two ways: as an expression of surprise, often with overtones of disagreement or protest (“Why, I’m as patriotic as anyone”), or expressing emphasis (“Of course you should go. Why, I’ll drive you myself”). These uses of “why” are of fairly recent vintage, dating to the 16th century. The form “Why, you dirty, rotten, no good….” expresses both surprise and emphasizes the statement that follows (e.g., “… I oughta punch you in the snout”).
This use of “why” as an interjection is purely idiomatic; it really doesn’t involve “why” as the prelude to a question, and there’s no way to trace the logic, if any, of this use. It doesn’t make sense, but many usages in English don’t. It’s just the way we’ve used the word since the 1500s, which makes it established English usage. So, at this late date, the answer to “Why ‘why’?” is simply “Why not?”