In his bestseller "The Better Angels of Our Nature," Harvard psychology professor Steven Pinker described the decline of violence in the world. In his new book, "Enlightenment Now: The Case for Reason, Science, Humanism and Progress," Pinker builds a persuasive case that life is getting better across a host of measures. Emma Seppala, science director of Stanford University's Center for Compassion and Altruism Research and Education interviews Pinker below.

Q: Looking at the news, we often think things are getting worse and worse. However, in your book, you make the powerful and deeply researched argument that things are actually getting better. Can you please explain this conundrum?

Pinker: Think about it: If you arrived in a new city and saw that it was raining, would you conclude, "The rain has gotten worse"? How could you tell, unless you knew how much it had rained before that day? Yet people read about a war or terrorist attack this morning and conclude that violence is increasing, which is just as illogical. In fact, rates of war have been roller-coastering downward since 1946, rates of American homicide have plunged since 1992, and rates of disease, starvation, extreme poverty, illiteracy and dictatorship, when they are measured by a constant yardstick, have all decreased — not to zero, but by a lot.

Q: But even if civilization is improving from a birds-eye view over the long-term, things can get still worse for many years in the short-term, right?

A: Progress is not the same as magic. There are always blips and setbacks, and sometimes horrific lurches, like the Spanish flu pandemic, World War II and the post-1960s crime boom. Progress takes place when the setbacks are fewer, less severe or stop altogether. Clearly we have to be mindful of the worst possible setback, namely nuclear war, and of the risk of permanent reversals, such as the worst-case climate change scenarios. ... Of course life is bad for those people with the worst possible lives, and that will be true until the rates of war, crime, disease and poverty are exactly zero. The point is that there are far fewer people living in nightmares of war and disease.

Q: Is this optimistic outlook primarily U.S.-centric or does it vary dramatically depending on the part of the world?

A: The progress is not particularly American — indeed, the United States is an outlier among rich Western democracies, with a stagnation in happiness and higher rates of homicide, incarceration, abortion, sexually transmitted disease, child mortality, obesity, educational mediocrity and premature death.

The countries with the highest levels of well-being are in Western Europe and the [British] Commonwealth, and the countries with the most dramatic improvements in well-being are in the developing world, which are slashing their rates of poverty, hunger, disease and illiteracy. And while inequality is increasing in the United States, it's decreasing in the world as a whole, because poor countries are getting richer faster than rich countries are getting richer.

Q: You argue the reason for this positive trend is certain ideas and values are driving this improvement. What do you think are the most important ideas and values we should pass on to our children to continue to uplift human civilization?

A: The main idea is a belief in progress — not a faith that it will happen by itself, but a realization that when people strove to improve the human condition in the past, they gradually succeeded. They came up with democracy, and vaccines, and hybrid crops, and the rule of law, and a free press, and much else. And they did it because they held certain values. They valued reason: The conviction that logic and evidence are better than authority, charisma, gut feelings or mysticism. They valued science: The idea that we can understand the world by proposing explanations and testing them against reality. And they valued humanism: The idea that the well-being of men, women and children is more important than the glory of the tribe, race or nation.

Q: Although you argue against extreme political and religious views, many of the humanistic values you extol have for centuries been promoted by spiritual and philosophical traditions. Are you arguing for a secular society?

A: Yes, I believe in the First Amendment prohibition of an established religion, and any other attempt to make collective decisions based on parochial dogmas rather than universally agreed-upon reasons. But many religions themselves have evolved to incorporate the lessons of the Enlightenment, and have de-emphasized supernatural beliefs and Iron Age morality in favor of our best understanding of reality and the ideal of universal human flourishing.

Q: How can we best capitalize on the positive cycle we are in to ensure things keep improving for our society and the human race?

A: First, we should stop seeing every unsolved problem as the symptom of a sick society, as if we had the right to a perfectly affluent and harmonious world, and any shortcoming the work of evil saboteurs. Until the messiah comes, problems are inevitable; they come with living in an indifferent universe. We should appreciate the precious institutions like liberal democracy, science, markets, the rule of law and international organizations, that have made life so much safer, healthier and more peaceful than it was in the past. We should seek to apply reason and open-minded hypothesis testing to solving the problems that remain, rather than appealing to the dogmas of our political tribes, or undermining the institutions in the hope that nothing could be worse than the flawed status quo. We know many things that are worse: Nazi Germany, Maoist China, current-day Venezuela, to take a few examples.

Q: How has your understanding of the improvement of the human lot impacted you, your behavior, choices and ideas?

A: It's made me far more engaged — in politics, in charity, in advocating for positive change. Before learning how life had improved, I was more fatalistic: Resigned to violent conflict, pessimistic about poverty, jaded about both government and civil-society activism. I now see hopes for human improvement as not just uplifting but practicable.