Overheard a phone conversation between my wife (who came that close to getting her doctorate in math education--and taught calculus and algebra at the college level for 13 years) and her boss. Her boss said something to the effect that 2 + 2 always equals 4. Sheila said, "No, it doesn't!!! It depends on your presuppositions!" He said, "Oh yeah, happens like that in the abstract, but 2 + 2 always equals 4 in the real world" asserting we can we always depend on basic addition in the real world. Sheila retorts, "No, it doesn't!!! There's many ways in which this reveals itself in the real world. Go to a clock and add 3 hours to 10:00 and whhaddaya get??? It ain't 13. It's one!!!! Go to a calender and add two to 31 and see if you get 33. It depends on your presuppositions."
Hehehe. Once upon a time about 26 years ago I met this wonderful woman. I was driving taxi at the time with no college education. We were having this conversation and she was the first adult to tell me that I was an intelligent person and we were having this discussion about math. I mentioned something like 2 + 2 always equaling 4. She said back then, "No it doesn't." I knew I was getting into something way over my head at that point. hehehehe. Sure glad I did.