Quiddity and haecceity

Quiddity is the property a thing has of being the kind of thing that it is, whereas haecceity is the property of being the very thing that it is and no other. Both of them are essences, but quiddity is the essence of universals, whereas haecceity is the essence of particulars.

1 comment:

Uche Ogbuji said...

Hmm. I thought the main difference was that "quiddity" could be the essence of a person or a thing, and that haecceity only applied to things. I think there is precedent for "quiddity" to cover phenotype as well as genotype, although since I have no full OED it may be a while before I find one (the well-known usage in "Hudibras" is indeterminate, I think). Of course, it's also worth noting the second meaning of "quiddity" as approximately "hair-splitting". And a final aside: another delightful import of Latin "quid" is in the phrase "tertium quid".