On Franz Brentano, The Distinction between Mental and Physical Phenomena (1874)
1.
“All the data of our consciousness are divided into two great classes—the class of the physical and the class of mental phenomena. […] But what we have said is not sufficient. […] [S]ensation and imagination are distinguished by the fact that one occurs as the result of a physical phenomenon, while the other is evoked by a mental phenomenon…. But … what appears in sensation does not correspond to its efficient cause. Thus it turns out that the so-called physical phenomenon does not actually appear to us…!”
2.
This passage from Brentano’s book, Psychology from an Empirical Standpoint, is the beginning of his delineation of the problem that had been troubling psychologists and philosophers for years on the nature of how the individual consciousness contains conceptions of and understand relations of things within the world at large. From the first premise, that all conscious data are divided into two classes, Brentano goes on to set out the problems that had theretofore afflicted scientists and philosophers of mind that had attempted to defend such a position. An example of this problem is the contradictory statements that scientists had been forced to make regarding imagination and sensation: though the two were purported to be separate phenomena, one physical and one mental, it had been shown that the efficient causes of sensations—objects in the world—did not always correspond to what was actually perceived, and that indeed things could be mistaken for other things—the sensations admitted to confusion.
Brentano goes on to talk about the different possible answers to this question of the fundamental difference between mental and physical phenomena, until finally settling on the notion that mental phenomena are characterized by “intentional inexistence,” that is to say, by being about something else.
3.
Beginning with a statement of purpose to clarify the difference between mental and physical phenomena by making the definitions and descriptions of each more specific instead of (what he seems to think would be) taking the easy way out and making the descriptions even more generalized, he posits that the idea or “act of presentation” to the consciousness an object of experience in the world is a mental phenomenon. That is, not the object in itself, but that which the mind takes from the efficient cause of a sensation. Furthermore, judgments, beliefs, all emotions, and all recollections are examples of mental phenomena; whereas, physical phenomena are colors, figures, and other such “sensible” objects of experience.
From that point, seeking a more “unified definition” of the difference between the two types of phenomena, Brentano brings up the idea that Descartes, Kant, and others put forth, that the defining feature of mental phenomena is that they do not share with physical phenomena being extended into space and having location. However, he notes, people object that some physical phenomena have no extension, and others that mental phenomena do in fact.
Ultimately he arrives at the Scholastic notion of the intentional inexistence of mental phenomena, their being about something. This aboutness characterizes mental phenomena, argues Brentano, is never shared by physical phenomena: colors and figures, chords and states of heat or cold are not “about” anything in the way that judgments, beliefs, and emotions are. He answers the objection that feelings of pains, like cuts and burns, are not intentional by saying that there are always presentations to our minds, even when we are dealing directly with stimuli within our own bodies. There is always a presentation involved, when the mind is involved; the mind is always directed toward something, and thoughts are always about their objects, even if they do not correspond perfectly with external objects (efficient causes of the presentations).
Brentano goes on to defend other aspects of this theory, such as that mental phenomena can occur simultaneously whereas physical phenomena can only occur serially; and that mental phenomena are only conceived of in the inner consciousness, not externally. Later psychologists would contest various aspects of Brentano’s theory, but it remains highly influential in the field.
