Byron York

That's certainly not the way experts talk about the issue. When discussing projects like offshore exploration, engineers often use the phrases "PF," which stands for probability of failure, and "CF," for consequences of failure. The Deepwater Horizon disaster was a classic low-probability, high-consequence event. Even with good safety procedures, strange combinations of human error, mechanical failure and sheer bad luck can combine to cause a devastating accident.

"There has been a constant improvement in safety, but you can never say that a very low probability but very high consequence event is impossible," Arnold says. "You can never say that."

That's the point that comes back over and over in discussing offshore oil drilling. Even though technology has gotten better and better over the years, you can't say it is absolutely safe.

Yet Obama said just that. It could be that one or more of his advisers explicitly told him that drilling would be absolutely safe. If that's the case, he got bad advice.

Or it could be there were mistakes in communication as the assessment of risk made its way through the bureaucracy to the president's ears. Say a government official who specializes in calculating risk determines that there is a one in 10,000 chance, or one in 100,000 chance, or one in 1 million chance of something happening. When the information goes from the specialist to his boss, and then up another level or two, what had begun as a specific risk assessment becomes simply "safe." Then maybe it becomes "absolutely safe."

"By the time it gets to the green team and then to the president, you get these horrible distortions," says Bea.

Of course, there's a third possibility. Since the Deepwater Horizon explosion, Obama has taken a lot of heat from liberals who never liked his pro-drilling decision in the first place. Maybe he used the words "absolutely safe" to deflect blame and make himself look a little better in retrospect.

That would be troubling, but not as troubling as the possibility that Obama actually believed his own claim. What would that say about the president many commentators have described as brilliant?

Byron York

Byron York, chief political correspondent for The Washington Examiner