Los ingredientes de la percepción

Abstract

We shall undertake an analysis of perception and what is perceived, that is of the act of perceiving and the perceived objects.

The first step in this analysis will be to justify the above mentioned distinction showing that the act of perceiving and the perceived object are two different kinds of existents. The independent existence of each other, i.e., the fact that one of them could possibly occur without the occurrence of the other, would be a sufficient criterion to establish such a distinction; but this criterion is not applicable in the present analysis, given that it is not possible to have a perception without an object of perception, nor the other way round, even though it may be possible to have an object without a perception. A second criterion refers to the modal differences between the two items we are considering here. The application of this criterion allows us to distinguish between that which is perceived, a physical phenomenon, and the act of perceiving, a mental phenomenon. This distinction implies several consequences with respect to the characterization of each of them.

What has been said, up to this point, does not necessarily means that perception and that which is perceived could not possibly be analyzed and reduced to some other more elementary phenomena. But before any analysis is undertaken, one should describe both phenomena. This should begin with a description of that witch is perceived.

In order to proceed according to the rules of the phenomenological method, let us choose the case of an object of perception which is being simultaneously perceived by all those people who are, supposedly, now in this room: this table. When one utters those words people who are in this room direct their attention to this table, and by doing that, they are detaching the table from other possible objects of perception and placing it in the middle of a perceptual field. An object of perception is never perceived in absolute isolation from a field of other similar objects of perception, unless the field of perception itself is that which is being perceived. The perceptual field —whether it is just the background against which we detach the object of perception, or the perceived object itself presents a peculiar complexity: as afield of perception, it is itself constituted by the simultaneous objects of perception of all the sense organs. These partial objects of perception which constitute the whole field of perception, do not have the same sort of relations among themselves; for example, the visual objects of perception appear within a visual continuity, whereas the tactual ones are within a tactual discontinuity, sounds may be encased either within a visual continuity or within a tactual discontinuity, and so on. But amongst all these relations the most important are those which hold between the perception of one's own body and the rest of the field of the perceived objects.

For each one of us, the body is a visually perceived object which is constituted by all those parts of its surface which one can see at a time; but one's own body is more specifically a tactually perceived object. One's own body, as a visually perceived object, occupies the extreme end of the visual field from which the detached object together with the surrounding field is perceived. When one shuts one's eyes the visual perception of one's own body disappears, and basically we are left with no more than a tactual perception. This may become the end point from which an image of the field of those visually perceived objects —those that were being perceived before shutting one's eyes extends. What all this means is that the perception of one's own body seems to be a condition for the perception of any other object. It also makes it clear that the sense organs, although parts of our own bodies, are but partially perceived visually as such: they constitute objects of perception in other, and furthermore, they seem to be genuine objects of theory.

There is something still more important than all that has been said up to now, and this is that the whole field of perceived objects, within which is included the perception of one's own body, is a perceived object for each one of us, that is, it appears in its turn to each one of us as an external object. One's own body is an object of perception as external as any other perceived object. The relation between someone and his own body is not a relation of inwardness nor of outwardness these two are expressions coined to describe a different kind of relation, that is, the relation of presence or intentionality.

Here we are faced with the following problem: how is such a presence of our own body (which is a physical phenomenon) to the mind possible?

I have been talking about our own bodies to call the attention to the fact that the perception of one's own body is, to each one of us, as subjective as the phenomena of one's own consciousness. We must notice here that one's own body seems to be an exception amongst all other physical phenomena which in all other cases are intersubjective. My neighbor's body, for example, is an object of perception as intersubjective as any other object of perception. This Is not the case with my neighbor's mental phenomena which only have a partial intersubjectivity. But, are the objects of perception in general really intersubjective, in an absolute sense?

Are there no differences between our perceptions of this table? There are some intersubjective elements in our perception of this table. We all agree, for example, in that it has a rectangular shape, but there certainly are some other subjective ingredients in it which could only be discriminated by analysis.

Sometimes we perceive an object from such a distance that we do not perceive it in all its detail. If we were to approach it we would see it perfectly clearly. Then if we went back to the same point from where we had perceived it for the first time, we would be able to see more details than upon the first occasion. The perception of an object from a close distance leaves images in us which allow us to perceive, when we see it again from a long distance, what we did not perceive in it the first time we saw it. This means that what we perceive from a long distance is constituted by images which complete the rest of the perceived object.

A perceived object is constituted, in addition, by some other ingredients. What we perceive is necessarily either a substance, or a mode of one or several substances. But, being a substance or being a mode, i.e., the substantiality or the modality themselves, are not images but rather ideal objects. They are relations which inform or constitute what is perceived, i.e., the perceived objects. Therefore, a perceived object is integrated by images, relations and that which is completed by images and informed by relations. Still more, perceptions are also integrated by mental states and movements of the perceiver, not only by affective motions but also by impulsive and volitional ones. In short, perceptions are integrated by images, relations, affective and active motions and emotions, and by that which all these ingredients come to complete, which are the sensory, sensitive, elements, i.e., the perceptive elements structusensu. These elements, which are usually denoted by the term "sensations", show all the differential characteristics of the objects of perception. These characteristics are not found in the images, nor in the relations, nor in the motions and emotions.

The next step in this study is an examination of the relations between sensations and all other ingredients which constitute that which is perceived. We have been saying that any object of perception —including the one of the whole field of perceived objects at each momentis a compound integrated by sensations, completed by images, informed by relations and felt with particular emotions and the associated movements. It seems necessary now to clarify these relations and to give an account of them in adequate terms. The relation which holds between sensations and images is that of continuity between the same sort of elements. The relation holding between sensations and relations is a relation between so heterogeneous terms that it can only be put into words by means of figurative expressions. Finally, concerning the relation between sensations and emotions, one could only mention here that it has to do with the participation of motions and emotions in objectivation.

Now, sensations are elemental physical phenomena, while other ingredients of perception are of a mental or ideal nature. Given that we cannot doubt the physical nature of that which is perceived, nor the mental nature of emotions, we must accept that sensations are the basic physical phenomena of perception. Images are but traces left by perceptions and so they cannot serve as an explanation of perception; it is rather the latter which must explain images. Thus we are only left with sensations as candidates to wear the characteristics of physical phenomena. This argument is complemented by two others: the first one showing the characteristics of physical phenomena and of sensations; the second one providing an explanation of why sensations are falsely conceived as mental phenomena.

Sensations are the sensible qualities themselves of what is perceived, thus, for example, the colour of this table is —"sensorily"— nothing more than the continuity of colour shades which in themselves are nothing more than a set of chromatic sensations. These latter are fundamental constituents of this table as a perceived object. The reasons why the intersubjectivity of what is perceived and the subjectivity of sensations are not acceptable, in general, are, briefly: (1) that sensations are subjective; (2) the intersubjectivity of what is perceived is due to the concepts of relations and modes, in general, which contribute to integrate it; (3) the partial nature of the intersubjectivity in that which is perceived is due to the complex relations between objects of perception and perceivers. Taking once again our example of the perception of this table, we shall see what would happen if each of us tried to draw a coloured sketch of it. All the sketches would be different according to the different angles from which they were drawn and to the different conditions of illumination corresponding to each angle of perception at the same moment. Those who know how to make a sketch will draw the shape and colours they can really see; those who do not know how to make a sketch will draw the shapes and colours they know the object to have; and this will be the case even if we do not take into account those differences which are conditioned by the location and light conditions of the object. The rectangularity and the uniform grey of the table cannot be properly said to be seen by us, in the same way as the different angles of the object and the variety of grey shades are grasped and reproduced by the skilled painter. The rectangular shape and the uniform grey are perceived because they are thought of with the corresponding concepts "rectangular" and "grey" which are used in this case. What is intersubjective are just the concepts of rectangularity and greyness. On the contrary, the different shades of the colour grey and the different angles of the table are that which are experienced differently by each one of us, Le., they are subjective. The intersubjectivity of that, which is perceived, is thus partial. The degree of intersubjectivness of the objects of perception varies according to: (1) the number of perceivers which are perceiving at the same time, within certain spacio temporal limits, the object in question, and (2) according to the concepts and other ingredients which integrate and condition perceptions. The conclusions we have reached up to this point, allow us to state that subjectivity and intersubjectivity do not constitute an essential difference between physical and mental phenomena. Sensations —which are elementary physical phenomena— are subjective like any mental phenomenon; on the other hand, that which is perceived —a compound of physical phenomena— is intersubjective, and this is so not because of the physical elements, but because of the concepts and modes which integrate and condition it. Sensations do not occur within consciousness, but rather within the objects of perception for the consciousness, and they turn out to be intersubjective because of the intersubjectivity of concepts. The expression "for the consciousness" denotes very precisely the fact that sensations are compounded by relations and are either causes or effects of motions and emotions or of their intentional objects. Finally, the fact that sensations —and by means of them perceptions— are present to the mind is an ultimate and indescribable phenomenon; strictly speaking this phenomenon can only be intuited: it is a modality of the relation between something physical and something mental. The expression "physical phenomenon" means nothing more than a peculiar kind of presence, which constitutes sensations and, by means of the latter, the objects of perception.

This, I think, is enough for an analysis of that which is perceived. As for perception itself, Le., the act of perceiving, this is nothing more than a compound of motional and emotional acts of the perceiver and of the act of conceiving those relations which contribute to integrate that which is perceived. The mental characteristics which differentiate the act of perceiving from that which is perceived –with all its physical characteristics— belong to those acts. Therefore, one can say now that there is an act of perceiving different from that which is perceived.

Up to this point, we have been doing nothing more than a phenomenological analysis of perception. Now, we shall try to say something about the metaphysical theory of perception: the theory of the subjectivity of sensory qualities (primary and secondary) together with the theory of the perceptibility of the physical matter. Secondary sensory qualities, such as colours, as well as the primary —which are spatial are appearances caused in the consciousness by external physical matter, but, on the other hand, they are subjective. This physical matter —atoms or waves, or a magnetic field or what not— is perceptible on principle. Its actual imperceptibility is something accidental, it is the result of the lack of instruments to help our sense organs to perceive it.

If, and only if, one accepts that sensory qualities are appearances caused to the consciousness by physical matter, may one understand phenomena such as the expansion of gases or the propagation of light. If, and only if, physical matter is perceptible, may one understand that it is the cause of physical phenomena. What we mean by "understanding" in such biconditional sentences, is that one can imagine a model, i.e., a set of non-perceived objects, which would behave according to the pattern of perceived objects —inverting the relation of a model to that of which it is a model. But, some authorities claim that the idea of a model is being abandoned in physics, so that there will remain just a mere mathematical formulation of phenomena since these behave in an unimaginably complex way. This would mean that scientific thought is ceasing to conceive metaphysical physical objects, or at least ceasing to think of them as necessary for the explanation of physical phenomena. In any case, it would be a contradiction in terms to say that physical objects, which are the cause of physical phenomena, are at the same time physical phenomena. The two theories which have been traditionally linked together are actually contradictory.

If sensations were mental phenomena, what has been said up to now, would imply the need to accept "empirical idealism". But if we take sensations to be physical phenomena, this is enough —even if there is nothing more than phenomena to reject the idea that everything can be reduced to what is mental in the subject.