Say a crime has been committed. You are a detective and your task is to determine who committed the crime. Who should be charged with this crime? The thing you do is try to tell the story of the crime, given the evidence, in such a way that all the pieces fit together. You have some idea of how the crime was committed. Say it was a robbery. You have some account of the motive. The criminals, whomever they were, thought there was a lot of cash collected on site on that day. You have some idea of how it was done. There must have been an insider who gave the thieves information. That’s the only way, say, that they could have obtained access to the actual cash at a time when it was most vulnerable. And you have a list of suspects who were available, people without alibis, who might have done the deeds.