• WordNet 3.6
    • n haecceity the essence that makes something the kind of thing it is and makes it different from any other
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Chambers's Twentieth Century Dictionary
    • n Haecceity hek-sē′i-ti Duns Scotus's word for that element of existence on which individuality depends, hereness-and-nowness.
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Chambers's Twentieth Century Dictionary
Lit. 'thisness,' L. hæc.


In science:

One might take the modern reemergence of the hole argument in GTR [Earman and Norton, 1987] as evidence of this realism among philosophers of science, though doubtless modern mathematicians’ fondness for active diffeomorphisms (which seem to require mathematical haecceities) has also contributed.
Empirical Equivalence, Artificial Gauge Freedom and a Generalized Kretschmann Objection
It is not difficult to formalize this argument and to prove that the existence of irre flexi ve physical relations grounds the multiplicity of objects, without recourse to haecceities.
How Classical Particles Emerge From the Quantum World
It makes little sense to wonder whether Leibniz’s Principle is satis fied by identical quantum particles, or whether t hey possess haecceities, if the existence itself of these particles has not been established.
How Classical Particles Emerge From the Quantum World
Teller, P.: Quantum Mechanics and Haecceities.
How Classical Particles Emerge From the Quantum World
Hence they do not possess the property of “being this very particle”, known to philosophers as “thisness” or “haecceity”.
Quantum Mechanics and the Cookie Cutter Paradigm