Wikipedia is a free online encyclopedia that anyone can edit. The site acknowledges that "citation of Wikipedia in research papers may be considered unacceptable, because Wikipedia is not a reliable source," and is prohibited by policy of many educational institutions(2). A related Wikipedia essay notes:


“Wikipedia is not a reliable source...information it contains at any particular time could be vandalism, a work in progress, or just plain wrong. Biographies of living persons, subjects that happen to be in the news, and politically or culturally contentious topics are especially vulnerable to these issues...There are many errors that remain unnoticed for days, weeks, months, years, or even for a decade. Therefore, Wikipedia should not be considered a definitive source in and of itself.”(2)


A 2018 study published by Harvard evaluated articles in Wikipedia and Encyclopedia Britannica to “compare bias in these two models in the context of contested knowledge, which involves subjective, unverifiable, or controversial information.”(3) They found that “Wikipedia articles are more slanted towards Democratic views than are Britannica articles, as well as more biased.”


Wikipedia cites its internal policy that “articles must be written from a neutral point of view, which means representing fairly, proportionately, and, as far as possible, without editorial bias, all of the significant points of view that have been verifiably published by reliable sources on a topic.”(4) The site nonetheless acknowledges that as it relies on volunteer editors, it is susceptible to the ideological bias of its contributors, which has been alleged particularly for the English language version. It cites research findings that “articles with smaller edit volumes by a little number of ideologically homogeneous contributors were more likely to reflect an editorial bias.”(5),(6)


Many have noted Wikipedia articles’ mainstreaming of left-leaning or even far-left media and organizations by neglecting or minimizing mention of ideological bias and controversies surrounding bias and false reporting. Wiki articles have tended to marginalize independent, right-center, and conservative organizations by prominently representing claims of ideological bias and criticism from competitors on the political left as if they were factual and unbiased.


The article “Inside Wikipedia's leftist bias: socialism pages whitewashed, communist atrocities buried” notes that millions rely on Wikipedia for information, which is ranked by Alexa as the “13th most popular website in the world,” and is given special placement in Google search results.(7) Yet Wikipedia co-founder Larry Sanger complained that “many Wikipedia pages have become merely left-wing advocacy essays.” He stated:


"The days of Wikipedia's robust commitment to neutrality are long gone. Wikipedia's ideological and religious bias is real and troubling, particularly in a resource that continues to be treated by many as an unbiased reference work.”(ibid)


An example is cited of Wikipedia’s main articles on socialism and communism, which span 28,000 words with mostly flattering claims. These pages “whitewash crimes against humanity” in the USSR and China and “fail to note any of the atrocities committed by other socialist and communist regimes, from Venezuela, Cuba, Nicaragua, Cambodia, or North Korea, among others.”(ibid) Rampant human rights violations and atrocities including the murder of an estimated 100 million people are relegated to “a stray link at the very end under a ‘see also’ heading.” Economics professor Bryan Caplan noted that “The omission of large-scale mass murder, slave labor, and man-made famines is negligent and deeply misleading.” Jonathan Weiss, a top-100 Wikipedia editor, noted that “the political pages have largely been taken over by editors with a political axe to grind.”(ibid) Edits to add balance have been “quickly erased by other editors.”



1. "Wikipedia: Academic Use." (accessed March 21, 2021). 

2. "Wikipedia:Wikipedia is not a reliable source." (accessed March 21, 2021).

3. Greenstein, Shane, and Feng Zhu. "Do Experts or Crowd-Based Models Produce More Bias? Evidence from Encyclopædia Britannica and Wikipedia." MIS Quarterly 42, no. 3 (September 2018): 945–959. 

4. “Ideological bias on Wikipedia.” (accessed March 21, 2021).

5. Greenstein, Shane; Gu, Yuan; Zhu, Feng (March 2017) [October 2016]. "Ideological segregation among online collaborators: Evidence from Wikipedians". National Bureau of Economic Research. No. w22744. doi:10.3386/w22744.

6. Holtz, Peter; Kimmerle, Joachim; Cress, Ulrike (October 23, 2018). "Using big data techniques for measuring productive friction in mass collaboration online environments". International Journal of Computer-Supported Collaborative Learning. 13 (4): 439–456. doi:10.1007/s11412-018-9285-y.

7. Lott, Maxim. “Inside Wikipedia's leftist bias: socialism pages whitewashed, communist atrocities buried.” February 18, 2021.