This is taken to be a particular problem for platonism, since this view postulates the existence of mathematical objects, and one would expect such objects to play a role in the acquisition of mathematical knowledge. After all, on the platonist view, such knowledge is about the corresponding mathematical objects. However, despite various sophisticated attempts by platonists, there is still considerable controversy as to how exactly this process should be articulated. Should it be understood via mathematical intuition, by the introduction of suitable mathematical principles and definitions, or does it require some form of abstraction?