I'm equally at a loss as to why you think I believe it isn't. I know it's circular. well OK, but you didn't say that until just now in response to me and simont saying it's circular reasoning, so you can see how I got there!

I don't base my use of it on anything, I just use it, which is why I call it an axiom, and that was the sense of "axiomatic" that I thought you and lizw meant all along. It now seems that isn't what you meant, so I'm hoping to find out what sense you do mean.