Advance warning: This post contains spoilers.
Last week's episode of Lost ("Flashes Before Your Eyes") was a well-told time travel story that made some strong statements about free will, divine providence, and divine predetermination. Apparently, when Desmond turned the failsafe key in the season two finale, he traveled back in time. This episode gives a clever twist on the show's usual flashback structure—we get scenes from Desmond's past, but throughout them he is aware (or at least partly aware) of his future on the island. Desmond relives the days surrounding his biggest regret in life—not marrying his lost love Penelope. It's when he attempts to rectify that mistake that things get really interesting.
The moment of truth comes when Desmond attempts to purchase an engagement ring for Penelope. As the event originally occurred, he had second thoughts and didn't make the purchase. The second time through he pulls out his wallet, and the jeweler, Ms. Hawking, becomes an avatar of the divine will:
"This is wrong. You don’t buy the ring. You have second thoughts. You walk right out that door. . . And if you don’t do those things, Desmond David Hume, every single one of us is dead."Later in their conversation, Desmond and Hawking witness an accident in which a pedestrian is killed by falling debris. When Desmond asks why she did not warn the victim, she lays out the shows metaphysic of free will:
"Had I warned him about the scaffolding, tomorrow he’d be hit by a taxi. If I warned him about the taxi, he’d fall in the shower and break his neck. The universe, unfortunately, has a way of course correcting. That man was supposed to die. That was his path. Just as it’s your path to go to the island. You don’t do it because you choose to, Desmond. You do it because you’re supposed to."In the Lost universe, there is a way that things are "supposed to be," and the path can be temporarily diverted, but never completely changed.
Hawking's sense of apocalyptic urgency regarding Desmond's path echoes similar ideas in Donnie Darko whose time-traveling protagonist's actions create a "divergent universe" doomed to collapse. And the idea of a guiding plan is similar to that presented—albeit in much more uplifting terms—in Quantum Leap. Lost takes a profoundly pessimistic view of its own understanding of free will, though. Events are predetermined, and the characters don't like it one bit. But Desmond has been granted the ability to see the future, and (as we learn in the episode's conclusion) he's already used this ability to change the predetermined course of events on the island. Donnie Darko and Quantum Leap aside, predetermination isn't a popular idea in SF, which, as a generally humanistic genre, tends to support free will as an absolute. I see Desmond's story unfolding as a re-casting of the story of Abraham and Isaac in which Abraham, rather than submitting to the divine will, struggles against it to reclaim his free will.
For more on messianism and providence in Quantum Leap and Donnie Darko, see chapter four of The Gospel According to Science Fiction.