That's a pretty simplistic view, no? You don't believe causing a death is different than not preventing other deaths? Or perhaps it is different, but there is a certain moral penalty for letting a person die, and this is less than the moral penalty for letting 5 die? What if instead of 5, it was just a pregnant woman (1.5?)

Admittedly, that question isn't my favorite, as both options are relatively passive. How do you feel about the situations where a more active role is required? Would you push the man over the railing to save 5?