We understand understanding (according to N. Luhmann) as the aspect of communication, which follows the conveyed information. Understanding links to that which has been said, no matter how: rejecting, agreeing, changing subject, being critical, being pleased, differentiating and so on. Only if the conveyed information falls into a void, does no understanding take place and, with it, no communication either.
Thus, understanding leads to one’s own information. Always. One cannot understand the other, rather, one always understands only that which one makes out of the (body) language, written or artistic information conveyed. Loosely stated: everyone always understands themselves and nobody can judge what others understand from the conveyed message. How could one? One can, after all, not very well think in the head of another or look in to check the correctness of their thoughts.
A particular ability of understanding consists of selecting what to engage with, regarding the conveyed information, for example “I think you are wrong there!”. One can firstly understand it as information (“Somebody is pointing out a wrong conclusion to me!”) or secondly as a message (“Somebody wishes to start a conversation with me!”). In the first case, one then has the possibility to think about whether one wants to engage with the possible error or whether one wishes to feel criticised. In the second case, because of the friendly tone of the message, one can decide to take seriously the error message and ask the other party for more exact details. Therefore, the choice always remains about how the person, who is understanding, picks up the motives and the way the information is presented and thus assesses its quality or checks out the information of coupled messages in order to understand something about the person who is the speaker.