[OT] is there any theory behind (|) being false?

[Zhang Weiwu <zhangweiwu@realss.com>]

Quote from RFC 4526:
> An 'and' filter with zero elements always evaluates to True.  An 'or' 
> filter with zero elements always evaluates to False.

My question is, is there any theory this decision is based on, or is it 
randomly chosen?

Why not (&) being false, and (|) being true?

Or more specifically, we know 'FALSE && NULL' is FALSE, we know 'TRUE || 
NULL' is TRUE, but is there reason 'NULL && NULL' being true and 'NULL || 
NULL' being false?

Thanks:)