Haecceity may be defined in some dictionaries as simply the "essence" of a thing, or as a simple synonym for quiddity or hypokeimenon.
Harold Garfinkel, the founder of ethnomethodology, used the term "haecceity", to emphasize the unavoidable and irremediable indexical character of any expression, behavior, or situation.
In contrast to theoretical generalizations, Garfinkel introduced "haecceities" in "Parson's Plenum" (1988) to indicate the importance of the infinite contingencies in both situations and practices for the local accomplishment of social order.
[9] Gerard Manley Hopkins drew on Scotus, whom he called "of reality the rarest-veined unraveller",[10] to construct his poetic theory of inscape.
James Joyce made similar use of the concept of haecceitas to develop his idea of the secular epiphany.
[11] James Wood refers extensively to haecceitas (as "thisness") in developing an argument about conspicuous detail in aesthetic literary criticism.