Full Idea
We may define a physical property as one whose value is relevant, in some circumstances, to how a physical system is likely to act.
Gist of Idea
Physical properties are those relevant to how a physical system might act
Source
Brian Ellis (The Metaphysics of Scientific Realism [2009], 2)
Book Reference
Ellis,Brian: 'The Metaphysics of Scientific Realism' [Acument 2009], p.44
A Reaction
Fair enough, but can we use the same 'word' property when we are discussing abstractions? Does 'The Enlightenment' have properties? Do very simple things have properties? Can 'red' act, if it isn't part of any physical system?