THERE must be a rational explanation for all the supernatural phenomena on television. There must.

Because it is weird, and even a little freaky, that so many shows this season prey on the paranormal. Vampires have day jobs as detectives, store clerks reap souls for the Devil, reporters time-travel to get their stories straight, cheerleaders walk through fire and people of all kinds talk to dead people, sometimes quite chattily. Even reality television is getting swept up in the surreal: On Oct. 24 NBC will unveil “Phenomenon,” an “American Idol”-ish competition for illusionists and mentalists, with Uri Geller and Criss Angel as judges.

On the CW show “Supernatural” strapping young ghostbusters hunt down evil spirits armed with a Colt revolver and holy water, displaying the kind of weary nonchalance that “CSI” investigators bring to a crime scene. “So, Bobby,” one of the heroes asked in the season premiere, “what do we have here, a biblical plague or what?”

People used to believe in magic until science began proving them wrong. For a while crime shows made a religion of forensic science. It’s possible that television took forensics — all those bloodstain spatters, DNA swabs and acoustic reflectometry probes — as far as it could go. Now the only novelty left for the police procedural genre is a return to magic.

Or worse: It could just be inhuman nature.

Nobody really knows where network executives come from or where they go after being fired. Perhaps those neatly groomed suits marching in lock step through Burbank are themselves the undead, demons, witches and vampires who suck the blood of Nielsen pollsters, turn viewers into zombies and howl at the Moonves. They are taking over the planet one show at a time.

Because there are, after all, an unnatural number of supernatural series at the moment. “Lost” is about to enter its fourth season (it began in 2004). “Medium” and “The Ghost Whisperer” have been on the air since 2005. “Heroes,” which began last year, showcases genetic mutants who use their special powers to save the world from comic-book apocalypse.

And this season there are still more supernatural heroes, and some of them are putting normal detectives out of work. The protagonist of “Moonlight” is a vampire with a day job as a private eye. He relies on a dealer to supply him with blood because he has a conscience: too scrupulous to bite the necks of innocent women and children, too fastidious to drink directly from a blood bag. (After his supplier brings him a pint, he pours it into a wine glass.)

“New Amsterdam,” a show Fox plans for midseason, has as its lead character a New York City police detective who is secretly immortal. As a soldier in the Dutch colony of New Amsterdam in 1642 he rescued an American Indian girl from a massacre and was rewarded with eternal life. (He is streetwise because he knew the streets of New York back when they were wagon trails.)

And HBO is preparing “True Blood,” a series by Alan Ball, the creator of “Six Feet Under,” about vampires who can live off synthetic blood made in Japan.

It is true that vampires have a lasting cachet. Almost every generation has tapped into it, from the 1960s “Dark Shadows” to the 1990s “Buffy the Vampire Slayer.” But this season networks are seeking an occult following in all sorts of places. ABC has “Pushing Daisies,” a series about a piemaker-turned-detective who can raise the dead long enough to ask them whodunit. NBC’s “Journeyman” is about a newspaper reporter who travels through time, though unfortunately he returns only to his own past, not more interesting destinations like King Arthur’s court or the Salem witch trials. “Reaper,” on CW, is a comedy about a clerk in a discount megastore whose parents sold his soul to the Devil.

Right now Satan appears to be more of a draw than his opposite; only “Saving Grace,” a TNT drama about a dissolute police detective (Holly Hunter) who is visited by a country-western angel named Earl, hints at a benevolent, all-powerful God. On “The Ghost Whisperer” Jennifer Love Hewitt plays a woman who helps dead people transition to the Other Side, guiding them to a hazy white light. But otherwise there isn’t much of a religious message to the show. It’s more interested in spooky spirits than spirituality.

That wasn’t the case a few years ago. In the aftermath of 9/11 many series tried to tap into what appeared to be a religious renewal. In 2005 three different series were centered on a heroine who receives holy instructions: God talked to the heroines of “Joan of Arcadia” and “Wonderfalls,” while in “Tru Calling,” a young woman working in a morgue found that she could talk to the dead and relive the past to right wrongful deaths. That same year NBC even experimented with a faith-based mini-series, “Revelations,” about a scientist and a nun who investigate signs of encroaching Armageddon. None of these shows found the kind of mass audience that turned “Touched by an Angel” into a major hit from 1994 to 2003. Networks returned to the more rewarding topics of sex and violence. Now, however, they are adding a touch of the paranormal. (Magical powers have limits, however. Even the most mind-bending supernatural feats cannot bring a moribund show like “Journeyman” back to life; “Moonlight” is a bore as well.)

Trends, like zombies, tend to rise again, and certain periods have been marked by an increased fascination with the occult. It’s possible that now, when the world seems besieged by perils of our own creation, from global warming to weapons of mass destruction, people seek a higher scapegoat: supernatural forces that are beyond our ken and not our fault.

But the paranormal does have a pattern of springing up at times of deep pain or confusion.

After the American Civil War grieving relatives seeking to reconnect with their lost love ones turned to all kinds of unorthodox practices, from soothsayers to Kirlian photography, which claimed to capture the subject’s supernatural aura. By the end of the 19th century, when Darwinism and other scientific advances began contradicting some tenets of organized religions, people as seemingly rational as William James and Arthur Conan Doyle became intrigued with even the silliest forms of spiritualism. Ouija boards and séances were the “Heroes” of their time: prime-time entertainment that opened a door to the magical and the occult.

In the 1960s television mostly played the supernatural for laughs in sitcoms like “Bewitched,” “I Dream of Jeannie” and “My Favorite Martian.” The conceit of those shows was that all the powers of the occult or outer space were harnessed to accomplish the most mundane tasks: — making sure dinner with the boss goes smoothly or keeping nosy neighbors from noticing the levitating bed. (It’s hard not to interpret those shows, with all their constrained unconventionality, as metaphors for the social repressions of the time.)

But there were less comic variations, from “The Twilight Zone” and “The Outer Limits” to “Dark Shadows” and “Alcoa Presents: One Step Beyond.” In the 1990s “The X-Files,” which teamed two F.B.I. agents —one a skeptic, the other a believer — to investigate paranormal happenings, was a watershed show. That series directly addressed the question of who or what is out there? And is it real? Most shows before “The X-Files” and after posited the supernatural as either silly or serious, but unquestioned.

At the moment television is doing both, which again could be a rather damning statement about our times or a sign that the television industry is controlled by a cabal of the damned and the undead, intent on airwave domination.

It is certainly suspicious that on comedies and dramas, vampires or the Devil’s henchmen infiltrate almost every profession, from store clerk to homicide detective. Only the television executive is depicted as normal, or as close to it as Alec Baldwin on “30 Rock” can be.

Surely that is the most paranormal phenomenon of all.