Set theory and logic are too interdependent to venture far in one whilst steering clear of the other. For instance, you'll only really skim the surface of model theory without a basic understanding of infinite cardinals.
They can indeed be used together and are interdépendant in practice at "high level mathematics"
But set theory is made of a lower level primitive (first order logic) itself being an extension of zeroth order logic.
I was saying that in the context of learning the foundation of mathematics where set theory is not the first place to begin.
I'd say most intuition matches the reals, even if people's explanation of it would not match the definition.
You just need to walk someone through 'sqrt(2) is irrational ' and 'pi is transcendental' and you essentially end up with 'I want all converging sequences in Q to have a limit'. Which gives you the reals.
In some sense, the reals are the most naive number system. Just start with the natural numbers, and allow every sensible opperation.
> In some sense, the reals are the most naive number system. Just start with the natural numbers, and allow every sensible opperation.
It is simple only in retrospect. It took a few millennia for mankind to reach the definition of the reals. Meanwhile, Archimedes, Euclid, Pythagoras, al-Kwarizmi, Newton, Fermat, Gauss, Euler, Jacobi, Newton, Galois, Bernoulli, Laplace, Lagrange, Fourier did quite a lot of things (which are very relevant for all fields of math today) without even knowing the definition of limit!
It's a stretch to say that people after Newton did not know what a limit was. It's just that they did not have the formal definition of one.
Newton invented limits. Only he did not have a fundamental basis for it. Hence, he saw it is a dirty trick that happened to yield correct and useful results.
The formalization of limits came later when the intuitive use of a limit started failing. If I recall, this was with the Weierstrass function.
I think we agree though. You can do most maths just by assuming you can do things with the rational numbers. It takes some really weird stuff before you need to properly define the 'real-numbers'.
Yes indeed, one does not need to first learn zeroth order logic for doing maths.
I was talking for one that want to learn from the root of mathematics, some people believe that set theory is the foundation while it is a composition of lower level primitives
