They won’t, there should be at least one, in the words of Carol O’Conner, dingbat on the jury.
All the rest have to say to the dingbat is "are you absolutely sure he's guilty. Because if you have a reasonable doubt, we've got to say, not guilty."
Furthermore, they could say, "show us the evidence you are using to come to the absolutely guilty conclusion."
And of course, there isn't any.