Since antiquity, philosophers have been theorizing about art, as well as criticizing it. Plato, for example, regarded art as an inferior form of knowledge, indeed, no more than an illusion of knowledge. In the Republic he describes the painter as a “creator of appearances,” stating that “what he creates is untrue,” a “semblance of existence” rather than a “real existence.” A painting is at best “an indistinct expression of truth.” Plato distinguishes between the image of something, or the thing itself, and the true idea of the thing, which exists in the mind of God, as it were. According to this understanding, the painter deals with the image rather than the thing, let alone the idea of the thing. Thus, art is deception: “A painter will paint a cobbler, carpenter…though he knows nothing of their arts; and, if he is a good artist, he may deceive children or simple persons, when he shows them his picture of a carpenter from a distance, and they will fancy that they are looking at a real carpenter.” Plato writes that works of art are “but imitations thrice removed from the truth, and could easily be made without any knowledge of the truth, because they are appearances only and not realities.” Imitation—image-making—should not be “the ruling principle of [anyone’s] life, as if he had nothing higher in him.” One might call this metaphysical criticism: art is at best a way of simplifying and communicating complex ideas—philosophical truths—to the ignorant, according to Plato, although from the point of view of absolute truth, the artist is also profoundly ignorant.

Aristotle took a somewhat different approach to his theory of art, although he also regarded art as a form of imitation. In his Poetics, perhaps the most influential work on art ever written, he makes it clear that art is a moral issue, since it deals with human character. “The objects of imitation…represent men either as better than in real life, or as worse, or as they are.” He argues that imitation is a human instinct, and as such, works of imitative art, in whatever medium, move human beings deeply. Such works of art are evocative and cathartic; the viewer identifies and empathizes with the human beings and human situations depicted, feeling what they felt, and learning from their experience, which is an essentialized imitation of what all might experience. Thus, the viewer pities those who suffer in tragedy—the highest form of art, since the tragic hero is a higher type of human being—while being terrorized by their suffering and the situations which cause it, for they are potentially the viewer’s own, in spirit if not in actuality. For Aristotle, art is a lesson in life and, as such, is of great social and broadly human value. He was the first psychologically minded critic, and his idea of the inseparability of art and morality—of art in the service of moral teaching—remained influential into the modern period.

The ancient philosopher Plotinus saw art as more mystical than mundane. He was the founder of Roman Neoplatonism, and his thinking about art reflects that of Plato, with important, influential differences: Plotinus introduced the idea that art can be beautiful and that its worldly beauty is a reflection of a higher, spiritual beauty. According to Plotinus’s Enneads, by intellectually contemplating beautiful art, we can gain insight into and even commune—mystically merge—with that higher beauty. Plotinus connects art directly with the higher realm of ideas from which Plato excluded it and characterizes that realm as spiritual as well as intellectual—that is, he emphasizes the spiritual aspiration involved in intellectual analysis and intuition. It is a view that was present, though latent, in Plato. For Plotinus, art was an enigmatic embodiment of pure spirit, which is why artistic beauty has something sacred and abstract about it.

In a sense, all subsequent art criticism is an elaboration of these three philosophers’ ideas, sometimes in combination: art can be seen as imitation, as psychological and moral, and as spiritual. Yet, while these thinkers established important, lasting ideas about the philosophy of art, they were not true art critics. Art criticism is necessarily less general than philosophical theorizing about art, however informed by theoretical generalizations it may be. In his seminal book History of Art Criticism (1936), Lionello Venturi asks: “What is criticism if not a relationship between a principle of judgment and the intuition of a work of art or of an artistic personality?” The principle of judgment can be informed by general ideas about art, but the intuition of a work of art or an artistic personality necessarily involves getting down to particulars. Thus, for Venturi, the Greek Xenocrates of Sicyon (3rd century bce) was the first art critic, for he “tried to fix a relationship between his own artistic principles, as categories of artistic judgment, and some concrete artistic personalities.” In other words, Xenocrates—a sculptor of the school of Lysippus—had a philosophy of art, which he brought to bear on the work of particular artists, evaluating them and finding the truth in their art by its measure.

Xenocrates’ approach continued into Roman times. The writers Lucian and Kallistratos declared: “A work of art requires an intelligent spectator who must go beyond the pleasure of the eyes to express a judgment and to argue the reasons for what he sees.” Again: “A connoisseur is one of those men who, with a delicate artistic sense, know how to discover in works of art the various qualities they contain, and mix reasoning with such an appreciation.” Thus, the ancient viewpoint regards the critic as a connoisseur—a person who knows and values art, which requires reason as well as sensibility. Indeed, according to the philosopher Quintilian, the true connoisseur—the really expert judge of art—is able, in Venturi’s words, to “understand the reason of art, while the unlearned feel only the voluptuousness.”

Theorizing about art continued during the Middle Ages under a Christian banner. Although there was a certain awareness of the material character of contemporary art, philosophers made no serious effort to synthesize the material with the theoretical, nor did they illustrate their theories by discussing particular artists. In general, thinkers from the Middle Ages were concerned with art’s symbolic meaning, evident in moral and religious iconography. Also, like Plato, they distinguished between the judgment of the senses and the judgment of reason, the latter being superior because it is based on laws of beauty given by God. St. Augustine used his Christian faith as a theoretical tool. In De natura boni, among other writings, he elaborates the ideas of Plotinus, emphasizing the transcendence or sublimity of absolute beauty, of which the beauty of the work of art is a reflection (albeit a pale one). He discusses the formal character of pictures, often in terms that indicate his religious concerns: thus, black is ugly, but if used the right way it is beautiful, just as the universe is beautiful, even though it contains sinners, who are ugly. In Summa theologiae (c. 1265/66–73), St. Thomas Aquinas, also using Christianity as his theoretical model, distinguishes between the higher senses—sight and hearing—which are a means to organized knowledge, and the lower senses—touch, smell, and taste—which are not. But St. Thomas moves beyond the usual tenets of Christian theory when he suggests that beauty is admirable because it stimulates theoretical thinking and pleasurable because it satisfies desire—a very modern idea.