Why ten documents answer better than one

A brain with one document in it is a search box with better manners. Ask it something the document covers and it quotes the document. Ask it anything else and it tells you, politely, that it does not know. This is correct behaviour and it is also disappointing, and for a while the obvious fix looked like a better retriever.

It was not. The fix was more documents — specifically, documents that do not agree with each other.

One source cannot be weighed

When a brain holds one account of something, that account is the answer. There is nothing to weigh it against, so the brain reproduces it, hedge for hedge. When it holds four accounts written eighteen months apart, all four come back and the interesting work starts: the answer has to say which one is current, which was superseded, and what the owner has said since.

What to add next

If a brain is thin, the documents worth adding are not more of the same:

• Something you wrote that you now partly disagree with.
• A transcript, where you are answering rather than presenting.
• The reference you keep sending people, even though you did not write it — declared as someone else's, so it never becomes your own words.
• Anything dated.

The last one matters more than its position in this list suggests. Most of what makes an answer feel considered is the brain knowing which of two true things is the more recent.