The presence or absence of “empty-full” determines if arts such as ba gua or t’ai-chi won’t work in real combat. The principle points out why some practitioners ARE effective in close-combat with their IMA. “Empty-full” allows the practitioner to move rapidly, and change position, between attackers that are closing quickly from different positions. However, when “empty-full” is absent, a defense is static, a “defense” will only work if the attacker stands still in one positIon. Combat is chaotic and attackers in a real fight do not stand still!