To be worth its salt, a physical theory must meet the metaphysical constraint provided by the real-nominal essence distinction.
According to another interpretation, the real-nominal essence distinction is metaphysical, and thus more fundamental than the primary-secondary quality distinction, which is a physical distinction, belonging as it does to a particular physical theory, the corpuscular hypothesis.
The essence-existence distinction was used by Avicenna in several metaphysical contexts, i.e., in the discussion of primary concepts, of universals and of the first cause.
For objections to subjectivism, see for example, Martial Gueroult, Spinoza I – Dieu (Ethique, I) (Hildesheim: G. Olms, 1968) 50 and Appendix 3; Alan Donagan, Spinoza (Chicago: University of Chicago Press, 1989) 70; Alan Donagan, "Essence and the Distinction of Attributes in Spinoza's Metaphysics," in Spinoza, a Collection of Critical Essays, ed.
From the psychological perspective, the essence of this distinction is related to the bases of automatic appraisals (connected to System 1: Kahneman, 2011) versus reflective, deliberative appraisals (connected to System 2).
But, as Descartes recognized, the distinction between essence and existence is a distinction of reason; essence is the nature of a thing as it is contained in its definition, and existence is the perfection by which this essence actually exists which is possessed by the action of the Creator.
He rejected Avicenna's distinction between essence and existence and Aristotle's distinction between substance and accidents, possibility and actuality, and matter and form on the ground that they are mere distinctions of reason.
He denied a real distinction between essence and existence and between the soul and its faculties.
Aristotle became, in Avicenna's hands, a much more systematic and coherent thinker than he really had intended to be; problems and solutions that were, at best, hinted at by Aristotle (e.g., the distinction between essence and existence or the relation between possible and necessary existence) were among the distinctive marks of Avicenna's own work.
The Thomistic distinction of essence and existence will not be permitted.
In short, in angels too there is a distinction of essence and existence.
