As I was reading Chisolm's "The Myth of the Given" today, I stumbled upon another reason for thinking that properties are relations. Part of Chisolm's argument validating self-justified beliefs actually included an attempt to rule out the necessity of relating things to other things outside themselves. He says:
"Common to both 'pragmatism' and 'idealism' ... is the view that to think about a thing, or to interpret or conceptualize it, and hence to have a belief about it, is essentially to relate the thing to other things, actual or possible, and therefore to 'refer beyond it.' It is this view which we must oppose..." (Chisolm in Sosa's Epistemology Anthology, 89)
Chisolm tries to establish that these relations only come up when we state the belief aloud; for instance, once I say "this appears white," then I am implying references to things like other people using the word "white" for the same experience, other events which cause statements about "white," etc. So, he says, the relations expressed in justification do not really matter for a person's belief about the experience of being appeared to whitely.
This seems intuitively refutable, because I learn to define by distinguishing. I learn what white is by distinguishing it from other colors. The content of my beliefs and knowledge (I actually don't think I have any of the real stuff at this point), entail these relations. My feeling a smooth surface necessarily involves my body and the surface, if I hear birds outside the window there must be both birds and air in which the sound can travel and ears or some sort of mechanism for the hearer. When I see green, there is not only my perception of green- there is me, the light, and the surface instantiating the green. Nothing comes in isolation. At least I think not... but then we must posit God as at least two persons.