at the level we are discussing, i.e. restaurant bills and similar situations, math is just arithmetic. It's trivial. The capital of Israel is complicated in the same way that me paying for your lobster when all I had was a hamburger is complicated. When human judgment gets involved, nothing is easy. This web site provides dozens, hundreds, of examples of that. We'll argue about anything. — T Clark
I'm going to keep saying, "except math."
@Terrapin Station might assert that truth is whatever he says it is, in both the general and specific senses, but even Terrapin is not going to assert that 2 + 2 = 5, or, more importantly, something like "
To me, 2 + 2 = 5, even if
for you 2 + 2 = 4." Nobody ever says anything like that. Math is out of reach of all sorts of controversy, both in fact and in principle.
Let's consider the trivial notion that 1+1=2. It is five symbols strung together that is inherently meaningless. It has as much truth as covfefee. It is when one attempts to ascribes meaning to it that relativism floods in. — Rich
Do you have an example in mind of an alternative interpretation of "1 + 1 = 2"? Have you had experience with someone claiming "1 + 1 = 2" means something different from what you think it means? Relativism floods in a whole lot of places, but I really don't see it flooding in here. What does this math relativism you speak of look like?
It is true, though, that I'm rapidly running out of room here as I back into this corner. There are controversies that relate to the "higher mathematics" that Terrapin has doubts about, and there are controversies about the foundations of mathematics. There are philosophical differences about what I guess we'll have to call the "interpretation of mathematical symbolism." But these are really quite different from issues like what the capital of Israel is, whether I said I'd arrive at 7 or 8, whether Oswald acted alone, etc. And the goal is almost never some sort of relativism--it's usually still the nature of the one mathematics that's at stake. (We're getting farther afield here, which I suppose is my fault, but not to worry, because we're nearing the edge of my "expertise" too.)
It is also true that I cheated a little in my last post. The evidence most people actually rely on for the basic facts of arithmetic is either "That's what I learned in school," or "That's what the calculator/computer says." But if you consider the possibility of
debate, which is what we're interested in here, there is always an effective decision procedure to determine whether a mathematical statement is true or false. That's true for mathematics bottom to top. What counts as a proof changes as you move from bottom to top and back, but the core remains the same: an effective decision procedure. So I had this in mind as the ultimate backstop for arguments over mathematics, whether or not it's actually accessible to the people who happen to be having the argument. So there's evidence and there's evidence.
So to get back to splitting the check and such: only an effective decision procedure, even if it's just a calculation on your phone, can settle mathematical arguments--no effective procedure, no truth--but an effective decision procedure
is always available to settle any such dispute. (Until Fermat's Last Theorem was proven, no one knew whether it was true. Now we do.) There's no room to debate what to count as evidence, or how to interpret the evidence, and so forth. I guess people sort of know that, though maybe not explicitly, so they just don't argue about math the way they argue about other questions of fact. There's no point. There is also no room for "my math" and "your math," "math as I see it" and "math as you see it," etc.
For the purpose of this thread, it might be worthwhile to characterize other fields of argument by how they differ from mathematics.
PS: Should have said this too: Note that mathematicians have never
argued about whether Fermat's Last Theorem is true. They might argue about whether it was likely to be true, whether it was likely we would ever have a proof, what approach might work, and so on, but there was universal acceptance for the method of deciding whether it was true: show us the proof. What other field has that kind of unanimity?