  In order to resolve this issue, Sylvan makes two moves. First of all, he introduces the distinction between characterizing and non-characterizing properties. The former are necessary in order to define the essence of an object. A characterizing property is a property (e.g., being a detective or being smart) that is necessary in order to make a specific item (e.g., Sherlock Holmes) the item that it is. Using Sylvan’s words: