Husserl considers phenomenology a kind of meta-theory of knowledge. He claims that a theory is not a bundle of sentences or observations. It is a rule- based connection of propositions obtained by inductive or deductive methods as well as a model of the domain of its objects (1900/1901). Philosophical or scientific theories have theoretical and ontological primitives that are not derived by arbitrary construction. The primitives and the operations admitted on the propositions are meaningful if they specify the features and the structure of the objects, however abstract or even formalized they may be. Therefore, the meta-theory is itself a theory. If concepts and methods are constructed all of a piece with the domain model, the phenomenology is the theory of the fundamental source of evidence in which the phenomena are given within the limits of their relevant inherent characteristics according to the general “principle” that
every originary presentive intuition is a legitimizing source of cognition, […] everything originarily […] offered to us in “intuition” is to be accepted simply as what it is presented as being, but also only within the limits in which it is presented there. ( 1983: 44)
Thus the construction of a theory is autonomous with respect to extraneous philosophical or scientific assumptions. In this section the scope of these issues is restricted to perception, hence the phenomenology is intended as one theory whose concepts and primitives refer only to the characteristics of perceptual reference and the features of appearances in order to study the phenomena relevant to any theory of perception. Thus it is possible to understand the forms of the theories of perception, namely their theoretical and ontological primitives, at the level of abstraction required by the method of research, and to retrace their meaning to relevant phenomena. As pure, empirical and applied sciences are constructed on the grounds of the same phenomena, so there can be theories of perception at various levels of abstraction. Husserl (1911, 1916) outlines a bottom-up reconstruction according to which a theory arises from the less abstract one by replacing its primitives and method starting from the “natural world” of perceptual experience. The phenomenology is constructed as a pure theory of perception that recovers the features and structures that are implicit in the natural world and implied by the other theories of perception (for a different, top-down approach, see 1913; infra § 7.2).
The “natural world” is the context of the ordinary experience in which perception takes place. In fact it also contains non-perceptual material and cultural constituents. It is the environment where things and events appear, but also where goods and values are experienced, although always on the grounds of the perceptual properties of things, and where subjects behave guided also by practical habits as well as popularized scientific knowledge (1911, 1913). Nonetheless, Husserl maintains that perception can be isolated from this network of intertwined activities and objects and captured by descriptions that show its epistemological characteristics and how consistent it is.
In naive experience, the subjects mean to perceive the things in the environment, even if this does not mean that perception lacks a mediating structure whose account is the aim of the theory. Indeed, they recognize that they can actually be deceived in perceiving things, but also acknowledge that this is the case because of inaccurate appearances that are misleading in comparison to more accurate perceptions that come about later. In this sense, the perception implies the belief character of certainty, which is not associated with the assumption of a physical cause, as in Brentano’s account, because it refers to the thing that is preserved as the same through the manifold appearances despite the changes they undergo. Moreover, the appearances have to imply also a possible connection with one another for perception to modify the belief character from being deceptive or dubious to being certain or real (1913, 1939). For instance, it makes sense to say that someone sees a circular object erroneously as elliptical only if the appearance of an elliptical shape is replaced in an ordered way by appearances of an increasingly circular shape as she and the object move towards each other, while the colors, localization and spatial relation of the object to its surroundings remain the same. Husserl emphasizes that this connection between manifold appearances enables subjects to exploit the perceptual errors or illusions as clues to gain a more accurate understanding of the actual state of affairs.
The perception in naive experience is described as the regular course of appearances. This description provides the empirical basis on which the theories of perception build their primitives. Experimental psychology replaces the perceptual appearances with the primitives and variables of the natural sciences to treat them as states that depend on processes of the sensory organs localized in the space and time of physics restricted to physiology (1916). Experimental psychology accounts for perception through a theory of the causal basis of the sensory-specific response capacity. However, the theory may build the explanation at a more abstract level if it aims at accounting for the epistemological questions of perception. The physical and physiological constructs are introduced insofar as they give rise to the sensations that are considered equivalent to phenomenal proxies of external material things.
Husserl (1911) contends that as empirical geometry becomes pure geometry, when spatial forms are abstracted as “limit forms” from the properties of existent things, so experimental psychology may become a pure theory of perception. The forms of perceptual reference and appearances are abstracted from ordinary perception as an autonomous object of research that is distinguished from the causal and physiological conditions of perception. Husserl cites Brentano’s descriptive psychology as a clear example. Just as the study of possible deformations of spatial figures may replace the study of bodies’ transformations due to existent causes, the pure psychology of perception may describe the possible features of perceptual reference and appearances and the forms of their possible connection.
Husserl maintains that a theory of perception can be constructed at two higher levels of abstraction. As pure geometry and kinematics become theoretical sciences if they deal with the varieties of the forms of space and motion independently of the actual or possible instantiation in our world, descriptive psychology becomes pure phenomenology if an actual or merely possible appearance is considered an index of a manifold of perceptual features and connections that are variable at will. In general, for any appearance X one is free to modify it by applying arbitrary transformations to every respect contingent on the space-time and the causal relations in which X may occur. Thus indefinitely many appearances are obtained, which progressively differ from X in one respect. They can be interpreted as copies of X in arbitrarily different worlds so that each appearance is a variant of X given some transformation. Though the multiple variants differ from X to increasingly arbitrary extents, they are not an aggregate of distinct appearances, rather parts of a manifold ordered according to the degree to which they are congruent to one another under the respect that is preserved across the transformations. This congruent feature is the invariant of X that qualifies its essential nature, that is, the structure $ that all the appearances like X share as the constraint of its multiple arbitrary variants taken at the limit of the free variation. For example, a color appearance can vary along three dimensions: (1) as a specimen of a color; (2) as a shade of color, like vermillion, scarlet, crimson and so on belong to the series of red; (3) as an arbitrary color, that is, any appearance whose alterations performed at will bring about variants, to which hue, brightness and saturation belong along with spreading over a surface. Husserl maintains that any appearance is specified by the values it takes along these dimensions that form the manifold of the color structure and at the same time of the possible color perceptions.
Finally, Husserl (1911) claims that it makes sense to conceive of worlds with different phenomenal properties for subjects with a different nature and evolutionary history than ours. Yet perception has to show coherence and consistency to satisfy its function of enabling subjects to have access to the world. However different they may be, the appearances cannot be unrelated snapshots of things or amount to a contingent aggregate of qualities. They depend on a vantage point with the admitted transformations so that anything perceivable is bound to appear from this or that side, but always in one of its possible aspects. This means that what is perceived has qualities and changes whose appearance is indexed in relation to the distance, the orientation, the location and the state of rest or motion of subjects, but is also connected to the indexes of earlier or further appearances. Appearances always come in series, and the reference to the thing is composed of the phenomenal contribution of each appearance in the series. Thus a more abstract phenomenological theory aims at specifying the laws of perception that have as analogous a role as the abstract categories of semantic rules and syntactical categories of language. By arbitrarily varying the transformations of the standpoints and the qualities of appearances, the theory derives the features and connections whose absence or derogation show that a law has been violated, in the sense that the appearance would be not only an error or an illusion, but meaningless or nonsensical. In the first case, the violation reveals the laws regarding the coherence of the qualities of appearances that are integrated in the same thing as well as their compatibility with the surrounding things (Husserl, 1918-1926). In the second, it reveals the laws of consistency among the changes of the standpoint and those of the appearances. In this case a deviating perception is equivalent to an ill-formed string of symbols that violates a syntactic rule, rather than a sentence with no meaning. At this level of abstraction the theory treats the perceived things as open-ended systems of manifold appearances that converge to a value x, which are correlated to specific rules of perceptual reference (Husserl, 1913; Gurwitsch, 1964). Husserl ( 1989: 91-92) states indeed that
the thing is a rule of appearances. That means that the thing is a reality as a unity of a manifold of appearances connected according to rules. Moreover, this unity is an intersubjective one […] The material thing is intersubjectively common in that it has validity for all individuals who stand in possible communion with us (translation partially modified).
Across Husserl’s distinctions the implications of the phenomenological theory remain important for any theory of perception. Husserl (1913) claims that the knowledge of abstract structure is related to the knowledge of less abstract domains like the structure of color is related to any color instance. It is not necessary to know what being a color means to perceive a color. Still, any appearance implies the invariant properties of color. Likewise, philosophical or experimental research need not imply phenomenological analysis, but if theories and discoveries are correct and true to experience their content is consistent to and might be developed in phenomenological terms. Therefore, scientific explanations do not depend on phenomenology. On the other hand, phenomenology is not separated from the scientific account of ordinary perception, just as a meta-theory of the form of theories is still a scientific theory. Spiegelberg (1972: 70) emphasizes that Husserl conceded that phenomenological propositions can be integrated by evidence of experimental research and cites Wertheimer (1912a) as an experimental test case for the phenomenology of motion perception (cf. Embree 1979). Katz (1930: 30) argues that the phenomenology was essential to his research into color perception (infra § 3.3).
Source: Calì Carmelo (2017), Phenomenology of Perception: Theories and Experimental Evidence, Brill.