For its countenancing an everlasting domain of abstract objects which mathematics is supposed to describe, platonism has often been charged with generating two undesirable gaps. The first gap separates both the activity of mathematicians — their elaborating theories and conducting proofs — and the result of their activity — the system of those theories, namely mathematics as a discipline which evolves in human history thanks to human beings — from mathematics' subject matter — what it is about and what it describes. This is the gap signalled by Benacerraf's dilemma and, more generally, by the problem of access, which the dilemma raises in all its meaningfulness. The responses discussed in Chapter 5 try to fill this gap in various ways, while those discussed in Chapter 4 deny it, either by rejecting its very premise — platonism — or by giving a more palatable reading of it. The second gap separates mathematics itself — which, despite its being the outcome of a human activity, is often described by the platonist as embodying the sort of necessity stemming from the independence of the objects this activity describes — from the roundabout, contingent and always perfectible attempts science makes in order to account for the material and corruptible world which surrounds us and to which we belong. This is the gap IA intends to fill by appeal to the notion of indispensability.