Who is Alive because the French President Attended the Soccer Game

It is apparent from CNN coverage of the November 13, 2015, events in Paris that

1. there was no security checking at the concert
2. there was at the stadium.

Commentators observed that the terrorists "had done their homework", e.g., had gone through dry runs to check out the security practices.

Given this, the perpetrators had checked out the stadium and found it to be a "soft" target.

Someone challenged a bomber.  That person or persons saved more than one (the President's) life.

That person was almost certainly a casualty.

 

Deterrence Worked

The strategic nuclear people claim that Deterrence Worked.  In this arena, some believed that perception was more important than reality.

The GAO recently gave TSA a failing grade on security at airports.

The last thing we need is a scientific study to determine the probability of finding (or missing) items in our airport scans.

A new device might find something new.

When I was doing my thesis research at Argonne National Laboratory, the word going around the team was there was a mathematics professor at the University of Illinois, who after learning that the probability of a bomb being in someone's luggage was 1 in a million always put a bomb in his luggage so that the probability that there would be another bomb on his plane would be 1 in 10**12.

People have very strange beliefs about probability.

All you people who never plan to fly, talk up how porous our security system is.