Say you're acquainted with someone, you see each other around and give a nod or a hello. This is an acquaintance not a friend. You don't know much about the person.
To say "I know you" can be both true and false. Just as saying "I don't know you" can be both true or false. Depending on context and circumstances and how much 'know' the person means, the truth of the statement can change. It's an ambivalent language that can have multiple meanings.
Here is a different example(This may be something else entirely):
Say that your partner is being unfaithful to you but they go to a hotel. You're sure that this is happening and accuse them of having extra marital affairs at home. The person says "Baby oh baby, I haven't had anyone over, I swear it" in order to evade accountability, a break up or whatever else the reason. It's a true statement, but it's also false. It isn't overtly a lie, it's a lie by omission.
Is there a name for this kind of language? Always in flux, never delivers solid information, and can have different meanings from different angles.