Is an encyclopedia necessarily entitled to neutrality?
Most encyclopedias claim to represent the knowledge of their time, so it is not surprising that they reflect common normative thoughts. One tends to say that an encyclopedia is inherently conservative.
The French Encyclopédie by Diderots and his collaborators in the mid 18th century was an exception, writes Jeff Loveland, and if later Encyclopaedia Britannica attacked France and its Revolution, this was a certain conservative statement. But only in later ages encyclopedias got an explicit political agenda, for example the Nazi version of Meyer 1936-1942. 
Another branch of non neutral encyclopedias were Christian works, with one of the oldest the Etymologiae by Isidor of Seville.This tradition goes forth to the 19th and 20th century with its Catholic encyclopedias. The Dutch De Katholieke Encyclopedie (1932) tells why a general encyclopedia does not suffice to a Catholic: ‘That impartiality – especially in an encyclopedia – is nonsense and even nearly dangerous needs hardly explanation. [...] numerous items cannot be judged without a firm basis.’ 
But what exactly is ‘conservative’ or ‘progressive’? Does this not primarily depend on the opinions of the critic? Harvey Einbinder tells us in The Myth of Britannica that some claimed that Britannica was pro-catholic, others that it was anti-church.  Some claim that German Wikipedia is terribly left-wing (Welt commentator Bettina Röhl), others that is a ‘Nazipedia’. Ulrike Spree wrote: ‘The neutrality weisenheimer is easily at risk to become a self-proclaimed judge about true and false and consequently also about good and wrong.’ 
To show how difficult it can be to determine the political point of view, let’s take the Universal history as an example. Its author Dennis de Coetlogon had a very polemical character; as he was a Catholic and advocated Jacobitism in 18th century England, he is usually considered to be a conservative. His biographer Loveland noted that Catholicism then was illegal, and that De Coetlogon was a Catholic ‘albeit an unorthodox and ecumenical one’. .
De Coetlogon in the Universal history often makes fun of Protestants for their anti-catholicism; he shows few sympathy for Calvinists because of their fanaticism and anti-monarchism. But he also criticizes the Inquisition and the corruption in Vatican. People telling ghost stories should be severely punished. He advocated the reunion of Western Christianity and tolerance for all religions, also for Jews. The English Jews De Coetlogon calls decent and ‘very good subjects’. Although it was not subversive, Loveland states: ‘For its audacity in questioning the orthodoxies of its milieu, especially in religion, the Universal history is ultimately most comparable to the Encyclopédie.’ 
Encyclopedias became less dependant from the views of a single author as they became the cause and property of publishing houses. In the 19th century, no encyclopedia gave up the goal of objectivity, says Spree, even the religious ones. They categorically excluded the possibility of the existence of several truths. Within this framework there ware several positions:
- Taking side: They claim to serve to the literate classes, to a specific denomination, to a political party (for example Wurm’s Social Democratic encyclopedia). They want to break monopolies of knowledge and set things straight but still claim a universal validity.
- Pluralism: Different groups of interests have their word in different articles, or in an article several positions are mentioned.
- Neutrality: An encyclopedia stands above the parties by a) referring to academical works, or by b) searching for the middle way. This is still no warranty against extremist positions, according to Spree. 
So also Wikipedia calls itself a neutral encyclopedia entitled to objectivity. Of course, Wikipedians are not so naive that they believe that there is perfect neutrality. But instead of some, who consequently want to drop the goal of neutrality, they try at least. Otherwise it would be difficult to write an encyclopedia collaboratively.
 Jeff Loveland: An Alternative encyclopedia? Dennis de Coetlogon’s Universal history of arts and sciences (1745). Voltaire Foundation, Oxford 2010, p. 179.
 Introduction. In: De Katholieke Encyclopedie. Proeve van bewerking tevens prospectus. Uitgeverij Joost v. d. Vondel, Amsterdam 1932 [p. 2].
 Harvey Einbinder: The Myth of the Britannica. MacGibbon & Kee, London 1964 (reprint 1972), p. 67.
 Ulrike Spree: Das Streben nach Wissen. Eine vergleichende Gattungsgeschichte der populären Enzyklopädie in Deutschland und Großbritannien im 19. Jahrhundert, Niemeyer 2000, p. 28.
 Jeff Loveland: An Alternative encyclopedia? Dennis de Coetlogon’s Universal history of arts and sciences (1745). Voltaire Foundation, Oxford 2010, p.p 193/194.
 Jeff Loveland: An Alternative encyclopedia? Dennis de Coetlogon’s Universal history of arts and sciences (1745). Voltaire Foundation, Oxford 2010, pp. 194-197, 200, 209.
 Ulrike Spree: Das Streben nach Wissen. Eine vergleichende Gattungsgeschichte der populären Enzyklopädie in Deutschland und Großbritannien im 19. Jahrhundert, Niemeyer 2000, pp. 316/317.