You want philosophy? I got philosophy.

Reading, ahem, some metaphysics recently, my eye was stopped dead in its tracks by the word “haecceity.” It shows up in Leibniz’s Discourse on Metaphysics:

Thus the quality of king, which belonged to Alexander the Great, an abstraction from the subject, is not sufficiently determined to constitute an individual, and does not contain the other qualities of the same subject, nor everything which the idea of this prince includes. God, however, seeing the individual concept, or haecceity, of Alexander, sees there at the same time the basis and the reason of all the predicates which can be truly uttered regarding him; for instance that he will conquer Darius and Porus, even to the point of knowing a priori (and not by experience) whether he died a natural death or by poison,–facts which we can learn only through history.

The OED attributes the word to Duns Scotus (Wikipedia follows this attribution), and offers as a definition: “The quality implied in the use of this, as this man; ‘thisness’; ‘hereness and nowness’; that quality or mode of being in virtue of which a thing is or becomes a definite individual; individuality.”

Time for that third cup of coffee.