Full Idea
Regularity theories of laws face the grue problem. That, I think, can only be got over by introducing properties, sparse properties, into one's ontology.
Clarification
See Idea 4783 for the problem of 'grue'
Gist of Idea
The introduction of sparse properties avoids the regularity theory's problem with 'grue'
Source
David M. Armstrong (Properties [1992], §2)
Book Reference
'Properties', ed/tr. Mellor,D.H. /Oliver,A [OUP 1997], p.171
A Reaction
The problem is, roughly, that regularities have to be described in language, which is too arbitrary in character. Armstrong rightly tries to break the rigid link to language. See his Idea 8536, which puts reality before language.
Related Ideas
Idea 8536 We want to know what constituents of objects are grounds for the application of predicates [Armstrong]
Idea 4783 Observing lots of green x can confirm 'all x are green' or 'all x are grue', where 'grue' is arbitrary [Mautner, by PG]