"Well, we won't quarrel about a word," said the other, pleasantly. "Why on earth not?" said MacIan, with a sudden asperity. "Why shouldn't we quarrel about a word? What is the good of words if they aren't important enough to quarrel over? Why do we choose one word more than another if there isn't any difference between them?
From The Ball and the Cross, by G.K. Chesterton
This quote reminds me of an online conversation that was a watershed moment for me in my understanding of language and truth. A number of years ago, I watched an email exchange take place on a parenting email list where one person insisted she was a vegetarian even though she ate various meats not infrequently. They went back and forth several times, until the so-called vegetarian stated that she was the one using the word, she could define it however she wanted to define it. All of a sudden the absurdity and the absolute chaos implied by her statement hit me, and I found myself entertaining the previously ridiculous idea that there could be absolute knowledge in something that wasn't physically measurable.