It’s a horrific story: a man looks on as the car carrying his wife and son sinks beneath the surface of a flood-swollen river. He jumps into the water and is able to pull his wife free but can’t reach his son. What to do — keep struggling and try to reach his son, or use his energy to ensure his wife”s survival? A recent AP story described the dilemma:

[New Zealander Stacy] Horton said he arrived at the crash scene less than two minutes after the accident to hear his wife screaming in the darkness and to see his son’s friend and the family dog scrambling up the bank. His son Silva was trapped inside the submerged station wagon.

He tried to dive down to the vehicle, which was nose down but with the tail lights burning more than 3 feet (1 meter) below the surface, he told the Dominion Post newspaper.

“I tried to get down and get him but I couldn’t – it was just too deep. And Vanessa was going under,” Horton told the newspaper.

“I made a call to pull my wife to safety. I looked back and I could see the tail lights but it was too far and I couldn’t get him,” he said.

“Instead of going down and risking my life as well as my wife and son’s, I chose to take V(anessa) back and sat on the shore praying. It was all I could do,” a distraught Horton said.

Recourse to prayer is a common theme in stories of life-or-death peril. Time and again, people struggling to survive find that they’ve run out of options and turn to hope of divine intervention. But is praying something that can actually help to materially improve one’s odds?

Some people believe that it can. Indeed, earlier this year writer Ben Sherwood published a book entitled The Survivors Club: The Secrets and Science that Could Save Your Life, in which he states emphatically that prayer has saved many people from the jaws of death: “Faith,” he writes, “is your greatest comfort and mightiest weapon.”

But is this really science that can save your life? There’s no solid, peer-reviewed evidence that praying for heavenly assistance does any good. On the contrary: a 2006 study found that being on the receiving end of other people’s prayers did not help hospital patients recover. The fact that even highly religious people tend to pray as a last resort, rather than a first one, would suggest that no one really places much, um, faith in its efficacy.

As a matter of law, praying for something is not considered equivalent to actively making it happen. If you pray for someone’s death, and then they die, you will not be held culpable of murder (unless, of course, you reinforced your prayers with a few swift blows with a lead pipe). Neither is prayer considered a responsible option in trying to avert disaster. This past March, an Italian court found a Tunisian pilot guilty of manslaughter in the matter of a 2005 crash in which his plane ran out of fuel off the coast of Sicily. According to the AP report, Chefik Gharbi ” lost control of the situation, ceded command of the plane to his co-pilot and began praying.” Sixteen people died in the resulting crash.

Gharbi “is convinced that he did all he could to save as many lives as possible,” his defense lawyer, Francesca Coppi, was quoted as saying by Corriere della Sera. “Faced with danger, he evoked his God just like anyone of us would do.”

The court disagreed with Gharbi’s reasoning, and sentenced him to 10 years  in jail.