“Even if we cannot see any difference between an original painting and a forgery or between an edible mushroom and a poisonous one, that difference matters in the bearing it has on our behaviour.” --Nelson Goodman
The Oxford English Dictionary defines the noun authenticity as “the quality of being authentic, or entitled to acceptance, 1. as being authoritative…2. as being in accordance with fact…3. as being genuine…4. as being real.”  Authenticity, in these senses, often cannot be deciphered by the human eye alone. Often additional information is required or questions must be asked and answered to determine authenticity. Questions of authenticity, and the degree to which they can be answered, vary from medium to medium. Whether these questions result in a decisive absence or presence or an uncertainty, the authenticity of a painting, a work of literature, a body, an experience, or a discourse all affect the way humans react to it, as Goodman states. Authenticity affects value, meaning and interpretation, acceptance, and human reaction to objects. Questions of authenticity relate not only to aesthetics, but also to philosophy and politics.
The photograph initiates the problem of authenticity. Walter Benjamin writes “The Work of Art in the Age of Mechanical Reproduction” in 1935; he has witnessed a revolution of mechanical production in his lifetime. He examines the role of photography and other forms of mechanical reproduction of art objects. For Benjamin, reproductions of paintings are inauthentic, and the existence of inauthenticity creates the problem of authenticity. He writes, “the presence of the original is the prerequisite to the concept of authenticity” and “…the whole sphere of authenticity is outside technical …reproducibility.”  For Benjamin, authenticity cannot be reproduced, and “even the most perfect reproduction of a work of art is lacking in one element: its presence in time and space, its unique existence at the place where it happens to be.”  For Benjamin, authority is at stake with the emergence of photography: “confronted with its manual reproduction, which was usually branded as a forgery, the original preserved all its authority; not so vis á vis technical reproduction.”  Benjamin provides two reasons for this possibility: photographs might capture something “unattainable to the naked eye,”  and reproducibility “can put the copy of the original into situations which would be out of reach for the original itself…,”  resulting in the depreciation of the quality of an original’s presence.
André Malraux describes the photograph in particular as opening “a museum without walls” that “will carry infinitely father that limited revelation of the world of art which the real museums offer us within their walls...”  Malraux here sees the expansive possibilities for the accessibility of art. Malraux argues that photography “often substitutes the significant work for the obvious masterpiece,”  causing not only the viewer but the artist to “revis[e] their attitude toward the very concept of a masterpiece.”  Malraux notes photography can change conception of the relative size of juxtaposed objects and alter the impression a sculpture gives based on the size, lighting, or focus of a photograph. Photography, for Malraux, changes and rearranges how works of art are seen in history.
Questions of the authenticity of paintings themselves often revolve around “when, where and by whom a picture was painted.”  In this manner of thinking, “the question ‘is it authentic?’ must be replaced by… ‘is it an (or the) authentic so-and-so?’”  Here, Goodman means that much discussion of the authenticity of a painting relates to trying to decipher if a painting of unknown origin is, for example, an authentic Picasso or the authentic “Las Meninas”.
Questions of the authenticity of an art object are not limited to discussions related to reproduction or possible forgery. They also include: What kind of painting is authentic? And what kind of painting is to be accepted or authoritative? Pablo Picasso’s “Les Demoiselles d’ Avignon” (1907) features five prostitutes with angular bodies that represent the beginning stages of the geometric figures that define cubism. The bodies face various directions and the work “overturns the perspectival system that had ruled pictoral space since the Renaissance.”  Among others, the work raises questions about traditional perspective and representation of the body. Can representation that is less mimetic of reality than traditional forms be more authentic than traditional forms? Should breaking traditional norms be highly valued? What is considered beautiful? These are questions that faced modernist paintings such as this one.
What kind of painting is authoritative relates to high art vs. low art debate, which is often looked at in terms of avant-garde vs. kitsch. For Clement Greenberg “Kitsch is vicarious experience and faked sensations,”  which “now and then…produces…something that has an authentic folk flavor” but “these accidental and isolated instances have fooled people who should know better.”  Greenberg praises work that does something new for painting, that presents a new phase in historical trajectory, and he criticizes kitsch because he feels it does nothing new for painting.  While those who praise surrealist paintings such as Dalí’s “Persistencia de la Memoria” (1931) laud the collage effect16 of real images such as clocks presented in unrealistic shapes and juxtapositions, critics such as Greenberg find Dalí’s work merely competent. For Greenberg, Dalí does something new for images (presenting images out of proportion, in ways not imitative of reality), but he does nothing new for painting, which is Greenberg’s preference. Greenberg praises works such as Jackson Pollock’s “Autumn Rhythm” (1950) for shattering artificial perspective and toying with the space of painting. 
The authenticity of a work of literature is questioned and debated somewhat differently. Questions about authenticity, in the sense of accordance with fact, surround nonfiction writing (as well as documentary film and photography). Many of these questions began with New Journalism, which emerged in the United States in the late 1950s and the 1960s. It involves adding novelistic elements such as character description, character sketches, and dialogue to reporting. Its emergence provoked questions for and criticisms of writers such as “the bastards are making it up!”  With New Journalism arrived the “nonfiction novel,” which Truman Capote claimed to invent with his work In Cold Blood (1965), though others have debated this. A proliferation of terminology such as “memoir,” “creative nonfiction,” “new journalism,” “nonfiction novel” surround writing based in reality and on real people but filtered through the opinions and interpretations of the author. The factual nature or authenticity of this kind of writing often results in public debate that cannot be settled. In present day this type of debate is more common in the realm of nonfiction writing on controversial political topics verses the overall criticism of the style, which current readers are more familiar with than readers were in the 1950s and 1960s.
Similar to the questions that nonfiction writing raises about representation vs. real event, or degrees of mimesis, questions about the authenticity of a body are raised in films such as Spike Lee’s Bamboozled, wherein the concept of “racial authenticity” comes into view in relation to both the representation of black people in the “Mantan” television show and the character of Peerless/ Pierre. “Mantan” features characters in “blackface” which Pierre thinks “will lend authenticity.” Within the film itself this representation is quite controversial and results in protest, death, and destruction provoked by those who do not feel the representation is at all authentic or just. Not only are characters within the film deciding on the authenticity or genuineness of representation, but also the viewers of the film are provided with “real” people to compare to television representation within the film and in reality. Further, the idea of being “really black” is brought to light with the character Peerless/ Pierre and those who interact with him within the film and as viewers. Other characters in the film rarely call Pierre by his name. Instead he is “Peerless” or “Dela,” implying he is perhaps not what he thinks he is or seems to be. As “Peerless” he is alone, perhaps distanced from his racial group, perhaps not a part of his peers or some other group, or perhaps some combination of these. Questions of the authenticity of a body are inherently confusing; how can one not be of or like their body? The question of “really black,” therefore, inserts a notion of black as a way of being.
Do our experiences have authenticity, are they real? In Plato’s Republic, Plato sees most of human experience as inauthentic because he views media as a negative filter clouding experience. The media is like the cave in his “Allegory of the Cave.” He believes some experiences can be unmediated and therefore real, and one arrives at them through philosophy. Aristotle, in Poetics, views media as a positive method for learning and imitation as natural to mankind or in other words part of authentic life. Similarly, how do we know if we live with authenticity? This is a question that Martin Heidegger examines in Being and Time. For Heidegger, “inauthentic” is something like being that is not fully owned or one’s own. Dasein is inauthentic in its exposure to the world. When witnessing and measuring itself and its being against others, dasein sees that it is in them, and dasein cannot maintain that its self is solely its own; but dasein has not lost itself but found itself in the wake of pieces of the world that it sees are itself. This is “tranquillizing”  for dasein, and therefore, for Heidegger, inauthenticity is not bad or cheap or fake, but rather sharing qualities with others. 
Adorno, in The Jargon of Authenticity criticizes various scholars, including Heidegger, for what he calls the existentialists’ “jargon of authenticity.”  He criticizes existentialism, as Schroyer puts it, because it “mystified the actual relation between language and its objective content.”  Adorno writes, “While the jargon overflows with the pretense of deep human emotion, it is just as standardized as the world that it officially negates; the reason for this lies partly in its mass success, partly in the fact that it posits its message automatically, through its mere nature.”  We might say, then, that Adorno criticizes the “jargon of authenticity” for what he sees as its inauthenticity.
While authenticity is often what is looked for or most highly valued as a commodity, we must not forget that humans often prefer the inauthentic, ranging from preferring fantasy to reality or a print to an original based on cost. Questions of authenticity are often up to the beholder to decide or invisible to the eye. Nonetheless we often desire to know what is authentic, and when we know or decide it changes how we act.