Property. This name is given in logic to a predicable, which, without being either genus, differentia,
or species, necessarily accompanies their combination, as distinguished
from accident, which does not. Aristotle requires of a property that it
be convertible with the subject, and therefore peculiar to it. Porphyry
gives four senses of property.
1st. An attribute belonging to one only species,
though not to every specimen—as medical or geometrical skill to man.
2nd. An attribute belonging to the whole species,
though not to it alone—as biped to man.
3rd. One belonging to the whole, and to it alone, but
not to be found always, as growing grey-haired to man.
4thly. One belonging to the whole species, to it alone, and
universally—as risibility to man. This last, he says, is strictly
(κυρίως) property, and to this, following Aristotle, he confines himself
in his subsequent treatment of the matter.