(…)
We had to accept that we could recognize living systems when we encountered them, but that we could not yet say what they were.
(…)Yet I obviuosly had some inkling of what the correct answer were, because I rejected the unsatisfactory ones. After several years of this various attempts I realized that the difficulty was both epistemological and linguistic. (…) I had to stop looking at living systems as open systems defined in an environment, and I needed a language that would permit me to describe an autonomous system in a manner that retained autonomy as a feature of the system or entity specified by the description. In other words, any attempt to characterize living systems with notions of purpose or function was doomed to fail because this notions are instrinsically referential and cannot be operationally used to characterize any system as an autonomous entity. Therefore, notions of purpose, goal, use or function, had to be rejected, but initially I did not know how. (…)
When Jerry Y. Lettvin and I wrote our several articles on frog vision (…), we did it with the implicit assumption that we were handling a clearly defined cognitive situation: there was an objective (absolute) reality, external to the animal, and independent of it (not determined by it), which it would perceive (cognize), and the animal could use the information obtained in its perception to compute a behaviour adequate to the perceived situation. This assumption of ours appeared clearly in our language. We described the various kinds of retinal ganglion cells as feature detectors, and we spoke as detection of prey and enemy. We knew that was not the whole neurophysiological story, as was apparent particularly in the discussion of the article called “Anatomy and Physiology of Vision in the Frog (Rana pipiens)“. But even there the epistemology that guided our thinking and writing was that of an objective reality independent of the observer. Thus, when Samy Frenk and I began to work with pidgeons in 1961, first studying from vision, we aproached that study in the same fundamental view. (…) Yet, when Gabriela Uribe joined us and we in fact began to study color vision in 1964, it soon became apparent to us that that approach leads to deep trouble. Neurophysiologically we did not see anything fundamentally different from what other scholars had already seen. We found the classic types of ganglion cells with sepparate, concentric or overlapping opponent spectral preferences. But we also found: (a) that although the geometry of the receptive fields of the ganglion cells with opponent spectral preferences had nothing to do with the geometry of the visual object, the geometry of the visual objects had to do with the response of those cells; and (b) that we could not account for the manifold chromatic experiences of the observer by mapping the visible colorful world upon the activity of the nervous system, because the nervous system seemed to use geometric relations to specify color distinctions. A different approach and a different epistemology was necessary.
(…) After we realized that the mapping of the external world was an inadequate approach, we found that the very formulation of the question gave us the clue. What if, instead of attempting to correlate the activity in the retina with the physical stimuli external to the organism, we did otherwise, and tried to correlate the activity in the retina with the color experience of the subject?
(…) We did this rigorously, and showed that such and approach did indeed permit us to generate the whole color space of the observer. (…) But what was still more fundamental was the discovery that one had to close off the nervous system to account for its operation, and that perception should not be viewed as a grasping of an external reality, but rather as a specification of one, because no distinction was possible between perception and hallucination in the operation of the nervous system as a closed network.(…)
De la introducción de Autopoiesis and cognition, The realization of the living, de Humberto Maturana y Francisco Varela.