In order to preserve his rationale for real contingency, John Duns Scotus affirms a distinction between “nature” and “will”. Scotus does not outright reject the Aristotelian principle “that which is moved is moved by another”. Instead, he grants that this principle applies to all “natures”. The exception to the rule applies to “wills”. Scotus cleverly finds justification for this distinction by appealing to Aristotle’s discussion of chance and luck in the Metaphysics.
According to Scotus, the will is “self-moved” and able to determine itself. This is what Wolter calls the “superabundant sufficiency of the will”. Without the active power to be self-moved, a will could not truthfully be called a “will”. Scotus posits that one cannot reduce the will and the act of willing to anything more basic. A will is a rational potency and is able to will (or not will). The will is different from a nature because it possesses the potency to accomplish opposite ends. A nature can only be moved by another. Wills move contingently. Natures move necessarily.
Scotus does grant that the human will possesses an affection corresponding to a nature and an affection that assures that the will does itself possess radical contingent potency. The affectio commodi or “affection for the advantageous” is moved by another and seeks the agent’s well-being. However, the affectio justitiae or “affection for justice” is self-moved and is the source of the innate freedom of the will. It is not moved by another, not even by the intellect. Metaphysically speaking, the affectio commodi is like a nature and the affectio justitiae is like a will. In this way, Scotus preserves the traditional Aristotelian notion that the will operates as a nature and is moved by another, but also preserves the radical liberty necessary for moral action and accountability.
 Allan B. Wolter, Duns Scotus on the Will and Morality (Washington, DC: Catholic University Press, 1986), 37.
 “There is no other cause to be found except that the will is the will.” Questiones Metaphysicam 1, q. 15, a. 2; trans. Allan B. Wolter, Duns Scotus on the Will and Morality (Washington, DC: Catholic University Press, 1986), 153.