"I don't disagree."
What?
That's a doozy. If the person does, 'not disagree', doesn't that person agree? Or, apparently, the person does disagree. Why use an expression that is purposefully meaningless, self contradictory, and downright confusing?
The statement can have only one of three meanings:
- Agreement
- Disagreement
- Agree with some parts and disagree with other parts of the presenter's view
A person cannot 'kind of agree'. The speaker either does or doesn't agree. If the person agrees with some of what you said and disagrees with other elements, that is not "not disagree" it is agreeing with some elements and not with others.
If a person agrees with you and is using this expression, the speaker is either: