ON ACTING: Bright in Life, Stupid on Stage
I find that actors make that erroneous choice for one of the following wrong reasons: (1) the actor wants to protect herself in performance from the personal emotional shocks of surprises, discoveries, reversal of fortunes that can occur when she, as the character, unknowingly moves toward climax of the scene without protective foreknowledge (if she knows everything in advance, there are no negative emotional surprises possible); (2) the actor wants the audience to show how analytically smart the actor is: “I—my character—knew all the time what was going to happen; aren’t I appealingly bright, all-knowing and all-wise character (read: actor)?”; (3) the actor is insecure about his own everyday intelligence and doesn’t want to the audience to think she is stupid because she is playing a character stupid about his destiny in a scene.
I generally find that generally only an intelligently secure actor can best play a dumb character, a morally brave actor can best play an immoral character, etc. The greatest irony that often occurs in the lives of actors is that they live their offstage lives filled with drama: chaotic lives filled with surprise, shock, discovery and reversals; then, when they approach a role, they play the character as all wise and knowing.
I would advise actors: have a little foresight, foreknowledge and reasonableness in your everyday lives, and bring deep reservoirs of unknowing-ness, naivete and drama to your character lives! It will make your life happier, and your acting much more exciting!