[ChrisV]

This is a semantic question about the definition of "exists". For instance, you could argue like this: the martial art of karate has no substance and therefore doesn't exist, so karate competitions are a figment of your imagination. The problem is that karate isn't a thing, it's a description of a complex set of processes. Math and logic are processes, not things. If you define "exists" as "is a thing", then you come up with the answer that math and logic don't exist.

I think it's true to say that math and logic are derived from reality rather than being fundamental, though. As with science, the reason we use them is that they model reality accurately. Sometimes different mathematics is required to model different aspects of reality - e.g. Euclidean geometry for "real world" tasks and Riemannian geometry for the curvature of space-time, although the difference there is in the axioms rather than the process. Quantum computing is an example of a field where a new type of logic is having to be invented to describe reality.