εἰ δὲ μή [7 verses](conj particles) This construction  means "otherwise." The three words literally "if however not." The "if" here expresses a condition but it means nothing regarding whether that condition is not when used with the subjective negative. The Greek word "but" means "but," "however," and "on the other hand."  It joins phrases in an adversarial way. Since it always falls in the second position, translating it as "however" often captures its feeling better.  The negative used here is the Greek negative of a subjective opinion, commands, and requests. It is the negative used in "if" phrases. -- The "else" here comes from three Greek words that literally mean "if however not." This is usually translated as "otherwise" or, in the KJV, as "else."