We were discussing today in the metaphysics course the very idea of thisness - of haecceitas. Given a frame of reference - it could be the keepers of proper names, a repository of labels or a finger pointing at a particular - something can be tracked independently of anything universal (like qualities or properties). I always thought that there ought to be something of this idea played whenever one is pressed with a challenge related to the identity of indiscernibles. De re tracking is the first way that comes to mind when we try to avoid taking particulars as examples. The original Duns Scotus haecceitas was applied to objects - concrete particulars. Pointing at one object and not another (maybe indiscernible from the first) makes it this object and not the other. Whenever pointing - any kind of indexicality, proper names, for example - is possible, we can deal directly with particulars. We can then take an object as whatever is pointed and not as an instance of something universal. We use indexicals to present examples - this is a chair, Socrates is a philosopher - so that we can see the universal in the particular being pointed. (It is no coincidence that Wittgenstein talks about the many possible understandings of a pointing gestures at the end of section 185 in the Investigations: it is a section about how pointing can deceive, we point at a sequence of numbers but we cannot be sure at pointing at what that sequence intends to stand for - or exemplify. Demonstrative reasoning is the crux of the matter.)
But also when we talk about tropes - abstract particulars - the best thing to do is to present them by demonstration: this red, this way of being square etc. We can also present a trope by showing other tropes similar to it. But then we are already pointing at particulars. Pointing is relating to particulars no matter whether they are abstract or concrete.
And still we can also use pointing to present something universal (the concrete, the abstract but also the universal pole of the square of these four properties thought to be so seminal). This is the case when McDowell talks about demonstrative concepts. I point at a colour and say: this colour. It is a concept I´m refering - what I take to have an universal element. But I´m presenting it by pointing. I can master the concept of that shade of blue - think of those colour books in catalogues for products - while I´m looking at it but not without the shade being pointed. I cannot grasp the concept in terms of other concepts (other universals) just like qualities are not enough to specify the object I´m pointing when there are other, indiscernible ones. Yet, the concept has universal application. And it revolves around a haecceitas.