Aristotle’s principle “Obiecta sunt praevia potentiis” is what most divides him from the “Enlightenment” philosophers.
Western philosophy since Francis Bacon (if not before) could be seen as an attempt to found one’s theory of reality upon the theory of knowledge. All of them, from Descartes’ “evil god” to the Kantian critique begin by doubting the objects which one thinks about because of doubts about our power of knowing. Then, once they have settled on the limits of knowledge, they begin to make their physical and metaphysical claims about the nature of reality: a process which seems inevitably to lead to Kant’s denial of knowledge of things in themselves.
But one might critique this view in the following way: thoughts about things relate to the things thought the way that thought about thought relates to thoughts thought. Or, to say the same thing in another way, thought about thought is thought about a thing: thought. Thus, if things are unintelligible wouldn’t thoughts be unintelligible a fortiori? Thought about thought presupposes and, as I will argue, is dependent on thought about things.
To make this point, consider sight: I know that I see, but how do I know that I see? Don’t I know that I see precisely because I have seen? Can I know that I am seeing when I am not seeing anything? Similarly, it could be asked: how do I know that I know? The answer seems to be precisely the same as for sight: I know that I know because I have known. Thus, to speak generally, apprehension of apprehension depends on the prior (in nature as one is prior to two, not the priority of time) occurence of apprehension.
That this is so can be seen in the videos of patients in comas who respond to sensory stimulus without, seemingly, being aware that they are sensing: in a particularly apt example, the patient was told to respond to a question by imagining one activity to signify “yes” and another to signify “no.” When a question was put to him, brain scans indicated that he had said “yes.” What, then, is the difference between him and a person not in a coma? Assuming that his motor pathways were functional, it seems to be precisely the fact that he hears and responds to sounds without realizing that that is what he is doing.
An even more dramatic confirmation of the thesis that apprehending is prior to apprehending apprehension can be gathered from the phenomena of “Blindsight.” Wikipedia relates the following occurence:
In 2003, a patient known as TN lost use of his primary visual cortex, area V1. He had two successive strokes, which knocked out the region in both his left and right hemisphere. After his strokes, ordinary tests of TN’s sight turned up nothing. He could not even detect large objects moving right in front of his eyes. Researchers eventually began to notice that TN exhibited signs of blindsight and in 2008 decided to test their theory. They took TN into a hallway and asked him to walk through it without using the cane he always carried after having the strokes. TN was not aware at the time, but the researchers had placed various obstacles in the hallway to test if he could avoid them without conscious use of his sight. To the researchers delight, he moved around every obstacle with ease, at one point even pressing himself up against the wall to squeeze past a trashcan placed in his way. After navigating through the hallway, TN reported that he was just walking the way he wanted to, not because he knew anything was there. (de Gelder, 2008)
In this case it seems manifest that the person was blind, not because he did not see, but because he did not realize that he saw.
This example also shows that consciousness is not merely sensation: for an activity to be conscious, it must be reflected upon. Thus, it is clear that it presupposes knowledge of reality. Consequently, Aristotle’s method seems better than the modern method since it respects our order of knowing: first we know things and then our knowledge of things. Thus, the De Anima where Aristotle discusses our knowledge is not placed at the beginning of the course of studies, but towards the end since it presupposes knowledge of things.