Full Idea
Abelard's problem is that it is not clear how singular forms could do the job they are supposed to do - to account for abstraction, namely - if they were purely singular aspects.
Gist of Idea
Abelard's problem is the purely singular aspects of things won't account for abstraction
Source
comment on Peter Abelard (works [1135]) by Claude Panaccio - Medieval Problem of Universals 'Peter'
Book Reference
'Routledge Companion to Metaphysics', ed/tr. Le Poidevin/Simons etc [Routledge 2012], p.52
A Reaction
A very nice question! If we say that abstracta are just acquired by ignoring all but that feature in some objects, how do we identify 'that' feature in order to select it? The instances must share something in common to be abstracted.