Some science fiction films take us to different worlds or alternate realities, or offer visions of the future. In each of these new worlds, certain new rules apply. Sometimes the rules are pretty simple and can be easily and clearly established, as in Star Trek or District 9. Other times the rules are exceedingly complex and raise a million questions, as in the new Surrogates, which is based on a comic book by Robert Venditti and Brett Weldele. In this future world, humans can strap themselves into a chair, plug themselves into a bunch of sensors and have complete control of an artificial being, including movement, speech and senses. This artificial being can then go out into the world to perform daily tasks, while the real person is safe at home, never risking getting hit by a car or falling down a manhole.

From there, things get sticky. A narrator explains to us that 98% of the population uses the surrogates, and later a character says something about a "billion" users. Last time I checked, a billion was only about 20% (or less) of the population. Plus, how much do these surrogates cost? Can all the poor people of the world afford them? We do get to see a few things like a surrogate bringing home food for its owner to eat, and other points in which surrogates freeze up while their owners use the bathroom, but just how do people go about their daily lives? Some of the users look like they're in pretty bad shape, sitting in their chairs. Is using a surrogate physically or emotionally addicting? Do their muscles atrophy? Do they take showers? Do they ever get together to have sex? Has the population gone down because of too much surrogate sex and not enough human sex?

Then there are the physical aspects. Some of the surrogates seem to have super-powers. One of them, belonging to an FBI agent, jumps from the roof of a moving car to the roof of a moving bus. Is this something that just anyone can do, or is it specific to the Bureau? Some of the surrogates seem pretty sturdy, but others can be taken down by a couple of bullets, or by poking them in the right spot at the back of their skull. Just how strong are they? The movie shows us images of very plain-looking military surrogates, but in another scene, non-surrogate human soldiers are dispatched into a scene of violence. Why? These are just some of the things I want to know, and a movie just about a day in the lives of the surrogates and their owners would be pretty interesting to me, but Surrogates is instead about a murder, something unusual and unique in a safe, risk-free world.

A man meets a blonde at a nightclub and vacates to the back alley for some nookie. There, a man on a motorcycle shoots them with something that knocks them down and burns out their eyes. Unfortunately, it turns out that the surrogate fail-safe device has not kicked in and that the two human operators have also died. The girl turns out to have been operated by a fat guy, and the guy turns out to have been the son of Dr. Lionel Canter (James Cromwell), the inventor of the surrogates. We learn that Canter originally developed them to give the disabled an advantage in life, but he was later fired by the giant corporation, VSI, that continues to manufacture the surrogates. Canter now lives as a recluse.

FBI agents Greer (Bruce Willis) and Peters (Radha Mitchell), who of course work their dangerous job in surrogate form, turn up to investigate. They discover the existence of a dangerous weapon, and they find their suspect. A chase scene leads Greer to the compound of "The Dreads," a small community/cult that refuses to have anything to do with the surrogates. They are led by "The Prophet" (Ving Rhames), who promises a rebellion. Greer sticks his nose in the wrong place, and his surrogate is destroyed, forcing him to finish the case in his human form. He quickly collects a series of painful cuts and bruises to remind him of his humanity; he eventually decides that he'd like to see his wife (Rosamund Pike) in person for once, and that maybe this whole thing was a bad idea.

Director Jonathan Mostow (Terminator 3: Rise of the Machines) turns in a fairly clean, tight film that looks great -- especially the weird, scrubbed, polished look of the surrogates -- and with the requisite number of car crashes and helicopter explosions. And it's pretty certain that he favors the idea of humans over the artificial alternative; it's a potent theme in this age of iPhones and Blackberries and whatnot. But it's more of a thriller than a cautionary tale, and it doesn't go very deep in either direction. (Steven Spielberg's sci-fi double-bill from earlier in the decade, A.I. Artificial Intelligence and Minority Report, took on all these ideas with a great deal more thoughtfulness and skill.) Ironically, what's really missing from Surrogates is the human element; the movie has no concept that some people might see both the good and the bad in the surrogates. Instead it assumes that all flesh-and-blood individuals are either for or against them, like a digital switch that can be flipped from "1" to "0." We humans deserve better.