It was generally agreed in the Middle Ages that we perceive the acts of our own soul. When seeing a stone, say, we normally perceive the seeing and not only the stone. There were, however, disagreements concerning how this second-order perception ought to be understood and whether it is separable from the first-order seeing. Already Augustine recognized the implicit infinite regress resulting from perceiving the act by which one perceives one’s own perceptual act, and welcomed it as showing even to the skeptics that we know not just something but an infinity of things, but the medieval authors did not take the infinite regress as a refutation of a theory involving second-order mental acts. William Ockham, for example, remarks that infinity is beyond human capacities. One perhaps can have a third-order perception of the perception that one sees, but further levels of perception maybe beyond the reach of the human mind.
Medieval authors often took up as a separate question whether habits or dispositions of the soul can be directly perceived. Normally, the answer is that they are perceived through acts of the soul.
As a part of his theory of intuitive cognition, John Duns Scotus took the view that we have indubitable knowledge of our own mental acts, because we perceive them directly and immediately. In his own theory, William Ockham made it clear that we perceive our own mental acts by second-order acts - that there are no literally reflexive acts which would not be directed at objects. These second-order acts are reflexive in the looser sense that they have first-order acts as their objects, thus yielding intuitive, certain knowledge of one’s own mental acts.
Walter Chatton criticized Ockham’s theory and claimed that all perceptual acts are experienced already through their presence in the soul. No second-order act would thus be needed for the first-order act to be experienced. Ockham, and his disciple Adam Wodeham, answered by making it clear that nothing can be experienced without a mental act taking it as an object, and interestingly pointed out that not all mental acts are conscious. Thus, if one sees a stone on a narrow path (and does not stumble on it), one notices and knows that one sees the stone only if one has a second-order act directed at the first-order perception of the stone. Thus, one must recognize the class of mental acts that remain nonconscious. Wodeham even presents the interesting case of a person thinking that he does not think. Otherwise, the examples found in the discussion are parallel to examples used in twentieth-century philosophy like stopping at red lights without noticing that one has seen any traffic lights.
See also: > Adam Wodeham > Augustine > Ibn Rushd, Muhammad ibn Ahmad al-Hafid (Averroes) > Ibn Sina, Abu 'All (Avicenna) > Intentionality > John Duns Scotus > Matthew of Aquasparta > Peter John Olivi > Thomas Aquinas > Walter Chatton > William of Ockham
World History
