bmks270 said:
That's philosophy, not math.
No, it's not. When you deal with mathematical application, these are the kinds of questions you have to answer.
The idea of measuring and modeling IQ or intelligence is another great example from Carr. You can get a score of 110, but what that represents is nothing more than a subjective abstraction of how intelligent someone is. Yes, there is a standardized way to arrive at that, but that process is still subjective. Just because you arrived at the IQ score with objective math doesn't make it an objective measurement. In the same way that adding non-random numbers to a list of random numbers still produces random numbers (depending on the magnitude of the difference), using objective math in a subjective process still produces a subjective result. In linguistic terms, just because you used objectively correct grammar doesn't mean you accurately described reality.
ETA
And back to the apple example...
How you measure apples can be highly dependent on the math you use. Are you measuring apples as discreet units and using discreet math? In that case, 1 whole apple is equal to a half eaten apple is equal to 1 rotten apple and you have 3 apples, even though that is not reflective of reality. If you're using continuous mathematics and real numbers, you might say you have 1.5 apples. Both are objectively correct and legitimate, objective math, but they yield different results because you are using objective numbers subjectively to describe something.
You can say the discreet example is BS because those are different things and you have 1 of each, which is also true, but that proves the point of math being a abstraction. You have 1, but one what? The numerical definition of 1 is absolute, but the application and what or represents is not.
The best way I can think to put it is that mathematical variables are to numbers what numbers are to reality. A variable is an abstraction that represents something mathematically (number, set, line, curve, distribution, etc) in the same way that a number is an abstraction of something in reality (apple, car, boat, house, etc).