Truth should not be hard-coded but somehow emergent
I ran across an interesting statement in a post on the W3C Semantic Web email list by Jeremy J. Carroll, Chief Product Architect of TopQuadrant in reply to a post from John Sowa, that relates to truth in the context of the Semantic Web:
... truth should not be hard-coded but somehow emergent.
I would add that there may be many competing truths on any given issue and that the user will have to choose between competing value systems that each arrived at their own versions of the truth of an issue.
Each user may have their own preferred authorities and sources from which they may choose to select the appropriate value system.
All of this may evolve over time. Authorities and sources can change their minds. Underlying data can change. Calculations can change. Rules can change. Theories can change. Experiments can be re-evaluated or examined in a new light. The world can change. Authorities and sources can come and go and their influence can wax and wane. User preferences can change.
So, you cannot capture truth at a moment and hold it forever. You need to re-execute your query to determine the truth of some assertion at the time you need it. Of course, even the Semantic Web cannot give you the real truth, but merely the modeled truth, as it emerges and as it continues to evolve, even over time, with time being a variable required for determining the truth of a proposition.