With all the other things to target -- buildings, transit systems, to name a few -- why do Islamist militants keep returning to aircraft as a target? Defence studies professor Michael Clarke explains why.

This Slate column observes that U.S. businesses that cater to the mass affluent are reporting disappointing financial results. It sets out to explain why, and part of the answer is that "yuppie inflation" is rising faster than core inflation.

An excerpt from a commentary by Slate national correspondent William Saletan (h/t to The Tyee):

We're living in a liquid world. All the solid lines—states, borders, battlefronts—are melting. British Home Secretary John Reid made that point in a speech yesterday. Then he reassured Britons that their government, through tougher immigration control, was protecting them from terrorists, "many of whom come from far beyond our shores and have no real connection with our nation."

Nice try. According to reports, all 20 or so alleged conspirators arrested in the new plot are British citizens. Sealing your borders won't protect you.

So, what do we do? As Reid put it,

What happens when the threat to our nation, and hence to all of us as individuals, comes not from a fascist state but from what might be called fascist individuals? Individuals who are unconstrained by any of the international conventions, laws agreements or standards, and have therefore, unconstrained intent? Individuals who can network courtesy of new technology and access modern chemical, biological and other means of mass destruction, and who have therefore unconstrained capability?

The answer is, some of us die. And the rest of us grieve, but we go on, doing our best to fight the bad guys and heal the world. The grieving and fighting and healing never end the dying. "We are probably in the most sustained period of severe threat since the end of World War II," Reid observed. "While I am confident that the Security Services and Police will deliver 100% effort and 100% dedication, they can never guarantee 100% success."

That's the bottom line: We die. In a liquid world, you can't seal off evil. All you can do is fight liquid with liquid. You have to absorb the tragedy, flowing around and through it. You need the strength of a river, not a rock. You need resilience. You can't be untouchable, but you can be undefeated.

Reid ended his speech with a quote from Charles Darwin: "It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change." It isn't the individual who has to adapt and survive. It's the species.

This Globe and Mail analysis asks whether al Qaeda is back.

The Beeb rounds up what the Brit papers are reporting in their Friday editions on Thursday's 'bomb plot' arrests.

If you go to this CTV.ca story and click on the Kathy Tomlinson video item, what you'll learn that it's not that easy to blow a plane out of the sky. Plenty of planes have survived small explosions with minimal loss of life.

(On the other hand, The Globe and Mail headlined one story: Liquid-based explosives could easily down airliners. The paper has a story on a previous al Qaeda plot known as Operation Bojinka, which sought to blow up airliners over the Pacific Ocean).

As such, some of the intonations from officials about "mass murder on an unimaginable scale" strike me as hyperbole. Had the 9/11 bombers hit lower on the World Trade Center towers or hit a half-hour later, they could have likely killed thousands more people than the roughly 3,000 they actually did.

However, the fanatics behind these plots are not stupid people (although fortunately for us, they aren't criminal masterminds either). One of these times, they will get "lucky" -- and mass tragedy on a scale even greater than 9/11 will ensue.

The one I still fear is a dirty bomb or suitcase nuke detonated in a world financial capital.