 Scotus argues that the human intellect is capable of achieving certainty in its knowledge of the truth simply by the exercise of its own natural powers, with no special divine help. He therefore opposes both skepticism, which denies the possibility of certain knowledge, and illuminationism, which insists that we need special divine illumination in order to attain certainty. He works out his attack on both doctrines in the course of a reply to Henry of Ghent in Ordinatio 1, d. 3, pars 1, q. 4. (For a translation, see van den Bercken [2016], 114–143.)