The second pillar of Wikipedia is: "Wikipedia is written from a neutral point of view". As a concept, it is very simple, but in practice it can be much more complicated.
Wikipedia is intended to convey information in an even-handed way, without advocating for one viewpoint or another. In math and science, where there is widespread consensus, this is easy. But in politics, business or the humanities, this is much harder—not just writing in a neutral tone, but also selecting the right details.
How much emphasis does one viewpoint deserve to be mentioned compared to another? Are there certain views which do not deserve mention at all? Wikipedia has many rules attempting to help editors find the best answer, but the rules can't predict every dispute. For that, Wikipedia depends on finding consensus.