Transparency in Postwar France
A Critical History of the Present
Stefanos Geroulanos



Was Transparency an Optical Problem?

A Short History

Thanks to common usage and etymology, transparency is usually taken to be mainly a visual matter. The noun transparentia did not exist in classical Latin; it is a medieval creation, formed in calque of the ancient Greek διαφάνεια—a derivative of compounds like the verb διαφαίνω (“show through,” “allow the light to pass”) and the adjective διαφανής (“translucent,” but also “manifest,” “conspicuous,” and even “red-hot”): trans- rendered δια-, while the main part of the word was formed on the Latin counterpart of the Greek φαίνω (“bring to light, cause to appear,” etc.): pareo, parere (“appear/be visible”). The Oxford English Dictionary concentrates on two definitions: “(1a) The quality or condition of being transparent; perviousness to light; diaphaneity, pellucidity,” and “(2a) That which is transparent; a transparent object or medium.”

Yet we should recall that the optical meaning has never been predominant or self-sufficient. As early as Plato, the notion of transparency was used in inquiring about the purity of the soul; in late antiquity, by Saint Augustine’s time, it had become replete with religious connotations. Transparency is more than visual transparency.

The visual field has been a privileged site for the concept of transparency, but the latter is neither restricted to nor metaphorically derivative of it. Furthermore, transparency poses conceptual rather than simply visual problems. What we mean by “transparency” affects (and is affected by) the way sensation, objects, and materiality—not to mention mediation, objectivity, light—are constructed within a system of thought: were we to press the point, we would have to admit that transparency is a concept that has made sensation, perception, mediation, and knowledge possible. “Manifestation” and “showing through” are conceptual, epistemological, and not simply visual issues. The dragonfly that struggles against a glass ceiling, like the bird that flies into a window, suffers from a surfeit of the visual and lacks a concept of transparency, a way of managing what shines through, and through what it shines. Still, this dependency on the visual requires a demonstration: a few words on the history of visual transparency and its enmeshing with epistemology, phenomenology, and ethical prerogatives are in order. I focus on four reference points—Aristotle, Descartes, Newton, and the French Enlightenment—from the specific perspective of postwar France.

The inaugural text for Western theories of transparency as a visual concept is Aristotle’s De anima (On the Soul), which treats transparency as a positive quality of objects—a quality that some have to a greater degree than others.1 It is an actuality that, thanks to the texture and consistency of an object, facilitates the absorption and retransmission of color. Its positivity resides in the property of a body to be revealed thanks to the color of other bodies. The diaphanous is here in conceptual interplay with color, light, and the nature of the thing itself. Aristotle argues:

There is, surely, something transparent. And I call transparent what is visible, not strictly speaking visible in itself, but because of the colour of something else. Of this sort are air, water, and many solid bodies; for it is not qua water or qua air that these are transparent, but because there exists in them a certain nature which is the same in them both and also in the eternal body above. Light is the activity of this, the transparent qua transparent.2

At issue here is the structure of perception; perception links transparency to light and to the experience of the world in a way that would remain definitive for subsequent treatments of the problem all throughout the Roman period, and again in the high and later Middle Ages, around Thomas Aquinas.3 Indeed light appears thanks only to the transparent.4 Only through this medium does it allow one to see and to see through. Light is, perhaps astonishingly for us, premised on the transparent and impossible without it: it is transparency become “active.”

The later tradition of treatises on optics is replete with considerations of transparency that bind it to these conceptual operators: light, color, thinghood.5 In Aristotle’s definition, “space” is latent in “light,” given the scaffolding provided by air (which, again, is not transparent as air, but is air because it is transparent), but by the early modern era, space would become independently meaningful.

Postwar thinkers, following a long tradition, credited Descartes with joining optical transparency to ethics and clarity of thought. In his first work, The World, or Treatise on Light, originally published in 1632, Descartes famously called air a “body” that the senses do not perceive unless affected by wind, cold, or heat; its exemplary transparency was a matter of the interaction between light and the senses.6 He also began to use light as a metaphor for the absolute certainty and clarity that mark and guide the philosopher’s thought and ethical life. His lumen naturale, “natural light,” became the decisive figuration of human reason: natural light, “the faculty of knowledge which God gave us . . . cannot encompass any object which is not true, insofar as it is encompassed by this faculty, that is, insofar as it is clearly and distinctly perceived.”7 In 1926, André Lalande’s seminal Vocabulaire technique et critique de la philosophie still defined lumen naturale as a “synonym of reason, a totality of the truths that are immediately and without doubt evident to the mind as soon as it attends to them.”8

Descartes further used clair (“clear”) and obscur (“obscure”) to motivate important movements in his thought. “Clear” or “clear and distinct” accompanied the ideas and knowledge that facilitate the cogito’s (transparent, correct) understanding of the world,9 while “obscure” gestured toward ideas and manners of thought that hampered clear thinking.10 Natural light guaranteed an object’s transparency to the mind through a movement that emanated from God and was experienced and mediated by the mind. Here is the full translated title of Descartes’s incomplete work La recherche de la vérité par la lumière naturelle (The Search for Truth):

The Search for truth by means of the natural light that, all pure and without recourse to religion or philosophy, determines what opinions an honnête homme should hold on any matter that may occupy his thought, and penetrates into the secrets of the most recondite sciences.11

By making the quest for certainty the cornerstone of his thought, by pinning his hopes on universal logic, by pursuing a universal natural language, and by fastening these efforts securely to his own persona as honnête homme, Descartes instituted clarity as the basis of a philosophical perception of the world and of an ethics that would culminate in les lumières—“the lights,” or the Enlightenment. In this tradition, the self-transparency of thought became an extension of the lumen naturale, but also the necessary requirement for any possible meeting between—or knowledge of—the mind and the object of its contemplation.

Descartes’s approach to air as a transparent body was important to a second scientific tradition as a result of the way in which it attached sensation and perception to the environment. Like Descartes,12 Newton refused to believe that air could be a vacuum. To explain how transparent air could transmit light, he posited that the refraction of light required an all-pervasive ether that was present in, and “much subtiler” than, air; indeed this ether was present not just in the air but in “the eye, the nerves, and into the muscles.”13 Newton’s theory of ether became an essential premise in subsequent theories of space and environment precisely because it denied the existence of vacuum. It postulated a minimal environmental presence where there appeared to be an absence and situated organisms and things within their surrounding worlds, even if their interplay depended on, and hence fostered, a seeming transparency.14 From Descartes and Newton onward, space, air, light, and the environment—and the perception, experience, and knowledge of these presences—became entangled with the definition and experience of the transparent.

The transparent is thus a figure of epistemological as much as visual import. Diaphaneity has had a part in every phenomenology: the transparent was a concept and a metaphor for the presence and materiality of the world to the perceiver. It made the world available and promised clarity and comprehensibility. It was made comprehensible only by an author’s way of describing the world. Nor was the visual element of “transparency” separate from, or prior to, social, political, or ethical concerns. Part of a broader apparatus for understanding the world, transparency in the eighteenth century became a purpose of philosophy, for the lumen naturale was not a politically neutral but a strategic, even combative concept, whose exercise aimed at particular kinds of “clarification.”

Epistemological, ethical, and political transparency would become standard fare during the Enlightenment, which wove together the scientific needs of optics with an extensive use of concepts such as clarity, purity, and light. The brief, unsigned article on “transparency” in Diderot and d’Alembert’s Encyclopédie stuck to summarizing Aristotle, Descartes, and eighteenth-century scientists on how the “rectitude of an object’s pores” allowed light to pass through it.15 However, the major article “Lumière” (Light), which d’Alembert wrote himself, engaged precisely the shared syntax of transparency and light, offering a detailed presentation and criticisms of the Aristotelian and Cartesian optical theories of light. Lumière, of course, also made for a major subject of d’Alembert’s “Preliminary Discourse,” which identified natural light and human reason.16

By the 1789 Revolution, the ethicopolitical diction of transparency had drowned the optical one. Jean-François Féraud’s Dictionnaire critique de la langue française (1787–88; Critical Dictionary of the French Language) cited figurative uses, notably a passage from Louis-Antoine Caraccioli about men becoming “transparent” to a perceiver).17 As the historian of science Theresa Levitt has noted (echoing Michel Foucault, Hans Blumenberg, and Jonathan Crary), the rise of optics as a science in nineteenth-century Paris followed the collapse of the apotheosis of light and transparency around the Revolution. Without that phenomenon, modern optics would neither have acquired its own sociopolitical meaning nor developed into the science we know.

In the first years of the nineteenth century, the symbolic power of light took on a specifically modern configuration . . . attendant in the creation of a modern visual culture. Gone was the firm security in light that guaranteed a connection between subject and object. Opacity emerged to take its place alongside illumination. . . . With the dream of complete transparency gone, visibility became a form of discipline. No longer was there the hope that everyone would see everything. Rather, strict control determined who saw what.18

It may come as a surprise that after 1945, scientific optics would play virtually no role in the debate on transparency. After the decline of the utopia of light and reason, the light–vision–space triangle came to be understood much better through the study of the polarization of light in early nineteenth-century Paris, then through Hermann von Helmholtz’s influential studies of the eye, and finally through the discovery of X-rays, which rendered the body transparent and displayed its internal functions undisturbed.19 Yet the twentieth-century sociopolitical tradition saw little reason to register these developments, inasmuch as the metaphor of light remained largely the same as in the eighteenth century. Its invocation continued to follow the same rules—in Georges Canguilhem’s words, “the motor of history is light. Progress is the illumination of shadows.”20 French thinkers in the interwar and postwar periods increasingly viewed the nineteenth century as a Comtean “positive age,” overwhelmed by scientific determinism and by educational projects that advanced “truth” at the expense of metaphysics and outdated beliefs. The persistent image of truth as reliant on the progress of transparency, clarity, and light was annexed to the belief that the human mind had sought to chart the entire world. Auguste Comte, and especially apostles like Émile Littré, had renewed trust in transparency and had marshaled an influential identification of progress with a purified scientific gaze and future social harmony.

Scientific optics was not the only major development bypassed as a result of attitudes to light and transparency. French thinkers by and large neglected the enrollment of perception into psychological theory in the later nineteenth century and the elaborate debates that followed. Particularly striking is the case of Gestalt psychology, which treated light, space, color, and transparency at considerable length.21 In German thought from Johann Gottlieb Fichte and G. W. F. Hegel through Edmund Husserl and Hans-Georg Gadamer, transparency was a matter of consciousness and self-consciousness; these thinkers showed virtually no interest in the visual component.22 And yet, in Germany, Gestalt theory sparked broad interest in psychological perception. Erwin Panofsky used it as the intellectual ground for his 1927 “Perspective as ‘Symbolic Form,’” sharply criticizing the naturalism of visual perspective in the Renaissance as a manifestation of anthropocentrism in the spatial domain.23 In France, by contrast, the polemical and theoretical value of psychological theories was generally discarded (with the exception of Merleau-Ponty).

Martin Jay has argued that vision was subsequently deposed from its position as hegemon over the senses.24 However, it was not a decline, but a renewal of attention to perception around 1930–45—coupled with the recognition that vision classically conceived of could not generate epistemic transparency (something widely accepted across Europe around 1930)—that gave rise to a displacement of vision’s centrality in analysis. Jean Wahl set the stage for a shift in the understanding of perception when he noted: “Perception fails in its explanation of the world . . . we should not make use of perception so as to explain; perception presents, it does not explain.”25 Wahl contended that perception involved, not a direct continuity with the world, but a form of representation to oneself that allowed for a better understanding of the human being’s halting access to the real. Otherwise his claim was not particularly provocative or controversial. Bergson had long dissociated perception from knowledge,26 and a similar idea was seemingly important to Gaston Bachelard, who in his discussion of the notion of philosophical obstacle used a visual metaphor to cast doubt on the epistemological possibility of perfect knowledge: “knowledge of the real is a light that always casts a shadow somewhere.”27 Marcel Mauss deplored the insufficiency of the observer-participant’s localized perception when he called for “a bird’s-eye view” in the form of extensive photo and cinematographic recordings of groups under ethnographic study.28 At that point, Merleau-Ponty, influenced by the phenomenologist Aron Gurwitsch, mobilized Gestalt psychology to challenge the self-sufficiency traditionally accorded to perception.29

A change in the relation between reality and perception had consolidated by the mid-1940s. In 1950, Wahl registered a “new climate” in his account of “The Present Situation and Present Future of French Philosophy”: “French philosophical thought directs itself more and more toward the concrete aspects of imagination and perception, and of the world in general.”30 Attention turned from visual transparency to the counterconcepts of distortion and opacity. In 1955, the medievalist Jurgis Baltrušaitis published a study that bridged philosophy and art history through anamorphoses, distorted representations, as “visionary mechanisms” belonging to the rational as much as to the optic domain. He focused on their capacity to obstruct, displace, and undo forms that emphasized the abstract coherence of reason and perspective: “The anamorphosis bursts into the vertigo of abstraction which balances, to a certain degree, the speculative and semantic reasoning that gravitates around the same forms.”31 From Jacques Lacan’s discussion of anamorphoses (famously in Hans Holbein’s painting The Ambassadors) through Baltrušaitis’s later works, the studies of trompe l’oeil and simulacra undertaken by his fellow medievalist Pierre Charpentrat, and Louis Marin’s study of the “tombs” of absolutism and subjectivity in painting, it appeared that the pretense to transparency in art led directly to a distortion that was not merely visual but symptomatic of broader subjective and phenomenological problems.32

Light, too, could no longer unify experience and claim the power of a lumen naturale that clarified the world: it now pointed to its opposite—darkness and night. In other words, the claim that old theories of perception had been misguided gained credibility alongside the mistrust of vision and the turn to studying the empirical and the concrete, as the emerging “new climate,” new status quo, or “new age” brought new requirements for perceiving and understanding the world. What had appeared as transparent seemed now to paper over the folds and furrows of the empirical.

To attend to optical questions is also to accept firmly that, throughout its history, transparency has served them as a concept and not as a mere fact—as part of a matrix that combined ethics, self-knowledge, epistemology, and politics and was not reducible to vision alone. The sense of transparency reached around 1945 can serve us as an analytical perspective as well. Nothing is simply visually transparent; transparency has no ontological standing. It is the result of a way of looking at the world and identifying objects and media. As a concept, it denotes—at times by way of optical metaphors—a concurrent presence and absence, or presence alternating with absence, which allow something to appear across: something that generally does not interfere unless itself foregrounded, something that is there but absents itself in a way that it makes one aware of its presence, something that is not present in the same way as that which it lets appear. At the end of World War II, these positions gained force from a persistent sense that the war had deformed both reality and perception.


1. Aristotle, De anima 2.7.418b26, trans. D. Hamlyn (Aristotle 1993a).

2. Ibid., 418b3 and 26.

3. On the history of dia- in diaphanous, see Alloa 2011: chs. 2–3.

4. Aristotle, De anima, 419a6 and 28.

5. Vasiliu 1997; Alloa 2011: ch. 2.

6. Descartes, “The World, or Treatise on Light,” in PWD, 1: 85. See also his denial that air is a “mere nothing” in Principles of Philosophy, 1: 71, PWD, 1: 219.

7. Ibid., 30, PWD, 1: 203.

8. VTC, 586, s.v. “Lumière naturelle.”

9. Descartes, Principles of Philosophy, 1: 43–45, PWD, 1: 207.

10. Ibid., 10, PWD, 1: 195–96.

11. Descartes, “The Search for Truth,” PWD, 2: 399–420. As Charles Guignon has put it in referencing the role of Cartesian “natural light” for modern conceptions of knowledge, Cartesian transparency concerns “the attainment of complete clarity through the grounding of our beliefs in the intrinsic intelligibility of the lumen naturale” (Guignon 1993: 136).

12. Descartes, Principles of Philosophy, 2: 17, PWD, 1: 230.

13. Newton 1718: queries 18 and 23, pp. 324, 328.

14. KL, 99.

15. Diderot and D’Alembert 1751–65: s.v. “Transparence,” 16: 558. Citing Newton’s treatment of attraction, the article offered the (somewhat unsatisfactory) counterclaim that it is the unequal density of objects’ parts, or the filling of their pores with “heterogeneous matter,” or yet the absolute emptiness of these pores that allows for their reflection or refraction.

16. Diderot and d’Alembert 1751–65: s.v. “Lumière,” 9: 717–22; also “Discours préliminaire,” ibid., 1: vii–x.

17. Féraud 1787, s.v. “transparence.” I am grateful to Peter Dreyer for this reference.

18. Levitt 2009: 4.

19. On light and utopia, see Baczko 1989.

20. Canguilhem 1987: 441.

21. See, e.g., Fuchs 1923.

22. Gadamer 1976: 205; Gadamer 2013: 216, 232.

23. In France, the use of Gestalt theory to criticize classic theories of perception was carried out only by a few phenomenologists, Aron Gurwitsch and Merleau-Ponty among them.

24. J-DE, ch. 2. Jay has argued that French thought after 1930 is marked by a rethinking of the category of vision, which lost the high status it had enjoyed in the West since the Enlightenment. Despite my enormous respect for Jay’s Downcast Eyes, I describe a webbing of concepts and follow a path quite different from what Jay does when he treats vision as a self-sufficient category and tracks a linear ascent to its “denigration” in twentieth-century France.

25. Wahl 1932: 3.

26. Marrati 2008: 34. On Bergson’s influence around 1930, see Bianco 2015.

27. Bachelard 2002: 24; translation amended.

28. Mauss 2002; work protocols among Mauss’s students already foregrounded these concerns around 1930.

29. On Merleau-Ponty, Gurwitsch, and Gestalt theory, see Geroulanos 2011b.

30. PSF, 49. See also Lacroix 1957: 19.04.4.

31. Baltrušaitis 1984: 8.

32. Charpentrat 1971: 161.