Colleen Atwood

Costume, hair and makeup can tell you instantly, or at least give you a larger perception of who a character is. It's the first impression that you have of the character before they open their mouth, so it really does establish who they are.

By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.