Wikipedia:Presentism

Presentism, judging historical events by current standards, should be avoided. Instead, explain – without undue weight – what reliable sources have said regarding changed standards with respect to the topic.

In literary and historical analysis, presentism is the anachronistic introduction of present-day ideas and perspectives into depictions or interpretations of the past. Some modern historians seek to avoid presentism in their work because they believe it creates a distorted understanding of their subject matter.

Step 1 – avoid presentism from a Wikipedia editor's perspective
Historians argue against taking a presentist perspective when describing historical events. What certainly cannot be done is adding a presentist perspective to historical descriptions where such presentist perspective is not covered by reliable sources. Whatever you feel about a topic, don't add your personal presentist slant to Wikipedia articles.

Similarly, when the look and feel of a source is presentist, but no reliable source writes anything about that possible presentism in that source, don't add your opinion on the validity of the source to the Wikipedia article.

Adding presentism from a Wikipedia editor's perspective by omission – e.g. leaving out well-documented material because it would be "politically incorrect" by today's standards – should equally be avoided.

Step 2 – be aware that descriptions in reliable sources may be influenced by presentism
Any reliable source on a historical topic may take a presentist slant. There is no prejudice against using such sources in Wikipedia. The important point is to be aware whether and where such presentism kicks in, and act accordingly:
 * First the facts, then the opinions: Don't start adding author's opinions before the Wikipedia article contains the bare facts of what the authors are opining about.
 * Separate "description" from "reception": Don't leave readers guessing what part of the article is a bare description of the topic and what part of the article contains assessment and perception of the topic throughout time: often it is best to separate the two narratives: first have one or more sections devoted to the factual narrative (genesis etc.), the basic information explaining the topic, free of moral judgement; and separate that from the ensuing sections that explain how the topic was received: how, why and when it was appreciated and/or rejected or criticised.
 * Compare sources from different eras and backgrounds: Neither exclusively trust the most recent sources that pop up after a superficial Google search, nor exclusively dated sources (for instance archived at archive.org). Compare all types of reliable sources which usually helps in extracting the bare facts everyone agrees upon, and getting a clearer picture of the opinions that are linked to a certain period or background.
 * In-text attribution of presentist analyses: Attribute opinions that are possibly influenced by presentist prejudice in the body of the article: name author and era/background in the body of the article to put the presentism in perspective.
 * Don't unbalance the treatment of a topic towards presentist approaches: Even if a topic has many readily available sources that present a presentist approach, be aware that many more may have been published that are not simply available via internet (they may be in libraries, in Google books without preview, etc.) the balance of an article should take account of all reliable sources, not only of those available on the internet. And even then, don't shift the balance away from the description of the topic to a panoply of presentist interpretations.
 * Don't be wishy-washy about an interpretation a certain era gives to certain facts: When an attitude or a characteristic of a topic is morally condemned in a certain context and era (even if that era is the present), with significant coverage of that assessment in reliable sources, don't bowdlerize Wikipedia of such documented approach (of course, for biographies of living persons within the constraints of WP:BLP).

Step 3 – look for reliable sources that analyse changes in perception regarding the topic
Often the most useful sources in the context of presentism, that is those that analyse how the perception of a particular historical fact may have changed over time or may have been influenced by current moral standards, are those that are hardest to find. As such sources may offer a valuable perspective (and may reduce the need to list individual presentist comments derived from separate sources), it is best to look for such reliable sources that contain an analysis of the changing views, and include them in Wikipedia's coverage of the topic.

Although it is generally preferred to use such sources when available, it is also true that for most topics changed perceptions are a side-topic – don't let the side-topic take over the main topic as a WP:BALASPS consideration.

Shifting country names and boundaries
Such shifts have often occurred. For example, a person born in what is now Germany should not be said to have been born in Germany if the birth was before 1870, when Germany was formed. The name of the independent country of birth at the time of the birth should be given, for example, Thuringia, or for birth in a colony, of the colony, etc. The current country can be indicated by "in what is now..." or the like.

A politically incorrect nickname
Dvořák's 12th String Quartet was once nicknamed Nigger Quartet. There was some discussion whether such an obsolete nickname should be mentioned in Wikipedia while considered "offensive" by today's standards. Reliable sources were found that placed the use of the nickname in its historical perspective:

18th-century plagiarism
Tilge, Höchster, meine Sünden is a composition Johann Sebastian Bach copied from Giovanni Battista Pergolesi. A presentist approach would be to describe that in terms of copyright infringement and plagiarism. At the time, however, "copyright" still had to be invented, leave alone a legal framework to impose it. The technique Bach used when transcribing the composition is called parody. As Wikipedia's article on that topic explains the technique in its context, and sources on this particular composition generally avoid the "copyright" presentist slant, a piped link to the parody (music) article suffices, without any need to mention presentist approaches in the article on the composition:

Shifting attitudes
The 1984 college comedy film Revenge of the Nerds features a scene where, during a costume festive, one of the main characters steals the costume of his rival, wears it to pretend to the rival's girlfriend that he is the rival, and they proceed to have sex. Within the 21st century, this action would be deemed the equivalent of non-consensual sex and possibly rape, and there are modern sources that critically reflect on the scene in this way. However, at the time of the film's creation when attitudes towards sex were somewhat different, and within the film itself, the action is deemed normal and acceptable. In this case, the scene is described as shown in the film without any interpretation nor applying the more recent take, but within the film's reception, the concerns over this scene are brought up with attribution.