An hour or so later L shoots me an email. Its tone is humorous. L. gives numerous examples of how this or that ideology might try to deny that 1 + 1 = 2; someone on the Stalinist left for example, might try to claim that 1 + 1 = 2 is a bourgeoise plot. I can't capture the wit here, so I won't try, except to say that it is similar to the math lessons offered by the Primate Diarist.
Of course, L. fails to give me a serious argument that 1 = 1 =2 (when the numerals are interpreted as being in base 10) is a relative truth.
With some trepidation -- because I periodically make an ass out of myself by trying to turn a witticism into a Serious Philosphical Issue, I try to get a serious argument out of L.
"I understand what Galileo means when he says that speed is relative to some frame of reference," I tell him." What Galileo says is intuitive and makes sense. It is well-defined. I am jogging at 4 miles an hour relative to the plaform underneath my feet; I am jogging at 69 miles an hour relative to the earth when it turns out that my plaform is a train moving at 65 miles an hour."
"But I don't understand what you mean when you say that truth is relative. 1 + 1 (when the numerals are interpreted as being in base 10) equals 2 relative to one reference frame but equals 3 (again, we are still talking base 10) relative to another? Please explain yourself."
"And please make the explanation as intuitive and well-defined as the Galileo's theory that speed is always relative to some frame of reference."
"Until I get this explanation, I will stay with this notion of truth: the proposition 'The cat (with NAME Princess) is on the mat (with MAT_ID 16971 encoded in the bar code) is true if and only if the cat (this particular cat) is on the mat (this particular mat). No need here to muddy the waters with some ill-defined notion about relativity."