Never say never. I'd agree with never use force on another person unless it's used (or legitimately threatened.) Use caution and minimum force necessary when you do, and especially watch those encounters when there's a great disparity in size. Many years ago when I first started working security I would have agreed with the statement "Act like a lady, I'll treat you like a lady. Fight like a man and I'll fight you like a man." But later on I realized that was the wrong way to look at it, for several reasons. I evolved to "Act civil, I'll treat you civil. Act like a threat and I'll treat you like a threat." Part was from scrapping with a few Army/Marine chicks who counted on me being chivalrous and they threw the first punch. But, I had each of them by 6-9" and 50-100 pounds and was trained myself.