  Scotus’s own view is that the human mind is capable of such knowledge on its own. If by “certain and pure truth” Ghent means “infallible truth, without doubt and deception,” then Scotus thinks he has established that human beings “can achieve this, by purely natural means” (Ord. I.3.1.4 n. 258). How can such a thing be established? How can the skeptic be refuted, without appealing to divine illumination? Scotus distinguishes four kinds of knowledge: