Stale Bread

How old does an argument have to be before it can assume the de facto status of being foundational?  Before it can just be assumed as a given?

How popular must it be with philosophers, serious theologians, or John Q Public before it simply becomes the truth?

Can you build arguments upon layers of previous arguments - a philosophical Stratum Ex nihilo?

Or, in the end, do you always have to ground your arguments in some factual observation about reality? 

The Arrow of Time

What's responsible for the arrow of time?  There's a lot of physics and philosophy on the subject including concepts that suggest that time isn't an arrow at all.  But in at least one sense I think it's safe to say that time is an arrow - at least for sentient beings.  Cognition, requires an accumulation of information that must be converted into knowledge.  That's a temporal process.  It requires a forward sequence of events.   Any learned behavior, requires past experiences that lead to lessons learned.  It is impossible to create a learning model that doesn't involve time.  Sentient beings perceive the passage of time in universe within a framework of prior events that define historical contexts.  What I ate last night, what I saw on TV this morning, what I read on Saturday, etc. , the framework we use to contextualize our existence.  Thoughts?