Q: I came across a startling idiom while living in southern Missouri. If I asked someone a favor, the response would be “I don’t care,” but the meaning would be “I’m willing.” Can you help clarify?
A: What you heard in Missouri is an American regionalism that dates from the early 20th century, but it has roots in a usage that showed up in England in the 1500s.
To begin at the beginning, the verb “care” has meant, among other things, to be concerned about something since it appeared in Old English.
The earliest example in the Oxford English Dictionary is from Beowulf, an epic poem that may date from as early as 700: “Na ymb his lif cearað” (“Nor cares about his life”).
We still use the verb “care” that way. The latest OED example is from Play Therapy, a1947 book by the psychologist Virginia Mae Axline: “Fall on the floor, damn you! See if I care.”
In the early 16th century, the verb in negative constructions took on a sense similar to the one you’re asking about.
“Not to care,” according to the OED, came to mean “not to mind (something proposed); to have no disinclination or objection, be disposed to.”
The dictionary’s first citation is from Pylgrimage of Perfection, a 1526 treatise by the English monk William Bonde: “Some for a fewe tythes, with Cayn, careth nat to lese the eternall ryches of heuen.”
The OED adds that when the usage is seen now “care” is accompanied by the preposition “if” or “though.” However, the dictionary’s most recent citation is from the mid-19th century.
Here’s an “if” example from Shakespeare’s Henry IV, Part 2 (1600): “I care not if I doe become your phisitian.”
And here’s one from Clarissa, a 1748 novel by Samuel Richardson: “Will you eat, or drink, friend? … I don’t care if I do.”
As for the usage you heard in Missouri, the Dictionary of American Regional English says the verb “care” is used in the negative to mean “to be willing, to be pleased,” usually “in response to an invitation.”
So in this sense, “I don’t care to” would mean “I’m willing to” or “I’d be pleased to” or simply “Yes.”
DARE identifies this as a regionalism of the Midlands section of the country. Here are the examples on record, with the locations listed first.
Southern Indiana: “People might think you were brash if you answered straight out ‘Yes’ to an offer of food or drink, so to be polite you said ‘I don’t care.’ ” (From 1980 DARE records of a usage current “as of c1900.”)
Southeast Missouri: “Care…. In negative ‘not to care’; a common expression denoting consent. ‘Will you go to dinner with me?’ ‘I don’t care.’ (Not meant to be indifferent.)” (From the journal Dialect Notes, 1903.)
Northwest Arkansas, southeast Missouri, southeast Kentucky: “Care (with negative)…. To be willing. ‘If I had a horse and carriage I wouldn’t care to take you to Boring.’ ” (From Dialect Notes, 1907.)
Central Kentucky: “I hope to live my life out so people won’t care to look at me, and I won’t care to meet nobody…. You don’t have to be hateful. You can be kind. And people don’t care to look at you.” (From Ellesa Clay High’s Collection of Terms Recorded in the Red River Gorge, 1981, describing a usage current “as of c1930.”)
West Virginia mountains: “ ‘Come and set?’ ‘I wouldn’t keer to.’ The rising inflection of the guest’s voice indicated her willingness, so together they dropped down in the cool grass.” (From Alberta Hannum’s novel Thursday April, 1931.)
Western North Carolina, eastern Tennessee: “ ‘She don’t care to talk’ [means] she doesn’t mind talking, i.e. she is a great talker.” (From the Joseph Sargent Hall collection of dialect materials, 1937.)
West Virginia: “One of the most baffling expressions our people use … is ‘I don’t care to….’ To outlanders this seems to mean a definite ‘no,’ whereas in truth it actually means, ‘thank you so much, I’d love to.’ ” (From West Virginia History, 1969, at the state Department of Archives and History.)
And this is an example from much farther north: “Maine Circumlocutions … such as, ‘I don’t care for him’ when the meaning is, ‘I have no objection to him.’ ” (From Down East: The Magazine of Maine, 1971.)
The verb “mind” has been used similarly in negative constructions to mean “to care, trouble oneself,” according to the OED.
Here’s an example from Foreign Parts, a 1994 novel by Janine Galloway: “We can sit here for a while if you like. Whatever, Cassie said. I don’t mind. Whatever.”
Finally, we have the negative use of “mind” in the expression “I don’t mind if I do,” which the OED defines as “a humorous circumlocution accepting an invitation, esp. the offer of a (usually alcoholic) drink.”
The dictionary’s earliest example is from The Round of Wrong, an 1847 play by William Bayle Bernard: “Reu. You’ll have some tea? Duc. Well, I don’t mind if I do.”
And this is alcoholic example is from Charlotte Brontë’s 1849 novel Shirley: “ ‘Take another glass,’ urged Moore. Mr. Sykes didn’t mind if he did.”
from Grammarphobia http://www.grammarphobia.com/blog/2016/03/i-dont-care.html