On Person of Interest, the Machine is able to accurately predict when a person is about to be murdered. Thanks to the information provided by the highly advanced artificial intelligence, John Reese (Jim Caviezel) and Harold Finch (Michael Emerson) are able to intervene in various premeditated murders in New York City.
In the CBS series, it was explained that, as a result of 9/11, Finch designed the Machine so that the U.S. government would have a way of identifying acts of terror before they happened. However, Finch and his best friend Nathan Ingram (Brett Cullen) discovered that the Machine does its job even better than intended; it’s able to predict both terrorist attacks and domestic crimes. Unfortunately, though, the government decided that it didn’t have the time nor the resources to devote toward preventing these murders. Since this information was ignored, Finch used his backdoor to the Machine and picked Reese to be his partner in solving these crimes.
As for how the Machine manages to make these predictions, it’s able to achieve this through the massive amounts of data it has access to. It’s tapped into satellites and camera feeds everywhere. As Finch says, the Machine “sees everything” and keeps track of bank and phone records, and much more. The Machine sifts through all this information at once, and is programmed to pick up on clues that may suggest someone is about to commit murder. Exactly how it does this is revealed by paying close attention to the Person of Interest intro, which shows the Machine listening in on phone calls.
The Machine notices when relevant keywords like “kill” are used in phone conversations. Of course, most exchanges with these words don’t actually point to murder, but the Machine can observe through stress levels if someone has serious, violent intentions. It also examines web searches, purchase histories, criminal records, incoming and outgoing calls, and surveillance footage. If someone is planning a murder, chances are the Machine will know about it ahead of time by taking a thorough look at a person’s activities, including what they bought, who they’ve talked to and what they’ve said, and other potentially suspicious activities. Once it makes a prediction, it sends Reese and Finch a social security number of either the perpetrator or the victim, but never both.
Flashbacks of Finch’s past provided insight into how he got the Machine to be so effective. It never would have been able to know the difference between a trivial matter and a real murder if Finch hadn’t taken extensive measures to ensure that the Machine had a deep understanding of people. He knew when he was designing it that it was necessary for it to know how people think if it was going to properly fulfill its purpose. The time that Finch spent creating a human element in the Machine had a lot to do with what made it so reliable, not only as a A.I. that predicts murders, but also as an ally.