Is mathematics the only thing that exists?
Depends how you define mathematics.
And they have no physical reality, if that's what you meant.
Give this a check:
Interesting shit anon, thanks. Do you have any book recommendations in regards to mathematical philosophy? I've ordered principa mathematica for Christmas, but I'd like to learn more.
Here's one essay I recommend.
>This essay discusses the best current understanding of the relationship between mathematical and empirical knowledge. It focuses on two questions:
>1. Does mathematics have some sort of deep metaphysical connection with reality, and
>2. if not, why is it that mathematical abstractions seem so often to be so powerfully predictive in the real world?
No it's philosophy
You can't be certain that anything exists.
Mathematics in particular is defined by language, which in itself is undefined.
I can't vouch for it since it's still on my shelf but Wittgenstein's Philosophical Investigations is the go-to for examining the nature of language, which is essentially what questioning the objectivity of mathematics comes down to.
Worth noting here is that Wittgenstein was a prominent member of the most influential group of analytical philosophers who were attempting to ground language in formal logic, amongst other applications of mathematics to philosophy or practical uses, before he drifted into his later works (Philosophical Investigations) after realizing he had made a mistake about the fundamental nature of language.
Wittgenstein's remarks of the foundations of mathematics are interesting as well. He critiques set theory using some of his same criticisms he applies to the "reality" or potential objectivity of language