A Wikipedia article cannot establish the truth about its subject, but it must truthfully report the available knowledge on the subect. Uncertain statements must be qualified as such, and subjective claims attributed to their authors.
Note that while truthfulness of the article text is required to achieve NPOV, the articles also need to be complete and balanced.
Truthfulness is ensured by writing only statements that are true beyond reasonable doubt. To achieve this, the following techniques are used: