Throughout time, the ways in which images relate to the world and the types of relations they establish with it have paved the way to several image theories, i.e., different knowledge and beliefs that have contributed to our understanding of images and the cultural planes that have welcomed them. These theories were based on debates over the nature of image, its conditions of use and its cultural value from an early stage. Despite their ancestral origin, they fix expectations that are addressed to images to this day, namely as far its contribution to Truth, Good and Education are concerned.
Greek thought began by describing the functioning of image through the concept of imitation (mimesis), i.e., as a productive act that operates through relations of similitude with an ideal world or with the natural world. It was precisely this distinction between similitude or imitation (of real objects or of ideas) types that were at the origin of the first image valorisation and hierarchisation criteria. In Book X of Republic, Plato recognised good images are all those that dedicate themselves to imitating ideas rather than the natural (or sensitive) world. We may then understand why one of the early planes upon which image was thought was that of Metaphysics. From an early stage, Greek thought described the functioning of image as the visible side of an invisible reality, the doubling and visible manifestation of an Idea. The word eikon came up precisely to designate image in its relation with ideas, forms, archetypes, i.e., with a supra-sensitive world whose essence belongs to the invisible. Images make this (ideal) world «contemplable», «visible», as they participate in its substance (they are consubstantial to them).
The Jewish-Christian tradition extended and intensified this metaphysical economy of image due to its need to keep the sacred within the invisible: its iconic culture had the privilege of making the faces and refulgences of the sacred visible with no intervention from the human hand (acheropoietos). However, these traditions also soon feared this metaphysical setting might not hold all images, as well as their mimetic compulsion. This ultimately meant the acknowledgement of a certain power of images, namely their power to avoid a relationship with ideas and to institute themselves through relationships with things, setting unmodelled presences in the «world of pure immutable essences» (Plato) or, later, in the figural world recognised and authorised by the dogmas of the church. Simulacrum (eidolon), the image that creates the illusion that it may create reality itself, which Plato claims was enough for the sophists, poets and painters, has its equivalent in Jewish-Christian tradition in the concept of «idol» (the representation of a divinity, which was able to be culted, as it became mixed with it). This unwillingness towards these images was further repeated in the religious plane: there were appeals not to make idols, i.e., other gods or «false transcendences», at the same time as a theology of image started to recognise the need to intervene in the ontological recharacterisation of image, namely regarding expectations on the contiguity of sacred images.
In the Byzantine Empire of the 7th and 8th centuries, a plethora of edicts and decrees opposed the more traditional, iconoclast stance of the church (who believed deeply in the consubstantiality between image and what it represented, arguing the material and physical dimension of image would, in the specific case of sacred images, corrupt the dimension of the invisible) to the more moderate, iconophile position (which holds that venerating icons of Christ, the Virgin, angels and saints is not idolatry, as the homage to the icon reaches the «prototype»). Faced with strong political and military pressure at the borders of the Empire (namely by an 'uniconic' Islam), the decisive argument of iconophile patriarchs focused on the dogma of Incarnation, hinting that, as God chose to incarnate human form through the figure of Christ, making him in His image, also man, by imitating Him, might produce images that would lead him to God. It was precisely upon this economy, i.e., the understanding of the double dimension of Christ (divine and human, word and flesh, visible and invisible), that the priests’ thinking on image was built. The economy concept was basically a move away from the consubstantiality thesis: conversely, it assumed a chance to access the manifestation of the divine through image (translatio ad prototypum). Hence, it was decisive for theology to contain as much as possible image within this sense of the double, the reflection, i.e., to install image as painting or as a mediating instance that generates the possibility of a look or of a reference to a model: «Christ is not in the icon, the icon is oriented towards Christ, who does not cease to recede.» (Marie-José Mondzain, 1996: 117)
This demarcation paved the way to a definition of the terms of an artificial image, i.e., an image that stopped being «almost the same» as that which it designated (which, according to Foucault, was framed within the unitary system of thought due to its similarity with pre-classical episteme) and was progressively seen as a re-presentation, a separation (instead of a sole instance) that establishes connections (instead of a presence). It is as representation (a notion that is essential to a theory of signs) that the modern world refers to image: as something that means something that is not present (and therefore as a sign of something) and proposes itself as a transitive operation (reference) of a first instance, a referent. To the moderns, the combination of the two instances (representation and the referent) is not operated by mere continuity (in which case image would be deemed transparent), but on a symbolic plane, i.e., within a culture (as well as its agreements and conventions) that would enable its mediation. The sign is thus progressively seen as a triad (instead of a dual relation): it cannot dispense concepts, meanings or discourses, as they are an active part in its genesis.
The concerns about image as an instance of meaning had initially been set by an Iconology (duly systematised since the 16th century), i.e., by a discipline that explains images, their symbolic roots, but that mostly set the visual limits of symbologies. The perspective from which all early work on the semiological analysis of image started in the 1960s was precisely the acknowledgment of the conventionality of visual forms and their similitudes (its signic nature), which was decisive to contradict its apparent naturalities. For that purpose, it was based on Ferdinand de Saussure’s modern linguistics, namely his argument on the arbitrary dimension of the sign (in his Course of General Linguistics (1906-10) Saussure recognises sign as a psychic entity with two unseparatable sides: a signifier (or «acoustic image») and a signified (or «concept»), whose relation he held was unmotivated and conventional). It was thus demonstrated that similitude is not a mere act of copying, rather than a selective act that searches for an affinity with the ideas of a particular period and its visual culture (Gombrich, Goodman, Metz). This epochal and cultural adjustment allowed for the understanding that the codes that structure iconic signs are weak, i.e., unstable and subject to frequent mutations (Eco, 1975). We also owe to image semiology the enlightenment of the incursions of image in rhetoric, as well as its textual and ideological «anchorings» (Barthes).
However, this period also saw the consolidation of technical images: image theories accordingly dedicated themselves to the specification of their distinctive feature, as they soon understood its nature did not depend on an imitation in the conventional sense, rather than an automatism-fitted register which depended on the presence of the represented objects or, as Roland Barthes specified in his book Camera Lucida, a double liaison between the real and the past (which can be summed up by the phrase «this was»). The North-American logician Charles Sanders Peirce had already sensed this specificity, as he allowed for photography to be framed within his second class of signs: signs by direct physical connection – indexes that become marks or traces of the objects from which they stem. Due to its contiguity relation with what it represents, photography has the power to prove its existence, indicating the object from which it was projected. This indicial nature of photography gave rise to an ontological basis (Bazin, Barthes and later Sontag, Krauss, Dubois, among others) that allowed for the wide dissemination of these images (valued for their power of register, confirmation and even objectivity), and contributed to the consecration of some of the main modern institutions, from science to justice. One of the most recognised effects of this profound valorisation of technical images was its enormous modern expansion, as well as its growing attractiveness for diverse areas of experience (Vilém Flusser recognises they have become «dams», in the sense that everything tends to gather towards them) – here probably lies a new idolatry. As a result, in this image-riddled world, things become consistent not because they exist but because they are represented and may become images. If, on the one hand, these reasons turned all of us into permanent spectators (as Debord sensed it) of a world that is cross-dressed into images (or appearances), on the other hand, it progressively generates the disquieting idea that many, which are now virtual and computationally-processed, do not hold in a real world, but in the imagination, concepts and ideas once know as «invisible».
This is largely the reason for the frequent appeals to an understanding of the languages, codes and programmes that format those images that can be felt today, warning us of the fact that they are second-order abstractions, i.e., the application of sophisticated texts, formulas (Flusser), and that they are possibly based on metaphysics. The recognition of their nature may be able to restrain some «magical» and ancestral attitudes that are still a feature of many of its interpretations, which insist on not seeing it as a sign, as an agent of a message, rather than as Image, as an instance that «puts it in the presence» of its motive.