[I]magine that you are observing a trial for murder. Most of the evidence goes against the accused (who allegedly murdered a 5-year-old girl). The girl's father sits anxiously, awaiting the verdict; he testifies that he witnessed the murder personally, but various other strands of evidence exist which create some doubts.
After witnessing the whole trial, a definite conclusion about the evidence strikes you: the accused is probably guilty, but not guilty beyond a reasonable doubt. And the jury, apparently, felt the same way: they regretfully emerge from deliberations and proclaim the defendant "not guilty."
Suddenly, the enraged father whips out a concealed hand gun and aims it at the smiling acquited defendant. He shoots and kills the defendant. Now the question arises: what, if anything, may be justifiably done to the father?
I go on:
Imagine you were the bailiff for the trial and you saw the father draw his gun; should you shoot and possibly kill the man who probably is not a murderer, in order to save a man who probably is? Only the preponderance rule lets us escape the bizarre conclusion that we should kill the man who is less likely to be a murderer in order to save the man who is more likely to be a murderer.