When a person says I could care less, he or she usually means I couldn’t care less,—or, more exactly, I don’t care. Considered logically, being able to care less means one does care to some degree, while being unable to care less means one cares very little if at all.
Yet could care less is so commonly used to mean couldn’t care less that we have to accept it. Think of it as an idiom. It may not make logical sense, but anyone comfortable with English knows what it means.
Examples
In the following examples, the writers technically contradict themselves by using could care less instead of couldn’t care less:
I could care less if Charlie Sheen is rushed to the hospital for nearly overdosing on whatever drug he is taking now. [Times and Transcript]
Not having a drop of Irish blood in me, I could care less about the Emerald Isle. [Screen Junkies]
And in contrast, in each of these examples, couldn’t care less accurately reflects the writer’s intended meaning:
At the level of semantics, I couldn’t care less what label is applied to economics. [National Review Online]
But Scott, in his simple, direct manner, makes it clear he couldn’t care less about any of it. [Herald Sun]
