Time Flies Like an Arrow; Fruit Flies Like a Banana

Groucho Marx? Anthony Oettinger?

Dear Quote Investigator: My favorite quote attributed to Groucho Marx is the absurdist, “Time flies like an arrow. Fruit flies like a banana.” But I have read enough of this blog to know that sometimes quotes are wrongly credited. Can you tell me about this quote?

Quote Investigator: Yes, but the news is not good for your favorite Groucho quote. The Yale Book of Quotations is a wonderful reference that I recommend to all readers of this blog. Editor Fred R. Shapiro has researched this quote and says “There is no reason to believe that Groucho actually said this. It appeared in the Usenet news group net.jokes, 9 July 1982.”

So where did this quote come from?

QI has traced the core of the quotation to the work of an early researcher in artificial intelligence, Anthony Oettinger, who was trying to get a computer to manipulate the English language. In the magazine Scientific American in 1966, Oettinger describes a computer program that takes sentences as input and attempts to determine which words are acting as verbs, nouns, adjectives, and adverbs, etcetera [OET]. The example input he uses is “Time flies like an arrow”, but the task is complicated because the computer program must also work properly for sentences such as “Fruit flies like a banana” and “Time runners with a stop-watch”. Here is what he says:

A grammar that pretends to describe English at all accurately must yield a structure for “Time flies like an arrow” in which “time” is the subject of the verb “flies” and “like an arrow” is an adverbial phrase modifying the verb. “Time” can also serve attributively, however, as in “time bomb,” and “flies” of course can serve as a noun. Together with “like” interpreted as a verb, this yields a structure that becomes obvious only if one thinks of a kind of flies called “time flies,” which happen to like an arrow, perhaps as a meal. Moreover, “time” as an imperative verb with “flies” as a noun also yields a structure that makes sense as an order to someone to take out his stopwatch and time flies with great dispatch, or like an arrow.

Oettinger says it is possible to modify his computer program to rule out the possibilities that seem unlikely, but this is problematic because the program may then fail to generate the proper results for other related sentences:

Worse yet anything ruling out the nonexisting species of time flies will also rule out the identical but legitimate structure of “Fruit flies like a banana.”

A popular text in artificial intelligence mentioned this work and contained the two sentences: “Time flies like an arrow” and “Fruit flies like a banana” [AI]. A generation of researchers in artificial intelligence, machine translation, and computational linguistics were exposed to them. ┬áBy 1982 or before someone juxtaposed the sentences to yield a funny combination which was then assigned to Groucho Marx. Marx died in 1977 so it is possible that he said the words but there is no direct evidence of this.

[OET] 1966 September, Scientific American, The Uses of Computers in Science by Anthony Oettinger, Page 168, Volume 215, New York. (Verified on paper)

[AI] 1970, Human and Artificial Intelligence edited by Frederick J. Crosson, Introduction, Page 15, Meredith Corporation, New York. (Google Books snippet view, Verified on paper) link