The general subject of relevance is interesting. In court, the judge may say, "Relevance, Mr. Smith?" or "What is the relevance of this line of discussion?" At least, they do in court movies I have seen. Notice that both remarks are questions. When the judge or president says "You are out of order" or "I don't recognize you", the utterance is not a question. But the matter of relevance is squishier, less black and white.
One of most poignant attempts to be social I ever came across was the picture of an 11 year old somewhat autistic girl thrilled to have moved into a new neighborhood. She was said to run up to the mailman and try being social with the opening remark "6 times 7 is 42!" A savvy adult might reply in a cheerful and uplifted voice that it certainly is, isn't it? The sort of opening social remark made by the girl reminds me of a passage in Hayakawa's "Language in Thought and Action". I read the book in high school more than 50 years ago but the passage is still in my head. When changing a flat tire, the Japanese-American said, and someone passing by says "Flat tire?", don't explode in anger. Do what your mother or sister does and recognize the remark as an attempt to be social, to sympathize with your problem.
In statistics, irrelevance is called "independence". Of course, it is valuable to find that one variable is related to another, maybe even causes the other to move up or down, as more calories tend to make more body fat. But finding independence can be valuable, too. Then, one variable has no effect on the other. In actual fact, there are few things in this world that are truly unrelated to each other. One thing is usually related to another, even if the connection is weak and complex. A measure of genius or persistence is the ability to understand and explain important but not obvious connections.
Communication is tricky and can be used in many ways. A seductive voice can purr "Got a light?" and a menacing one can growl the same words with very different purposes and meanings. That a remark was made at all, or the tone and timing used, can be the real message.
