I first became a vegetarian when I was nine, in response to an argument made by a radical babysitter. My great change - which lasted a couple of weeks - was based on the very simple instinct that it's wrong to kill animals for food.

Despite the fact that in America we incarcerate more juveniles for life terms than in any other country in the world, the truth is that the vast majority of youth offenders will one day be released. The question is simple and stark. Do we want to help them change or do we want to help them become even more violent and dangerous?

There is at least one point in the history of any company when you have to change dramatically to rise to the next level of performance. Miss that moment - and you start to decline.

In one century, we've added 28 years to our average life span - a change so rapid that our brains couldn't possibly have evolved to accommodate it.

My point is that perceptual bias can affect nut jobs and scientists alike. If we hold too rigidly to what we think we know, we ignore or avoid evidence of anything that might change our mind.