I made a mistake in my post when I wrote 4 = cos(x) + sin(y). Regardless of what x and y are, the equation can never result in a value greater than two. I noticed the mistake before I posted, but I decided to leave it there because I believe it contains two great truths.
The first truth is that we often make mistakes even when we fully understand what we are talking about. Can you imagine how many mistakes we make when we are not entirely familiar with the subject?
The second truth is that, no matter how you look at it, truth exists. Now you, Dick, and a few others are willing to maintain that the concept of truth is not important. While I can't possibly deny your right to assert that, I reserve the right to think that, if truth is not important, then nothing you say is important.
I have a definition of truth that is completely arbitrary and I'm not capable of giving you a philosophical justification for it. At the same time I don't think I have to; it's my game and if everyone is free to lay down their own rules for communication then so am I. That is, if you want to talk to me then you have to speak my language, just as much as if I want to talk to you I must speak your language.
Now look at it closely, it's a serious problem. If we all go about inventing personal languages, then communication is impossible. Sadly, that is exactly the state we find ourselves in. There must be a way out, but each person has to find that way for themselves.
I don't have time to write more for now. You are into philosophy, so let me tell you something you might be able to relate to. I discovered that my position regarding truth, language, and logic has been put forward by a group of 19th-century philosophers known as Logical Positivists. If you want to understand were I'm coming from, let's use logical positivism as a basis. Just keep in mind I'm as fluent with philosophy as you are with math.