 The Relevant Similarity Question: Generalizing  (RR4)  above, Roca-Royes speaks of relevant similarity of an object with its counterpart. But what are the relevant respects of similarity, and how do we know that? This seems to be the most crucial question in Roca-Royes’ account. Roca-Royes addresses the issue of relevant and irrelevant similarity for the concrete cases she discusses in her 2017 work (like Messy and Twin-Messy). However, Roca-Royes concedes that the details for the generalizability of these considerations about relevant similarity are still to be worked out in full detail. (For further critical discussion of Roca-Royes’ account see Prelević 2015)