<history of philosophy, ontology, metaphysics> thisness; the property that uniquely distinguishes each individual thing from others of its kind. Introduced by Duns Scotus as a name for the individuating essence of any particular, the term has been used more recently in connection with the view that rigidly designated individuals can exist in each of many possible worlds. Recommended Reading: John Duns Scotus, Philosophical Writings: A Selection (Hackett, 1987) and Gary S. Rosenkrantz, Haecceity: An Ontological Essay (Kluwer, 1993).
[A Dictionary of Philosophical Terms and Names]
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