Wikipedia:No reliable sources, no verifiability, no article
To ensure verifiability, the presence of cited reliable sources in articles is non-negotiable. Wikipedia is an encyclopedia, and we are encyclopedists. We are not compilers of personal knowledge, we are compilers of published information. If there is no published information that discusses a topic, then Wikipedia is not the place to discuss that topic.
If an article does not have reliable sources, the information in the article is non-verifiable. Because verifiability is a non-negotiable requirement for an article, an article lacking reliable sources should be deleted. No reliable sources, no verifiability, no article.
Delete now, improve later
"Keep and improve" is a typical battlecry for users who believe that the topic of an article is worthy of inclusion in Wikipedia. Indeed, this may be the case, but an article completely lacking of reliable sources is likely a crock-pot of original research, none of which would remain if the article ever ascended to Featured Article status.
This doesn't mean that no article on the topic should ever exist! However, just because someday someone might write a valid, credible, verifiable article that meets Wikipedia policy does not mean that the inferior, invalid article should remain as a placeholder. Reliable sources are a requirement for an article, not an objective. So delete the article now and wait for someone to write a credible, sourced, verifiable article. Or, better yet, do it yourself!
As Wikipedia shifts its focus from growth to quality, it is important that we encyclopedists do not tolerate the presence of low-quality, unsourced material in our encyclopedia.
Why this is important
- Verifiability makes Wikipedia accurate and credible.
- Pages that lack credible sources tend to contain original research.
- The existence of nonverifiable pages encourages new Wikipedians to create the same (see Broken windows theory). It must be made clear that reliable sources are a requirement, not an option.
Jimbo Wales agrees
Specifically with regard to BLP
I can NOT emphasize this enough. There seems to be a terrible bias among some editors that some sort of random speculative "I heard it somewhere" pseudo information is to be tagged with a "needs a cite" tag. Wrong. It should be removed, aggressively, unless it can be sourced. This is true of all information, but it is particularly true of negative information about living persons. – Jimbo Wales, 16 May 2006 
I really want to encourage a much stronger culture which says: it is better to have no information, than to have information like this, with no sources. Any editor who removes such things, and refuses to allow it back without an actual and appropriate source, should be the recipient of a barnstar. – Jimbo Wales, 19 July 2006 
- Wales, Jimmy (2006-05-16). "Zero information is preferred to misleading or false information". WikiEN-l. Retrieved 2007-01-31.
- Wales, Jimmy (2006-07-19). "insist on sources". WikiEN-l. Retrieved 2007-01-31.