According to Michel Foucault, the great project of this thought is an exhaustive ordering of the world characterized by "discovery of simple elements and their progressive combination; and at their center they form a table on which knowledge is displayed contemporary with itself. The center of knowledge in the seventeenth and eighteenth centuries is the table. ''(68). Ernst Cassirer's reading of the Enlightenment, though unfashionable now, more than echoes certain parts of Foucault's construction of "classical thought." While much Anglo-American intellectual history tends to pose an atomization of cognition in this period, Cassirer sees a Leibnizian underpinning to eighteenth-century thought:
Cassirer might well have agreed with Foucault that observation in the seventeenth and eighteenth centuries is "a perceptible knowledge." 70) But it is hardly a knowledge that is organized exclusively around visuality. Although the dominance of the camera obscura paradigm does in fact imply a privilege given to vision, it is a vision that is a prlori in the service of a nonsensory faculty of understanding that alone gives a true conception of the world. It would be completely misleading to pose the camera obscura as an early stage in an ongoing autonomization and specialization of vision that continues into the nineteenth and twentieth centuries. Vision can be privileged at different his- torical moments in ways that simply are not continuous with one another. Sit- uating subjectivity within a monolithic Western tradition of scopic or specular power effaces and subsumes the singular and incommensurable procedures and regimes through which an observer has been constituted.(71) For example, Berkeley's theory of perception is based on the essential dissimilarity of the senses of vision and touch, but this insistence on the heterogeneity of the senses is remote from nineteenth-century notions of the autonomy of vision and the separation of the senses.(72) Berkeley is hardly alone in the eighteenth century in his concern with achieving a fundamental harmonization of the senses, in which a key model for visual perception is the sense of touch. The Molyneux problem, which so preoccupied the thought of the eighteenth century, poses the case of a perceiver who is ignorant of one of the languages of the senses, namely sight. The best known formulation of the problem is Locke's:
But regardless of how the problem was ultimately answered, whether the claim was nativist or empiricist, the testimony of the senses constituted for the eighteenth century a common surface of order.(74) The problem quite simply was how the passage from one order of sense perception to another took place.(75) Or for Condillac, in his famed discussion of the senses coming to life one by one in his statue, the problem was how the senses could "reconvene," that is, come together in the perceiver.(76) But for those whose answers to Molyneux were, in one way or another, negative - a blind man suddenly restored with sight would not immediately recognize the objects before him - and these included Locke, Berkeley, Diderot, Condillac, and others, they share little with the physiologists and psychologists of the nineteenth century who were also, with greater scientific authority, to answer the question negatively. By insisting that knowledge, and specifically knowledge of space and depth, is built up out of an orderly accumulation and cross-referencing of perceptions on a plane independent of the viewer, eighteenth-century thought could know nothing of the ideas of pure visibility to arise in the nineteenth century. Nothing could be more removed from Berkeley's theory of how distance is perceived than the science of the stereoscope. This quintessentially nineteenth-century device, with which tangibility (or relief) is constructed solely through an organization of optical cues (and the amalgamation of the observer into a component of the apparatus), eradicates the very field on which eighteenth-century knowledge arranged itself.
From Descartes to Berkeley to Diderot, vision is conceived in terms of analogies to the senses of touch.(77) Diderot's work will be misunderstood if we do not see at the outset how deeply ambivalent he was toward vision, and how he resisted treating any phenomenon in terms of a single sense,.78) His Letters on the Blind (1749), in its account of Nicholas Saunderson, a blind mathematician, asserts the possibility of a tactile geometry, and that touch as well as sight carries with it the capacity for apprehending universally valid truths. The essay is not so much a depreciation of the sense of vision as it is a refutation of its exclusivity. Diderot details Saunderson's devices for calculation and demonstration, rectangular wooden boards with built-in grids marked out by raised pins. By connecting the pins with silk threads Saunderson's fingers could trace out and read an infinity of figures and their relations, all calculable by their location on the demarcated grid. Here the Cartesian table appears in another form, but its underlying status is the same. The certainty of knowledge did not depend solely on the eye but on a more general relation of a unified human sensorium to a delimited space of order on which positions could be known and compared. (79) In a sighted person the senses are dissimilar, but through what Diderot calls "reciprocal assistance" they provide knowledge about the world. Yet despite this discourse on the senses and sensation, we are still within the same epistemological field occupied by the camera obscura and its overriding of the immediate subjective evidence of the body. Even in Diderot, a so-called materialist, the senses are conceived more as adjuncts of a rational mind and less as physiological organs. Each sense operates according to an immutable semantic logic that transcends its mere physical mode of functioning. Thus the significance of the image discussed in Diderot's letters on the Blind: a blindfolded man in an outdoor space steps forward, tentatively olding a stick in each hand, extended to feel the objects and area before him. But paradoxically this is not an image of a man literally blind; rather it is an abstract diagram of a fully sighted observer, in which vision operates like the sense of touch, just as the eyes are not finally what see, however, so the carnal organs of touch are also disengaged from contact with an exterior world. Of this blind and prosthesis-equipped figure that illustrated Descartes's La dioptrique Diderot remarks, "Neither Descartes nor those who have followed him have been able to give a dearer conception of vision."(80) This anti-optical notion of sight pervaded the work of other thinkers during both the seventeenth and eighteenth centuries: for Berkeley there is no such thing as visual perception of depth, and Condillac's statue effectively masters space with the help of movement and touch. The notion of vision as touch is adequate to a field of knowledge whose contents are organized as stable positions within an extensive terrain. But in the nineteenth century such a notion became incompatible with a field organized around exchange and flux, in which a knowledge hound up in touch would have been irreconcilable with the centrality of mobile signs and commodities whose identity is exclusively optical. The stereoscope, as I will show, became a crucial indication of the remapping and subsumption of the tactile within the optical.
66. Martin Heidegger, "The Age of the World Picture," in The Question Concernlng Technology and Other Essays, trans. William Lovin (New York, 1977), pp. 115-54.
67. Descartes, "Rules for lhe Direction of the Mind," in Philosophical WrItings, pp. 19, 21
68. MichelI Foucault, The Order of Things (New York, 1970), pp. 74-75. On Leibniz and the table, see Gilles Deleuze, Le pli, p. 38.
69. Ernst Cassirer, The Phllosophy of the Enllghtenment, trans. Fritz Koehn and James P. Pettegrove (Princeton, 1951), p. 23. An alternative continental reading of this aspect of eighteenth-century thought is Max Horkheimer and Theodor Adorno, Dialectic of Enlightenment, trans. John Cumming (New York, 1979). For them, the quantitative "unity" of Enlightenment thought was continuous with and a precondition for the technocratic domination of the twentieth century. "In advance, the Enlightenment recognized as being and occurrence only what can be apprehended in unity : its ideal is the system front which all and everything follows. Its rationalist and empiricist versions do not part company on that point. Even though the individual schools may interpret the axioms differently, the structure of scientific unity has always been the same… The multiplicity of forms is reduced to position and arrangement, history to fact, things to maner" (p. 7).7
70. Foucault, The Order of Things, p. 132. On the problem of perception in Condillac and Diderot, see Suzanne Gearhart, Open Boundary of Fiction and History: A Critical Approach to the French Enlightenment (Princeton, 1984), pp. 161-199.
71 See Martin Jay, "Scopic Regimes of Modernity," in Vision and Vlisuality, ed. Hal Foster (Seattle, 1988), pp. 3-27.
72 Anglo-American criticism often tends to posit a continuous development of eighteenth-century thought into nineteenth-century empiricism and associationism. A typical account is Maurice Mandelbaum, History. Man and Reason: A Study In Nineteenth Century Thought (Baltimore, 1971, especially pp. 147-162. After insisling on a continuity between the thought of Locke, Condillac, and Hartley and nineteenth-century associationism, Mandelhaum concedes, "Thus, in its origins, associationism was not what James Mill and Alex- ander Bain later sought to make of it, a full-blown psychological system, serving to classify and relale all aspects of mental life; it was, rather, a principle used to connect a general epislemological position with more specific issues of intellectual and practical concern. Among these issues, questions concerning the foundations of morality and the relations of morality to religion had an especially important place" (p. 156). However, what Mandelbaum terms "a general epislemological position" is preciselyt he relative unity of Enlightenment knowledge onto which he imposes the separations and categories of the thought of his own lime. Religion, morality and epislemology did not exist as discrete and separate domains.
73. John Locke, An Essay Concerning Human Understanng, II, ix, 8.
74. For example, see Thomas Reid, Essays on the Powers of the Human Mind [178S] (Edinburgh, 1819), vol. 2, pp. 115-116: "If any thing more were necessary to be said on a point so evident, we might observe, that if the faculty of seeing were in the eye, that of hearing in the ear, and so of the other senses, the necessary consequence of this would be, that the thinking principle, which I call myself, is not one but many. But this is contrary to the irresistable conviction of every man. When I say, I see, I hear, I fed, I remember, this implies that it is one and the same self that performs all these operalions."
75. See Cassirer, The Phillosophy of the Enlightenment, p. 101. For recent discussions of the problem, see M. J. Morgan, Molyneux's Question: Vision, Touch and the Philosophy of Perception (Cambridge, 1977); and Francine Markovits, "Mérian, Diderot et l'aveugle," in J.-B. Mérian, Sur le problème de Molyneux (Paris, 1984), pp. 193-282.
76. Etienne de Condillac, ''Trailé des sensations" (1754), in Oeuvres philosophiques de Condillac, vol. I, ed Georges Le Roy (Paris, 1947-1951).
77. See Michel Serres, Hermès ou la communication (Paris, 1968), pp. 124-125; and Maurice Merleau-Ponty, The Primacy of Perception, ed. James M. Edie (Evanston, Ill., 1964), pp. 169-172.
78. On Dlderot's attitude toward the senses, see Ellsabeth de Fontenay, Diderot. Reason and Resonance, transl. Jeffrey Mehlman (New York, 1982), pp. 157-169.
79. On the persistence of Cartesianism in Enlightenment thought, see Aram Vartanian, Diderot and Descates: A Study of Scientific Naturalism In the Enlightenment (Princeton: 1953)
80. Diderot asserts that the person most capable of theorizing on vision and the senses would be "a philosopher who had profoundly meditated on the subject in the dark, or to adopt the language of the poets, one who had put out his eyes in order to be better acquainted with vision." Lettres sur les aveugles, in Oeuvres philosophiques, p. 87.
Jonathan Crary, Techniques of the Observer: On Vision and Modernity in the Nineteenth Century, Cambridge (Mass.)-London, MIT Press, 1990, pp. 57-62
A página Origins of Modern Visual Culture, de Jonathan Crary, no site da Columbia University, tem vários recursos interessantes, sendo, porém, raros os universalmente acessíveis (isto é, sem "password"). Language as Vision: The Ocularcentrism of Chomskyan Linguistics, de Chris Werry, centra a questão estudada por Crary no texto acima reproduzido no território da linguística. Poderá ser útil a consulta das notas de leitura da obra citada de Crary, por Ron Broglio e por Garnet Hertz.