Scotus was probably born in Scotland around 1265. He was ordained as a priest in Northampton (England) and became one of the most important theologians of the late Middle Ages. He lectured on Peter Lombard's Sentences twice in Paris (1302 and 1304) and in Oxford and was named Doctor Subtilis (the Subtle Doctor) for his penetrating manner of thought. He was dispatched, likely in October 1307, to the Franciscan studium at Cologne, where he died.

Although Duns Scotus's texts became accessible after 1639, it is unlikely that Descartes was acquainted with them. Indeed, Descartes had studied at the Jesuit Collège de La Flèche, where Thomas Aquinas was the acknowledged authority. However, Descartes indirectly knew Scotus, because he studied the texts of Francisco Suárez, who often cited Scotus's views, and especially because Suárez himself had been deeply influenced by Scotus's philosophy, as had been Eustachius a Sancto Paulo, with whose Summa philosophica Descartes was acquainted.

Descartes cites Scotus only once, in replying to Caterus. There, he refuses to accept a “formal” distinction, as Scotus suggested, not reducible to a “modal” one (AT VII 120, CSM II 85–86) (see distinction [real, modal, and rational]). Notwithstanding the absence of direct references, Scotus's influence on Descartes’ philosophy surfaces even in the terms used in the latter. Attributing clarity and distinctness to the mind's cognitions has its ancestry in Scotus (and even earlier in the Stoics). According to Scotus, clear knowledge requires that the object be present to the mind, and distinct knowledge of a thing is knowledge of its essence(Ordinatio I, d.3, p.1, q. 1–2;1950, 3:50).

The following Scotistic doctrines play a key role in Descartes’ philosophy.

1.The Doctrine of Objective Being (esse obiectivum)

Scotus deeply modified Aquinas's views concerning the knowledge that God has of what can be created. According to Aquinas, the essences of finite things are the relations between what can be created and the infinite divine essence, and God knows them by knowing his essence. According to Scotus, by contrast, God knows the relation between a thing's essence and his divine essence only after having endowed the thing's essence with an esse intelligibile (intelligible being). The thing's esse intelligibile is the object of divine knowing (its esse obiectivum), which Duns Scotus distinguishes from the formal side of divine thought – the act of thinking (see being, formal versus objective).