 Closely related with this conflation of intensions and extensions is the fact that we mistakenly act as if the word ‘infinite’ is a “number word”, because in ordinary discourse we answer the question “how many?” with both (PG 463; cf. PR §142). But “‘[i]nfinite’ is not a quantity”, Wittgenstein insists (WVC 228); the word ‘infinite’ and a number word like ‘five’ do not have the same syntax. The words ‘finite’ and ‘infinite’ do not function as adjectives on the words ‘class’ or ‘set’, (WVC 102), for the terms “finite class” and “infinite class” use ‘class’ in completely different ways (WVC 228). An infinite class is a recursive rule or “an induction”, whereas the symbol for a finite class is a list or extension (PG 461). It is because an induction has much in common with the multiplicity of a finite class that we erroneously call it an infinite class (PR §158).