Full Idea
To explain how tropes form bundles, concurrence relations are invoked. But tropes F and G and a concurrence relation C don't ensure that F stands in C to G. So trope theory needs 'instantiation' relations (special relational tropes) after all.
Gist of Idea
If tropes are linked by the existence of concurrence, a special relation is needed to link them all
Source
Chris Daly (Tropes [1995], §7)
Book Reference
'Properties', ed/tr. Mellor,D.H. /Oliver,A [OUP 1997], p.157
A Reaction
Campbell presents relations as 'second-order' items dependent on tropes (Idea 8525), but that seems unclear. Daly's argument resembles Russell's (which he likes), that some sort of universal is inescapable. It also resembles Bradley's regress (7966).
Related Ideas
Idea 8525 Relations need terms, so they must be second-order entities based on first-order tropes [Campbell,K]
Idea 7966 Relations must be linked to their qualities, but that implies an infinite regress of relations [Bradley]