René Descartes believes that he is sitting by the fire in a dressing gown. Presumably, he has this belief because this is how things are presented to him by his senses. However, Descartes reasons, things could appear to him just as they do even if he were in fact not sitting by the fire, but were instead sleeping or mad or the victim of a deceiving demon.
He proceeds to remind the reader of the definition of virtue epistemology. Virtue epistemology alters the classic definition of knowledge as true, justified belief in an effort to exclude true beliefs which are justified but nevertheless arrived at accidentally or through deception. Instead, virtue epistemology suggests that knowledge is true belief which is arrived at through intellectual virtue. Only when the true belief is reached through the right exercise of reason is it truly knowledge. With this, Greco answers Cartesian skepticism.
…to say that someone has an ability to achieve X (hitting baseballs, for example) is to say that he would be successful in achieving X in a range of situations relevantly similar to those in which he typically finds himself. But then possibilities that do not de no occur in relevantly similar situations…do not count in determining whether a person has some ability in question. For example, it does not count against Babe Ruth’s ability to hit baseballs that he cannot hit them in the dark. Likewise, it does not count against our perceptual power that we cannot discriminate real fires from demon-induced hallucinations. Accordingly, virtue theory explains why our inability to rule out Descartes’ possibility of a demon is irrelevant to whether we have knowledge. Namely, knowledge is true belief grounded in intellectual virtue. The fact that our intellectual faculties would be unreliable in world where demons induce perceptions is irrelevant to whether they count as epistemically virtuous in the actual world.
There are two problems with this argument, and the first ought to be obvious. It is by no means self-evident that demons do not induce incorrect perceptions in the accurate world. The assumption that they do not and that the problem may be therefore dismissed as theoretical represents a bias which Greco enters the argument with. Even if he does not believe that demons actively deceive people, he lacks the epistemic tools to prove definitively that they do not. I doubt that Descartes would have been very much convinced by the argument, “That’s all well and good, but demons do not in fact possess people in the actual world.” What is even more galling, is that this line of reasoning only applies to the possibility of demon possession. Certainly Greco would not suggest that in the actual world people do not in fact sleep or go mad. If our intellectual faculties are admitted to be unreliable in a world where we sleep and go mad, then that is very relevant given that in the actual world we both sleep and go mad.
It may, of course, be objected that when we sleep or go mad (or even are possessed by demons) that we lack the intellectual virtue that is a prerequisite for knowledge. While that may very well be true as a theoretical way for ordering reality, there is a problem with applying it practically. The evaluation that Descartes is sleeping is only possible from an exterior standpoint. For Descartes, who is concerned with his own ability to know whether or not his perception is reliable, he is impotent to accurately deduce whether he is sleeping or not. Certainly those who are mad would be the last to admit that they lack the epistemic virtue necessary to possess knowledge. It may be nice for Greco to be able to point to an asylum and say that virtue epistemology explains why the true beliefs of the inhabitants are not knowledge while his is, but as the knowing agent he is actually incapable of demonstrating that he is not in fact in that asylum being pointed at from without by those he believes are inmates.
What is left is an epistemology which is sound in theory but no more immune to the problems of skepticism in practice than any other theory of thought.