[molticrystal]

I thought knowledge, at least the best type comes from primary sources and from repeatable experiments with explicit premises as much as possible. This makes it sound like all knowledge is hearsay. If it is, what is the point of a place like Wikipedia or even an encyclopedia?

[denton-scratch]

Indeed, the best type of knowledge comes from primary sources and original research. But those also produce an awful lot of not-knowledge.

Wikipedia's approach to sifting the knowledge from the not-knowledge is to prefer reliable secondary sources, i.e. sources deemed capable of telling the difference, mainly because they have a reputation for good editorial control. It's far from an ideal touchstone; but relying on "experts" is worse, because who's an expert? You need experts to identify experts, which is circular.

"Reliable secondary sources" doesn't amount to hearsay.