Full Idea
The realist view of resemblance nominalism is that it is resemblance that needs explaining. When there is resemblance it is natural to want to explain it, in terms of something held in common. Explanations end somewhere, but not with resemblance.
Gist of Idea
Resemblance itself needs explanation, presumably in terms of something held in common
Source
Alexander Bird (Nature's Metaphysics [2007], 2.1.2)
Book Reference
Bird,Alexander: 'Nature's Metaphysics' [OUP 2007], p.15
A Reaction
I smell a regress. If a knife and a razor resemble because they share sharpness, you have to see that the sharp phenomenon falls within the category of 'sharpness' before you can make the connection, which is spotting its similarity.