I'm on a bit of a Jewish jag at the moment, in part under the influence of my Jewish friend Peter who turned me on to Soloveitchik. But Peter should labor under no false expectation that he will convert me to any version of Judaism; it is more likely that I shall get him out on the Rio Salado on a truck tire inner tube whereupon I shall baptize him in nomine Patris et Fillii, et Spiritus Sancti, and indeed by full immersion, not by the 'watered down' Roman rite.
Joking aside, here is an interesting passage from Moses Maimonides (The Guide to the Perplexed, Dover, p. 80) which is related to my ongoing conversation with Dale Tuggy, the Protestant theistic personalist:
It is known that existence is an accident appertaining to all things, and therefore an element superadded to their essence. This must evidently be the case as regards everything the existence of which is due to some cause: its existence is an element superadded to its essence. But as regards a being whose existence is not due to any cause -- God alone is that being, for His existence, as we have said, is absolute -- existence and essence are perfectly identical; He is not a substance to which existence is joined as an accident, as an additional element. His existence is always absolute, and has never been a new element or an accident in Him. Consequently God exists without possessing the attribute of existence. Similarly He lives, without possessing the attribute of life; knows, without possessing the attribute of knowledge; is omnipotent without possessing the attribute of omnipotence; is wise, without possessing the attribute of wisdom: all this reduces itself to one and the same entity; there is no plurality in Him, as will be shown.
Question: Could existence be an accident of all things that are due to some cause? And if it is not an accident, is it essential to them?
Max, a cat of my acquaintance, exists and exists contingently: there is no broadly logical necessity that he exist. His nonexistence is broadly logically possible. So one may be tempted to say that existence is to Max as accident to substance. One may be tempted to say that existence is accidental to Max. In general, the temptation is to say that existence is an accidental property of contingent beings, and that this accidentality is what makes them contingent.
But this can't be right. On a standard definition, if P is an accidental property of x, then x can exist without P. So if existence were an accidental property of Max, then, Max could exist without existing. Contradiction.
Ought we conclude that existence is an essential property of Max? If P is an essential property of x, then x cannot exist without P. So if existence were an essential property of Max, then Max cannot exist without existing. The consequent of the conditional is true, but tautologically so.
From this one can infer either that (i) Max is a necessary being (because he has existence essentially) or that (ii) existence construed as an essential property is not the genuine article. Now Max is surely not a necessary being. It is true that if he exists, then he exists, but from this one cannot validly infer that he exists. Suppose existence is a first-level property. Then it would makes sense to say that existence is an essential property of everything. (Plantinga says this.) After all, in every possible world in which Max exists, he exists! But all this shows is that existence construed as an essential property is not gen-u-ine, pound-the-table existence. Gen-u-ine existence, the only kind I care to have truck with, is existence that makes a thing be or exist, and, to be sure: outside the mind, outside language and its logic, outside its causes, outside of nothing. With a quasi-poetic, Heideggerian flourish: existence is that which establishes a thing in its Aufstand gegen das Nichts, its insurrection against Nothingness.
We ought to conclude that existence is neither accidental to a contingent thing, nor essential to it. No contingent thing is such that existence follows from its essence. And no contingent thing is such that its contingency can be understood by thinking of its existence as an accidental property of it. The contingency of Max's being sleepy can be understood in terms of his instantiation of an accidental property; but the contingency of his very existence cannot be so understood.
If every first-level property is either accidental or essential, then existence is not a first-level-property. But, as I have argued many times, it does not follow that existence is a second-level property. The Fregean tradition went off the rails: existence cannot be a second-level property. Instantiation is a second-level property, but not existence. And of course it cannot be a second-level property if one takes the real distinction seriously, this being a distinction between essence and existence 'in' the thing or 'at' the thing.
Where does this leave us? Max exists. Pace Russell, saying that Max exists is NOT like saying that Max is numerous. 'Exists,' unlike 'numerous,' has a legitimate first-level use. So existence belongs to Max. It belongs to him without being a property of him. One argument has already been sketched. To put it explicitly: Every first-level property is either essential or accidental; Existence is neither an essential nor an accidental first-level property; ergo, Existence is not a first-level property.
Existence belongs to Max without being a property of him. How is existence 'related' to Max if it is not a property of him?
My existence book essays an answer, but it too has its difficulties.
Existence is one hard nut to crack.