Property Identity

The question of how properties are individuated is extremely important. Consider the following proposals. To be in pain is to be in a certain neurological state. To be red is to appear red to normal observers in standard conditions. To be obligatory is to maximize the good. Each makes a claim of property identity. Each is a substantive metaphysical thesis of wide interest. None can be studied with due scrutiny in the absence of a general account of property identity. Here, I will survey existing accounts and suggest a new account in terms of grounding that has some advantages over the other candidates.