Recently, six of my friends and I were talking at our bi-monthly men's group meeting (so now you know how retired men spend their time) and one man, a retired Army colonel with some definite opinions about military and diplomatic misadventures overseas, told us that he was mystified when his 20 year-old son informed him, "Dad, you know jack about what's going on." My friend thought his son had misspoken by leaving out the "don't" here. But he was wrong. His son said it exactly the way he wanted to. The colonel wondered aloud, "how can you say something positive that means a negative?" It happens. Language is a forever changing, creative, dynamic thing and it surprises us all the time with what it is capable of doing. But I had to admit that the positive "know jack" was new to me too. Language Log has dealt with issues of negative polarity and negative by association several times before, especially with expressions such as "care less," "still unpacked," "knows squat," and "cannot be underestimated," for example here and here.
But, as far as I can tell, we haven't dealt with the issue of "he doesn't know jack" versus "he knows jack," which seem to mean the same thing. So I went to my handy Google and typed in "knows jack about" and got over 9,000 hits, most of them conveying a negativity that, at least to my sheltered mind, would seem to need a "doesn't." For example:
So I went back to Google and tried, "doesn't know jack about" and discovered that I was right. It's more commonly used, but not by a whole lot--only by about 4,000 more hits. For example:
Concerning the way "could care less" is conveyed as "couldn't care less," Mark Liberman says that the "not" was added by means of what John Lawler calls negation by association. Similarly, "I could give a damn" becomes "I couldn't give a damn" and "he knows squat" becomes "he doesn't know squat."
So here's another one to add the collection you may or may not know jack about.
UPDATE: Boy, was I wrong here. Several readers have enlightened me about something I never knew--that "jack" stands for "jack shit." I need to get out more. What this seems to mean, as John Cowan so helpfully pointed out, is that "jack" is polysemous, with two senses that are actually very similar but have very different polarity implications: "nothing" and "almost nothing." One has a negative polarity, as in "he knew jack about it," and the other has a positive polarity, a in "he doesn't know jack about it," which means he knows very little. So "jack" can substitute for "anything" in wider scope polarity cases. Miles Townes and Josh Millard suggest that there may also be a politeness feature in the exchange between the son and his father-- a kind of parental respect. All of which goes to show that even 77 year-old fossils like me can keep on learning. Thanks, readers.Posted by Roger Shuy at December 17, 2007 05:24 PM