Descartes uses the term in his third meditation (Med. III) to demonstrate the existence of God, see a previous question.

The term “realitas objectiva” is a technical term from scholastic ontology.

  • How is the term defined, how does it apply, which explanatory power does the concept have?

  • Can you give a reference?

  • Why God is considered the “ens realissimum”?

I would appreciate any help from experts in scholastic theology.

  • 1
    Descartes appropriated the concept of objective reality specifically from scholastic realism of Duns Scotus. Philosophy Major gives a detailed comparison of what it meant to the two of them.
    – Conifold
    Commented Nov 30, 2023 at 7:06
  • 1
    "scholastic" is not an easy topic... In a nutshell, an "idea" (concept) has "formal reality" when it is considered as a product of the mind (a "mental object") and has "objective reality" when it is considered wrt the object it represents. See Formal versus Objective Reality in Descartes. Commented Nov 30, 2023 at 8:51
  • 1
    See also Descartes: Ideas and The Formal-Objective Reality Distinction: "When speaking of ideas as representing things to the mind, Descartes will refer to an idea’s objective reality. The objective reality of a thing is the kind of reality a thing possesses in virtue of its being a representation of something." Commented Nov 30, 2023 at 9:00
  • 1
    And see Being, Formal versus Objective into The Cambridge Descartes Lexicon. Commented Nov 30, 2023 at 9:06
  • @MauroALLEGRANZA Concerning your comment in a nutshell: It seems like much ado about nothing: formal reality = the concept in the mind; objective reality = the referent of the concept in the external world. - Many thanks for your support with all your references - I will look them up; at least some of them :-)
    – Jo Wehler
    Commented Nov 30, 2023 at 9:18

1 Answer 1


Heidegger describes an inversion of meaning of realitas objectiva from Descartes and Scholasticism to Kant and modernism (depending on your subscription), in The Basic Problems of Phenomenology, Chapter One Kant's Thesis: Being Is Not A Real Predicate p. 37–38.

[Kant] separates objective reality as actuality from possibility. If I devise or invent some possible thing, then in doing so I am occupied with this imagined thing's pure relationships having real content, though without thinking of the thing with these relations as being actual, presently existent. In retrospect, this use of reality occurs also in Descartes. Descartes says, for instance, that error, and in general everything that has negative value, everything malum, non esse quid reale, is nothing.11 This does not mean that error does not actually exist; instead, error is surely actual, but it and everything evil and bad is not a res in the sense that it would be an independent real content for itself. It is always only advenient and it is only by means of the negation of an independent real content, by the negation of the good. Similarly in the proof for God's existence in the third meditation, when he is speaking of realitas objectiva and realitas actualis, Descartes here, too, takes realitas in the sense mentioned above—the sense of realness or res-ness, German Sachheit—equivalent to the Scholastic quidditas [whatness, somethingness]. Realitas objectiva is not identical with the Kantian objective reality but just the opposite. In Descartes realitas objectiva means, following Scholasticism, the objectified what, which is held over against me only in pure representation, the essence of a thing. Realitas objectiva equals possibility, possibilitas. In contrast, what corresponds to the Kantian concept of objective reality, or actuality, is the Cartesian and Scholastic concept of realitas actualis—the what which is actualized (actu). This noteworthy distinction between the Cartesian concept of realitas objectiva as tantamount to subjectively represented possibility and the Kantian concept of objective reality, or that which is in itself, is connected with the fact that the concept of the objective [Objektive] was turned into its exact opposite during this period. The objective, namely, that which is merely held over against me, is in Kantian and modern language the subjective. What Kant calls the subjective is for the Scholastics that which lies at the basis, hupokeimenon, the objective, thus corresponding to the literal sense of the expression "subject."

  1. Descartes, Meditationes de prima philosophia, Latin-German edition (Felix Meiner, 1959). Meditation 4, p. 100.

Ens realissimum is mentioned earlier on page 37 and on page 148.

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