Harvard Johnstone Family Professor of Psychology Steven Pinker appeared on "The Colbert Report" this past Tuesday to showcase his new book, "The Better Angels of Our Nature: Why Violence Has Declined."

Stephen Colbert started with a question concerning the book's subtitle, asking, "What do you mean violence has declined? There's violence everyday; turn on 'Real Housewives.'"

Pinker responded that violence per capita has been in decline over the past several thousand years. "We may be living in the most peaceful era of our species' existence," Pinker said.

Pinker primarily focused on the dramatic decrease in violent warfare since the World Wars. "If you plot the rate of death in warfare, since World War II, it's a bumpy downhill decline," he said.

Pinker also cited a similar decrease in homicides over the past few centuries, saying, "In the middle ages you were 35 times more likely to be murdered than you are today."

Pinker's book, which came out earlier this year, refutes the notion that we live in a particularly cruel period of human history. Pinker acknowledges that violence is still a prevalent issue, but he argues that human proclivity toward violence has conspicuously diminished.

Pinker has appeared on "The Colbert Report" twice before: first in 2007 and then again in 2009 to present one of his earlier books, "The Stuff of Thought: Language as a Window Into Human Nature." This upcoming spring semester Pinker will be teaching Science of Living Systems 20: "Psychological Science."

The full interview is available here.

This post has been revised to reflect the following correction:


An earlier version of the Oct. 23 post "Back for a Third Time: Steven Pinker on 'The Colbert Report'" included a quote from Colbert in which he misidentified the source of the title of Pinker's book. It is, in fact, derived from Lincoln's first inaugural address.