Full Idea
The 'companionship difficulty' cannot arise if the members of the resemblance class are tropes rather than whole concrete particulars. The instances of having a heart, as abstract particulars, are quite different from instances of having a kidney.
Clarification
See Idea 7956 for Goodman's 'companionship difficult'
Gist of Idea
Tropes solve the Companionship Difficulty, since the resemblance is only between abstract particulars
Source
Keith Campbell (The Metaphysic of Abstract Particulars [1981], §6)
Book Reference
'Properties', ed/tr. Mellor,D.H. /Oliver,A [OUP 1997], p.134
A Reaction
The companionship difficulty seems worst if you base your account of properties just on being members of a class. Any talk of resemblance eventually has to talk about 'respects' of resemblance. Is a trope a respect? Is a mode an object?
Related Idea
Idea 7956 If all and only red things were round things, we would need to specify the 'respect' of the resemblance [Goodman, by Macdonald,C]