Realism, nonstandard set theory, and large cardinals Original Research Article

Mathematicians justify axioms of set theory “intrinsically”, by reference to the universe of sets of their intuition, and “extrinsically”, for example, by considerations of simplicity or usefullness for mathematical practice. Here we apply the same kind of justifications to Nonstandard Analysis and argue for acceptance of View the MathML source (Basic Nonstandard Set Theory plus additional Idealization axioms). View the MathML source has nontrivial consequences for standard set theory; for example, it implies existence of inner models with measurable cardinals. We also consider how to practice Nonstandard Analysis in View the MathML source and compare it with other existing nonstandard set theories.