  Alternatively, the individuality of an object has been expressed in terms of its ‘haecceity’ or ‘primitive thisness’ (Adams 1979). As the name suggests, this is taken to be the primitive basis of individuality, which cannot be analysed further.  However, it has also been identified with the notion of self-identity, understood as a relational property (Adams ibid.) and expressed more formally as ‘a=a’. Each individual is understood to be identical to itself. This may seem like a form of the property-based approach we started with, but self-identity is a rather peculiar kind of property. As we’ll see, denying that quantum objects are self-identical may be one way of capturing the idea that they are non-individuals. 