An anachronism (from the Greek ἀνά ana, "against" and χρόνος khronos, "time"), is a chronological inconsistency in some arrangement, especially a juxtaposition of person(s), events, objects, or customs from different periods of time. The most common type of anachronism is an object misplaced in time, but it may be a verbal expression, a technology, a philosophical idea, a musical style, a material/textile, a plant or animal, a custom or anything else associated with a particular period in time so that it is incorrect to place it outside its proper temporal domain.
An anachronism may be either intentional or unintentional. Intentional anachronisms may be introduced into a literary or artistic work to help a contemporary audience engage more readily with a historical period, or for purposes of rhetoric, comedy or shock. Unintentional anachronisms may occur when a writer, artist or performer is insufficiently aware of differences in technology, customs, attitudes, or fashions between two different historical eras.
The intentional use of older, often obsolete cultural artifacts may be regarded as anachronistic. For example, it could be considered anachronistic for a modern-day person to wear a top hat, write with a quill, or carry on a conversation in Latin. Such choices may reflect an eccentricity, or an aesthetic preference.
A parachronism (from the Greek "παρά", "on the side", and "χρόνος", "time") is anything that appears in a time period in which it is not normally found (though not sufficiently out of place as to be impossible).
This may be an object, an idiomatic expression, a technology, a philosophical idea, a musical style, a material, a custom, or anything else sufficiently closely bound to a particular time period as to seem strange when encountered in a later era. They may be objects or ideas which were once common, but are now considered rare or inappropriate. They can take the form of obsolete technology or outdated fashion.
Examples of parachronisms could include a suburban housewife in the United States around 1960 using a washboard for laundry (well after washing machines had become the norm); or a teenager from that time period being an avid fan of ragtime music. Often, parachronism is identified when a work based on a particular era's state of knowledge is read within the context of a later era—with a different state of knowledge. Many scientific works that rely on theories that have later been discredited have become anachronistic with the removal of those underpinnings, and works of speculative fiction often find their speculations outstripped by real-world technological developments or scientific discoveries.
This differs from a prochronism, in which the object or idea has not yet been invented when the situation takes place, and therefore could not have possibly existed at the time. A prochronism occurs when an item appears in a temporal context in which it could not yet be present (the object had not yet been developed, the verbal expression had not been coined, the philosophy had not been formulated, the breed of animal had not been developed, the technology had not been created).
Politically motivated anachronism
Some writings and works of art promoting a political, nationalist or revolutionary cause use anachronism to depict an institution or custom as being more ancient than it actually is. For example, the 19th-century Romanian painter Constantin Lecca depicts the peace agreement between Ioan Bogdan Voievod and Radu Voievod—two leaders in Romania's 16th-century history—with the flags of Moldavia (blue-red) and of Wallachia (yellow-blue) seen in the background. These flags date only from the 1830s. Here anachronism promotes legitimacy for the unification of Moldavia and Wallachia into the Kingdom of Romania at the time the painting was made.
Art and literature
Anachronism is used especially in works of imagination that rest on a historical basis. Anachronisms may be introduced in many ways: for example, in the disregard of the different modes of life and thought that characterize different periods, or in ignorance of the progress of the arts and sciences and other facts of history. They vary from glaring inconsistencies to scarcely perceptible misrepresentation. It is only since the close of the 18th century that this kind of deviation from historical reality has jarred on a general audience. Sir Walter Scott justified the use of anachronism in historical literature: "It is necessary, for exciting interest of any kind, that the subject assumed should be, as it were, translated into the manners as well as the language of the age we live in." Anachronism can also be an aesthetic choice. Anachronisms abound in the works of Raphael and Shakespeare, as well as in those of less celebrated painters and playwrights of earlier times. Anachronisms can exist in ancient texts. Modern archeology can show the impossibility of these anachronisms and identify texts that have been updated to incorporate more modern concepts, such as camels in the Book of Genesis. Carol Meyers says that these anachronisms can be used to better understand the stories by asking what the anachronism represents. Repeated anachronisms and historical errors can become an accepted part of popular culture, such as Roman legionnaires that wear leather armor.
Comedy fiction set in the past may use anachronism for humorous effect. One of the first major films to use anachronism was Buster Keaton's The Three Ages, which included the invention of Stone Age baseball and modern traffic problems in classical Rome. Comedic anachronism can be used to make serious points about both historical and modern society, such as drawing parallels to political or social conventions.
Even with careful research, science fiction writers risk anachronism as their works age because they cannot predict all political and technological change. For example, many books and films nominally set in the mid-21st century or later refer to the Soviet Union, defunct in 1991, or to Saint Petersburg in Russia as Leningrad. Such conflicts can be retconned by positing a return to the former state, a new Soviet Union emerging and the city's name changing back to Leningrad. Star Trek, which has a history of predicting technology, has suffered from future anachronisms. Instead of retconning these errors, the 2009 reboot retained them for consistency with older franchises. Buildings or natural features, such as the World Trade Center in New York City, can become out of place once they disappear.
Language anachronisms in novels and films are quite common, both intentional and unintentional. Intentional anachronisms inform the audience more readily about a film set in the past. Language and pronunciation change so fast that most modern people (even many scholars) would have difficulty understanding a film with dialogue in 17th-century English; thus, we willingly accept characters speaking an updated language. Similarly, modern slang and figures of speech are often used in these films.
The detection of linguistic anachronisms can form part of the scholarly discipline of 
Unintentional anachronisms may occur even in what are intended as wholly objective and accurate records of historic artifacts, because the recorder's perspective is conditioned by the assumptions and practices of his or her own times. An example is the attribution of historically inaccurate beards to various medieval tomb effigies and figures in stained glass in records (both drawings and written descriptions) made by English antiquaries of the late 16th and early 17th centuries. Working in an age in which beards were in fashion and widespread, the antiquaries seem to have subconsciously projected the fashion back into an era in which it was rare.
In historical writing, the most common type of anachronism is the adoption of the political, social or cultural concerns and assumptions of one era to interpret or evaluate the events and actions of another. The anachronistic application of present-day perspectives to comment on the historical past is sometimes described as presentism. Empiricist historians, working in the traditions established by Leopold von Ranke in the 19th century, regard this as a great error, and a trap to be avoided. Arthur Marwick has argued that "a grasp of the fact that past societies are very different from our own, and ... very difficult to get to know" is an essential and fundamental skill of the professional historian; and that "anachronism is still one of the most obvious faults when the unqualified (those expert in other disciplines, perhaps) attempt to do history". Anachronism in academic writing is considered at best embarrassing, as in early-20th-century scholarship's use of Translatio imperii, first formulated in the 12th century, to interpret 10th-century literature. Genuine errors will usually be acknowledged in a subsequent erratum.
The use of anachronism in a rhetorical or hyperbolic sense is more complex. To refer to the Holy Roman Empire as the First Reich, for example, is technically inaccurate but may be a useful comparative exercise; the application of theory to works which predate Marxist, Feminist or Freudian subjectivities is considered an essential part of theoretical practice. In most cases, however, the practitioner will acknowledge or justify the use or context.
- Antikythera mechanism
- Invented traditions
- Society for Creative Anachronism
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