This is the question that I've been thinking about since the Penn State scandal broke. I'm trying to think about this in the most honest way I can. Since I'm a small woman, I don't think I would have tried to physically stop it, but then again, if it was my own child, maternal instincts would probably kick in and my rage would have no boundaries.
After my initial shock and horror, I would probably run. I know it sounds horrible, but while I was running, I would have my cell phone in hand, dialing 911. If I didn't have a phone, I would still run to find someone with a phone or a place where they had a phone and beg them to call police. I think anyone hearing the words, "I just saw a grown man raping a child," would call the police without question.
Let's say the rapist is someone I know. Would it change my reaction and actions? Would I hesitate to call the police because my friend/co-worker/acquaintance is the one doing an unspeakable act on a child? Seeing anyone I know in any capacity raping a child would change my feelings for them forever. I believe I would still make every attempt to call police.
I see myself as a good person, but if I allow someone to get away with something as heinous as raping a child without notifying authorities, I'm as evil as they are.