I have been assuming that there are mental acts and that there are mental actions and that they must not be confused. It's high time for a bit of exfoliation. Suppose I note that the front door of an elderly neighbor's house has been left ajar. That noting is a mental act, but it is not an action. I didn't do anything to bring about that mental state; I didn't decide to put myself in the state in question; I just happened to see that the door has been left ajar. There is nothing active or spontaneous about the noting; it is by contrast passive and receptive. But now suppose I deliberate about whether I should walk onto the man's property and either shut the door or inform him that it is ajar. Suppose he is a cranky old S.O.B. with an equally irascible old dog. I might decide that it's better to mind my own business and "let sleeping dogs lie." The deliberating is a mental action. So, assuming that there are mental acts and assuming that there are mental actions, it seems as clear as anything that they are different.
Why then are mental acts called acts if they are not actions? It is because they are occurrent rather than dispositional. Not everything mental is occurrent. For example, you believe that every number has a successor even when you are dead drunk or dreamlessly asleep. This is not an occurrent believing. Indeed, you have beliefs that have never occurred to you. Surely you believe that no coyote has ever communicated with a bobcat by cellphone, although I will lay money on the proposition that you have never thought of this before. You believe the proposition expressed by the italicized clause in that you are disposed to assent to it if the question comes up. So in that sense you do believe that no coyote, etc.
Mental acts are so-called, therefore, because they are actual or occurrent as opposed to potential or dispositional. My noting that the old man's door has been left ajar is an occurrent perceptual taking that is not in the control of my will. As Wilfrid Sellars points out,
It is nonsense to speak of taking something to be the case 'on purpose.' Taking is an act in the Aristotelian sense of 'actuality' rather than in the specialized practical sense which refers to conduct. A taking may be, on occasion, an element of a scrutinizing -- which latter is indeed an action in the practical sense. To take another example, one may decide to do a certain action, but it is logical nonsense to speak of deciding to will to do it; yet volitions, of course, are mental acts. (Science and Metaphysics: Variations on Kantian Themes, Humanities Press, 1968, p. 74.)
Another example Sellars cites is drawing a conclusion from premises. That is a mental action, but there are mental acts involved in this will-driven thinking process. One is the 'seeing' that the conclusion follows from the premises. It cannot be said that I decide to accept a conclusion that I 'see' follows from certain other propositions. The will is not involved. The 'seeing' is a mental act, but not a mental action.
Gustav Bergmann says essentially the same thing. "An act is not an activity and an activity is not an act." (Realism: A Critique of Brentano and Meinong, University of Wisconsin Press, 1967, p. 153.) He says that this was crystal clear to Brentano and Meinong, but that in the Aristotelian-Thomistic tradition 'act' carries an implication of activity. "In the Aristotlelian-Thomistic account . . . an act of perceiving is the 'abstracting' of a substantial form; and an 'abstracting' is an activity." (Ibid.)
Very interesting. It sounds right to me, though I wonder if all Thomists would agree. Not being a Thomist, I incline to the later view. So as I use 'mental act' a mental act is not a mental action or activity. This is of course consistent, as already indicated, with its being the issue of certain mental actions.
A deeper and more important question is whether there are mental acts at all. Their existence is not obvious -- or is it? Wittgenstein appears to have denied the existence of mental acts. Bergmann believes he did, while Geach believes he did not. There is also the related but distinct question whether mental acts require a subject distinct from the act which remains numerically the same over time. But is even a momentary subject needed? Why couldn't awareness be totally subjectless, a "wind blowing towards objects" in the Sartrean image? Butchvarov takes a line similar to Sartre's.
Clearly, there has to be some distinction between conscious intentionality and its objects. That's a rock-bottom datum upon which "our spade is turned" to borrow a phrase from old Ludwig. But why must consciousness be articulated into discrete acts? Why believe in acts at all? What are the phenomenological and dialectical considerations that speak in their favor?
Future posts will tackle all these questions as we plunge deeper into the aporetics of mind and bang into one impasse after another. It should prove to be a humbling experience.