Right. Now on to Platonism.
Carnap tried to push the line further back. He said this talk of a system misses the point. Math is just a game we play, and we can play any game we want. We just happen to prefer the math game in some contexts. If you want to play another, go ahead. People do it all the time when they speak English, which is also just another game. Math is not a system, really–rather, you should think of it as a linguistic, social practice. The nice part about this Carnapian approach is that it has a very consistent answer to infinity: Infinity is just part of the math game. It’s like home-runs in baseball. Home-runs don’t exist outside of baseball–that would just be a ball flying over a fence. But because of the rules of baseball, there are home-runs in the game. The rules of the game of math simply prescribe that there is no greatest number. In counting, “1, 2, 3…” there is only the language practice of writing “…” That’s all that infinity is. Yet again, however, you can ask Carnap, “So what are these games? Are they genuine entities? Why is it that this particular game is so successful in living life and firing rockets? Do the individual games live within the greater category of games, and is this category a genuine object? What happens when we stop playing this game? Does math disappear?”
This is not what Carnap said, in fact its in direct contradiction to his formalist view of mathematics as just being a formal system. I think youre confusing him with (eg) the later Wittgenstein.
Carnap would have agreed that infinite only comes into mathematics when/if we introduce it into our symbolism, but I think he would have disagreed with most of the other claims youve attributed to him (most notably “this talk of a system misses the point”, and “Math is not a system, really–rather, you should think of it as a linguistic, social practice”).
So as the tally stands, Platonism has not been proved nor has it been disproved. All thus-far conceived contraries of Platonism have proved contradictory, but there is no evidence that this is a complete list of non-Platonist perspectives. So it should be clear that any answer to the question has to be original or Platonic. Which it is, I do not know.
What do you mean by ‘proving Platonism’? What sort of thing would count as evidence for it?
Anyway, its incorrect to say that the contraries of Platoism have proved contradictory. For instance, Formalism is perfectly consistent, its just pointless and ducks the interesting questions. Intuitionism is consistent, its just very complex and cant reconstruct all of classical mathematics. None of the more empirical positions which have become more popular recently (eg those espoused by Polya, Putnam, etc) are contradictory either (and imo they are a lot closer to the truth than any of the traditional approaches - I would recommend this as an excellent introduction to ‘quasi-empiricist’ philosophies. On a sidenote, while Objectivism doesnt have a philosophy of mathematics as such, I would tentatively suggest that this has more in common with what I see as being the ‘spirit of Objectivism’ than the traditional approaches do)
Also, 1/x wouldn’t work either if you permit x to be 0, since that would make it undefined. I’m not sure what you’re saying by, “not 0/x which would become undefined as x –> 0,” since 0/1 is defined. It’s 1/0 that is not defined, unless what you meant was that 0/x could turn out to be 0/0, which is also undefined. Perhaps you have some special use of ‘–>’, because for me it is a logical symbol meaning ‘if… then’.
-> means ‘tends to’, its used to denote the limit of a function/sequence. Its the value which the sequence is getting closer and closer to, as the variable obeys some condition. For instance, the function f(x) = 1/x tends to 0 as x tends to infinite, because as x gets bigger and bigger, f(x) gets smaller and smaller. Hence we write “f(x) -> 0 as x-> infinity”. Similarly, we would write “f(x) -> infinity as x-> 0”, since 1/x becomes larger and larger as x gets closer to 0.