Université de Perpignan

In the next section we will formalize Peirce's elementary perception theory in terms of relational algebraic structures. We require an empirical base for our attempt to create a model of the process of acquisition, memorisation, representation and communication of knowledge. For that we must take into account in one way or another the essential nature of human experience: the fact that man's relationship to the world around him comes through his perceptive faculties. Because his knowledge is determined by his perceptions, whether it comes through direct perception of the physical world or through the perception of non-physical reality transmitted through "signs" in the physical world, the forms this knowledge takes depend on the forms of the perception itself.

   Therefore, a scientific approach to the question must either adopt and integrate a theory of perception in its development, even in embryonic form, or justify its independence of the nature of perception. We are in favour of the first possibility. We will consider the results of Peirce's "abstractive observation" of what he calls a "percipuum" [8,CP7-629],3that is to say a singular fact of perception. Peirce analyzes it as being the juxtaposition of a percept and a perceptual judgement. The percept is the simple sensation and the perceptual judgement is the fitting of that sensation into a structure of sensations. This is in concordance with concepts commonly accepted today concerning perception, which is described as a process in which the subjects not only choose the elements of the percept, but also the way in which they should be arranged in order to constitute the perceived whole. These simple "qualities of feelings" are directly produced by stimuli coming from the world outside and they are selected according to their "pregnance" and "forcefulness"-that is to say according to the subject's more or less developed receptivity based on his previous experiences or on the natural capacity of the stimulus to impose itself on the subject's perceptions by its own power. Perceptual judgements are produced in the subject's own interior world and in essence they consist of bundles of qualities of feeling which constitute a sort of unit of a superior order.

   Such units form semantic nets. J. F. Sowa [9] explains it as "a conceptual graph which describes the way percepts are assembled." In visual perception, for example, the existence of ambivalent images proves that a single percept (a single group of qualities of feeling produced by an image as a source of visual stimuli) can be arranged by two distinct perceptual judgements, and because of this can generate two distinct mental entities. Accordingly, sets of qualities of feeling on the one hand, and bundles of these qualities of feeling which are linked together by a complex group of relationships on the other hand, will be our empirical universals associated with perception phenomena.

   One can consider that all perceptual judgements occur as families of uninterpreted n-adicpredicates of which the blanks (or place markers) are occupied by the simple qualities of feeling.These will be taken into account in our model as an abstract set sufficiently large to allow all the qualities of feeling present in a given perceived fact to be identified with interrelated subsets of the "big set" or power-set 2n of all possible combinations of n qualities of feeling. All sets taken into consideration in what follows will be such subsets. The perceptual judgement which organizes and arranges them can be made to correspond perfectly with the mathematical definition of relational structure as given below.

3References to CP are followed by volume and paragraph numbers; they refer to The Collected Payers of Charles S. Peirce.