>> With that model, a database would already have **all** possible answers
>> in it before all possible questions are asked.

Not all possible answers, but a provision to record any possible answer.

A DBMS derives new facts (query results) from a set of asserted facts (the
database). If the initial assertions are true and derivation rules are
consistent the derived facts are true (i.e. query results are correct).

Therefore as a deductive logic system, when required the DBMS must allow for
the derived facts to be recorded as needed, not that it should record all
possible derivations.

We already do this all the time using views, derived tables, CTEs etc.

>> And the answers are at a different level than the facts -- the old data
>> and meta data getting mixed together problem, the need to constantly
>> update the flags when the underlying facts changes, etc.

Conceptually the answers themselves are facts if the inference rules are
sound. It is we who assume a distinction due to limitations in our tools,
methods and languages.

Yes, the term "flag" carries certain baggage from CS history, but I fail to
see an argument to avoid a domain with two values, in general.

--
Anith