Full Idea
To say there are properties is to say there are natural classes, classes introduction to some of whose members enables people to pick out others without hesitation and in agreement.
Gist of Idea
Properties imply natural classes which can be picked out by everybody
Source
Anthony Quinton (The Nature of Things [1973], 9 'Nat')
Book Reference
Quinton,Anthony: 'The Nature of Things' [RKP 1973], p.263
A Reaction
Aristotle would like this approach, but it doesn't find many friends among modern logician/philosophers. We should go on to ask why people agree on these things. Causal powers will then come into it.