And when Joe started doing something new, you'd just extend your formal system to include all of Joe's new behaviors. Given enough symbolic content, no matter what Joe comes up with, you can model it.
Just like we extended our formal number system into negatives, imaginaries, quaternions, etc.
Math is a terrifically abstract, self-consistent model of reality. But that's all it is: a model. Sometimes the model tells us things we didn't know before, and sometimes we have to change the model to make it work with what we're observing.