 Like the definition of intrinsicness in terms of duplication, the definition of qualitativeness in terms of qualitative indiscernibility fits most naturally with a view where necessarily equivalent properties are always identical, since it will not allow us to say, e.g., that being red is qualitative but being red and either admiring or not admiring Lewis is non-qualitative. For proponents of finer-grained theories of properties who want to make such distinctions, the strategy of analysing qualitativeness in terms of qualitative indiscernibility seems unpromising. But the project of analysing qualitativeness in terms of perfect naturalness remains on the table. For example, invoking the notion of “full definability” discussed in  §4.10  below, one might define a qualitative property as one fully definable from perfectly natural  properties.[27] 