from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The essence of a particular thing; those qualities that define it and make it unique.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the essence that makes something the kind of thing it is and makes it different from any other


from Wiktionary, Creative Commons Attribution/Share-Alike License

From Medieval Latin haecceitas, thisness, coined by Duns Scotus.


  • Closely related to these theories is one kind of haecceity theory, according to which individuals would be constructs of universal properties with the very important addition of one singular property (an haecceity).


  • His emphasis upon Lolita’s thisness, what Joyce called haecceity, is the unshakable foundation of his effort to restore her individuality, to break the spell of her “nymphage,” to see her as the unique woman he has uniquely damaged.

    The enactment of moral experience

  • God: concepts of | haecceity: medieval theories of |


  • This leads to a dilemma that was articulated by Steven French and Michael Redhead (1988); either quantum particles are not individuals, or they are individuals but the principle of individuation that applies to them must make reference to some kind of empirically transcendent haecceity, bare particularity or the like.

    Structural Realism

  • They are not individuated by an haecceity or primitive thisness.

    Structural Realism

  • The haecceity or thisness of an object, the property of being (identical to) that very object, provides a trivial example of an individual essence for each object.

    Essential vs. Accidental Properties

  • The haecceity of a thing is what makes this particular thing what it is in particular.

    You heard it here first ...

  • Now, “God, seeing Alexander's individual notion or haecceity, sees in it at the same time the basis and reason for all the predicates which can be said truly of him.”

    Gottfried Wilhelm Leibniz

  • Some would defend the Principle even in this case by claiming that there are properties such as being that very object A. Call such a property a thisness or haecceity.

    The Identity of Indiscernibles

  • Alternatively, the individuality of an object has been expressed in terms of its ˜haecceity™ or ˜primitive thisness™ (Adams 1979).

    Identity and Individuality in Quantum Theory


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  • Wikipedia tells us that haecceity "denotes the discrete qualities, properties or characteristics of a thing which make it a particular thing. Haecceity is a person or object's "thisness"." Then it tells us that "Charles Sanders Peirce later used the term as a non-descriptive reference to an individual." (

    February 15, 2012

  • Thus, haecceity IS that certain je ne sais quoi that people are always going on about.

    October 11, 2011

  • An abuse of Latin? It comes from Duns Scotus.

    July 16, 2010

  • I'd say it's a definitive uniqueness. as compared to quiddity, a definitive likeness.

    December 11, 2008

  • This is quite a useful word, IMO, but the definition above is vague. As far as I can tell, haecceity is the variable of thisness, the value of which, figuratively speaking of course, is a thing's ergon.

    July 11, 2008

  • Ugly. Wugly, even.

    May 8, 2008

  • 'haec' is a latin word for 'this' (declined from 'hic').

    Definitely (still) an abuse of Latin.

    December 29, 2006