He argues that this concedes the need to explain non-identity, in which case the Principle itself is required in the case of simple things. Against Della Rocca, it may then be argued that for simples (things without parts) non-identity is a brute fact.  This is in accord with the plausible weakening of the Principle of Sufficient Reason that restricts brute facts, even necessary ones, to the basic things that depend on nothing further. 