Abstract
Among those who posit properties, liberals (mostly nominalists) admit abundant, ontologically free properties, which particulars possess whenever they satisfy the same predicate and belong to the same class, however artificial. I call them “L-properties” (for “Liberal”). Some liberals also admit that some few L-properties are natural, while most of them are artificial (the same applies to the corresponding classes). Others (mostly but not only realists) commit to a more discriminating use of the category: properties are sparse, they make for the objective similarities among particulars, and more importantly, they allow to analyze “objective similarity” and “class naturalness” in terms of property-possessing and sharing. They give particulars their “true nature”, and I call them “A-properties” (for “Analytical”). This article provides a defense of this second type of properties, in the particular case of sortals. To that end, a new fact is put forward: that sorts are classes which are natural not as a primitive feature, but in virtue of what the particulars which belong to them are, and which makes them _naturally belong_ to them. I then argue that this fact entails the existence of the desired type of properties, “sortal A-properties”, although leaving open the question of how they should be construed.