'The Moral Arc:' What's behind the world's good behavior?

History is filled with horrific acts, from centuries of slavery to mass genocide to the spectacle of public executions. People once filled the public square to watch heads roll.

Though such atrocities still occur in the modern age, the scale has decreased dramatically. What explains this shift? Has the world become more moral? And if so, how?

In "The Moral Arc," Michael Shermer tackles this question with the idea of scientific reasoning. He argues that the rise of "scientific rationalism" has created a more aware and informed population, which is in turn less prone to violence.

The power to reason and to compare has effectively re-calibrated the world's moral compass.

Shermer joined MPR News' Kerri Miller to discuss his book and how it applies to modern conflicts.