Duns Scotus, John (c.1266–1308)
Authors: Dumont Stephen D. 
Published: September 2018

Duns Scotus was one of the most important thinkers of the entire scholastic period. Of Scottish origin, he was a member of the Franciscan order and undertook theological studies first at Oxford and later at Paris. He left behind a considerable body of work, much of which unfortunately was still undergoing revision at the time of his death. Notable among his works are questions on Aristotle’s Metaphysics, at least three different commentaries on the Sentences of Peter Lombard (the required text for a degree in theology) and a lengthy set of university disputations, the quodlibetal questions. A notoriously difficult and highly original thinker, Scotus was referred to as ‘the subtle doctor’ because of his extremely nuanced and technical reasoning. On many important issues, Scotus developed his positions in critical reaction to the Parisian theologian Henry of Ghent, the most important thinker of the immediately preceding generation and a severe Augustinian critic of Aquinas.
Scotus made important and influential contributions in metaphysics, epistemology and ethics. In metaphysics, he was the first scholastic to hold that the concepts of being and the other transcendentals were univocal, not only in application to substance and accidents but even to God and creatures. In this, Scotus broke with the unanimous view based on Aristotle that being could not be predicated of both substance and accident, much less of, except by analogy, God and creature. Scotus argued in general that univocity was required to underwrite any natural knowledge of God from creatures or of substance from accidents. Given univocity, he concluded that the primary object of the created intellect was being, rejecting Aquinas’ Aristotelian view that it was limited to the quiddity of the sense particular and Henry of Ghent’s Augustinian view that it was God. That is, Scotus argues that even the finite intellect of the creature is by its very nature open to knowing all being.
Scotus’ proof of the existence of God is the most ambitious of the entire scholastic period. Prior efforts at demonstrating the existence of God showed little concern with connecting the eclectic body of inherited arguments. Scotus’ proof stands apart as an attempt to integrate logically into a single demonstration the various lines of traditional argument, culminating in the existence of God as an actually infinite being. As a result, his demonstration is exceedingly complex, establishing within a sustained and protracted argument God as first efficient cause, as ultimate final cause and as most eminent being – the so-called triple primacy – the identity within a unique nature of these primacies, and finally the actual infinity of this primary nature. Only with this final result of infinity is Scotus prepared to claim he has fully demonstrated the existence of God. Notable features of the proof include Scotus’ rejection of Aristotle’s argument from Physics VIII (the favoured demonstration of Aquinas), the reduction of exemplar cause to a species of efficient cause, important clarifications about the causal relations at issue in arguments against infinite regress, an a priori proof constructed from the possibility of God similar to that proposed by Leibniz, and the rejection of the traditional argument that the infinity of God can be inferred from creation ex nihilo.
Scotus is a realist on the issue of universals and one of the main adversaries of Ockham’s programme of nominalism. He endorsed Avicenna’s theory of the common nature, according to which essences have an independence and priority to their existence as either universal in the mind or singular outside it. Intepreting Avicenna, Scotus argued that natures as common must have their own proper unity which is both real and less than the numerical unity of a singular; that is, natures are common prior to any act of the intellect and possess their own real, lesser unity. They are accordingly not of themselves singular, but require a principle of individuation. Rejecting the standard views that essences are individuated by either actual existence, quantity or matter, Scotus maintained that the principle of individuation is a further substantial difference added to the species. This ‘individual difference’ is the so-called haecceitas or ‘thisness’, a term used seldom by Scotus himself. The common nature and individual difference were said by Scotus to be really identical in the individual, but ‘formally distinct’. The ‘formal distinction,’ developed by Scotus chiefly in connection with the Trinity and the divine attributes, is an integral part of his realism and was as such attacked by Ockham. It admits within one and the same thing a distinction between realities, formalities or entities antecedent to any act of the intellect to provide an objective foundation for our concepts. These formalities are nonetheless really identical and inseparably united within the individual.
In epistemology, Scotus is important for his demolition of Augustinian illumination, at least in the elaborate defence of it given by Henry of Ghent, and the distinction between intuitive and abstractive cognition. Scotus rejected Henry’s defence as leading to nothing but scepticism, and set about giving a complete account of certitude apart from illumination. He grounded certitude in the knowledge of self-evident propositions, induction and awareness of our own states. After Scotus, illumination never made a serious recovery. Scotus’ other epistemological contribution was the allocation to the intellect of a direct, existential awareness of the intelligible object. This was called intuitive cognition, in contrast to abstractive knowledge, which seized the object independently of whether it was present to the intellect in actual existence or not. This distinction, credited to Scotus by his contemporaries, was invoked in nearly every subsequent scholastic discussion of certitude.
While known primarily for his metaphysics, the importance and originality of Scotus’ ethical theory has been increasingly appreciated. Scotus is a voluntarist, holding for example that not all of the natural law (the decalogue) is absolutely binding, that prudence and the moral virtues are not necessarily connected and that the will can act against a completely correct judgment of the intellect. It is Scotus’ theory of will itself, however, that has attracted the most attention. He argues that the will is a power for opposites, not just in the sense that it can have opposite acts over time but in the deeper sense that, even when actually willing one thing, it retains a real, active power to will the opposite. In other words, he detaches the notion of freedom from those of time and variability, arguing that if a created will existed only for an instant its choice would still be free. In this, he has been heralded as breaking with ancient notions of modality that treated contingency principally in terms of change over time. Scotus argued that the will, as a capacity for opposites, was the only truly rational power, where the rational was opposed to purely natural agents whose action was determined. In this sense, the intellect, as a purely natural agent, was not a rational power. Finally, Scotus endowed the will with an innate inclination to the good in itself apart from any advantage it might bring to the agent. This inclination or affection for the just (affectio iustitiae, as it was termed by Anselm), enabled the will to escape the deterministic inclination of natures toward their own perfection and fulfilment.