Indeed, I think we could learn a lot not just about prisons from Scandinavian countries, but also on how to prevent crime in the first place by seriously combating poverty.

FORBES: Are Norwegian Prisons Too Soft?

There is so much more we need to learn about how to prevent violence, but we could start with the sex difference that is staring us in the face.

CNN: The overwhelming maleness of mass homicide

Not only will completion of the financial regulatory reform bill provide some certainty to the markets about how we are going to prevent a crisis like this from happening again, but it also ensures that consumers are going to be protected like never before on all the things day to day that involve interactions with the financial system.

WHITEHOUSE: President Obama on the Economy & Financial Reform

But we know what can cause mine explosions, and we know how to prevent them.

WHITEHOUSE: President Obama Orders Review of Mine Safety

This is how we prevent most (but sadly not all) frivolous cases from ever making it to court.

FORBES: The British Government Has Decided To Censor The Entire World's Press And Media

Low-dose aspirin is already recommended to cut the risk of heart attack and stroke, but there are no national guidelines on who should consider taking it to prevent cancer, or how much to take.

BBC: Aspirin a 'no brainer' against cancer after screening

In 2008, the AAP revised its guidelines, citing little evidence that such delays prevent the development of food allergies, but it didn't say when and how to introduce such foods.

WSJ: Food Allergy Advice for Parents: Start Peanuts, Eggs and More Sooner

We now know how to prevent heart attacks, and how to help patients survive when they have them, but it helps to be an informed consumer.

FORBES: Clinical Trial Advice For Investors From Two Pros

Not only did that prevent the repeat of a failure, but it sometimes led to valuable insights on, say, how to make a manufacturing process more efficient.

FORBES: Magazine Article