TO+WHAT+EXTENT

"Historian's opinion" is true only when considering...but not when considering...
 * Body P 1 = True
 * Body P 2 = True (historiography)
 * Body P 3 = False
 * Body P 4 = False (historiography)

This factor is necessary when explaining...but not sufficient to...
 * Body P 1 = Why Necessary (why is this factor important?)
 * Body P 2 = Why Necessary (why is this factor important)
 * Body P 3 = Why Not Sufficient (what other factors also contributed?)
 * Body P 4 = Why Not Sufficient (what other factors also contributed?)