When I was growing up, I would always cringe when someone said “I could care less” instead of “I couldn’t care less.” Didn’t they realize they were trying to say that there was no level of care that was lower than theirs and that that is what they were trying to communicate? Didn’t they realize they were wrong in what they said?
Of course, they weren’t wrong. The point of using the expression “I could care less” was to communicate a message to me and it is the same message that is communicated when someone uses the expression “I couldn’t care less”: that the person doesn’t care. I suspect you don’t get confused as to what the underlying message is when you hear either of these expressions is, either.
The problem arises is because we naturally think that languags is logical in nature. We think that introducing a “not” into a sentence will always negate it. For the most part, this heuristic is a good one to follow, but a closer inspection will reveal language for be much more slippery when logic is attempted to be applied.
For example, in the book Grammar Matters: The Social Significance of How We Use Language, Jila Ghomenshi writes about our use of the word “and”. She states that in logic, and merely connects two conjuncts and doesn’t care about order. For instance the expression ‘ “2+2 = 4” AND “4+4=8” ‘ is true because both conjuncts are true and the expression would be true even if the conjuncts were reversed, as in ‘ “4+4=8” AND “2+2=4” ‘. Logically, these two statements are equivalent. Language, however, is not so forgiving. Ghomenshi asks us to consider the two statements:
a) I fell down the stairs and broke my arm.
b) I broke my arm and I fell down the stairs.
If logic were the only thing at play in these statements, we would have to say that they are equivalent, but of course we can see right off the bat why they are not: the order of these two conjuncts implies cause and effect and temporality. That is to say: in “a”, we read that the broken arm is caused by the falling down the stairs, where as in “b” we read the opposite.
Similarly, in Philosophy of Language: A Contemporary Introduction, by William G. Lycan, we are asked to consider the basic logical conditional “if” in what is called an “invited inference”. Lycan states that if someone utters:
a) If you mow my lawn, I’ll give you ten dollars.
what they really mean is:
b) If and ONLY IF you mow my lawn, I’ll give you ten dollars.
If someone utters “a” it is logically possible that the speaker will give you ten dollars regardless of whether or not we mow the lawn. However, through the use of language, we know that that the speak will only give us the ten dollars if we do mow the lawn – the “only if” is implied (and humans INSTANTLY know this, without thinking about it).
These two examples are meant to scratch the surface of a fact: that language is not constrained by logic. The point (or a point) of language is to communicate a message, and as in the case of “I could care less” the message can be immediately obvious even if the form is, logically or otherwise, jarring.