 It should be noted that it is possible to do a significant amount of mathematics while obeying predicativist scruples. The set of natural numbers cannot be defined in the predicative version of TST, but the set of singletons of natural numbers can be defined and can be used to prove some instances of induction (enough to do quite a bit of elementary mathematics). Similarly, a version of the Dedekind construction of the real numbers can be carried out, in which many important instances of the least upper bound axiom will be provable.