haecceity

noun

1. (countable, uncountable)The essence of a particular thing that gives it its unique particularity; those qualities that make an individual this specific individual and not some other.

   “He [Ignatius of Loyola] ſaith not this of ſome one Church, but of all; nor yet as of an accident proper to thoſe times of the Churches minority; but as of the Notes of every Churches Individuation or Hæcceity as they ſpeak. The Unity of the Church is characteriſed by One Altar, and One Biſhop with the Presbytery and Deacons.”

   “HÆCCEITY [with Chymiſis] the ſame ſpecifick Eſſence or active Principle, by which a Medicine operates.”

   “But then, precisely the same distinction is applicable to the Hæcceity itself. For it, too, has its notes of similarity with other Hæcceities, as well as its distinctive notes which add something conceptually distinct from the common Hæcceity.”

   “The haecceitist's claim that there exist unexemplified haecceities of disjoint objects is an extremely controversial one. Indeed, many of those who accept an ontology which includes properties vehemently deny the existence of even exemplified haecceities.”

   “What is there in the nature of individual substance which accounts for its unity and activity? As has been argued, [Gottfried Wilhelm] Leibniz did not regard haecceity as able to play this role, but frequently mentioned substantial form as a principle both of unity and activity. This makes it impossible to identify substantial form with haecceity. The strongest remaining possibility seems to be a composition of substantial form and haecceity within the nature of substance.”