One of the nice things about being a human being is that when you have a problem, you can appeal for help, and you'll often get it. People actually want to help people. (Unlike chimps, who have a very nasty attitude.)

You would not believe how many people called my office after the earthquake in Haiti on Jan. 12, 2010, and asked how they could help. A lot of those people had never met a Haitian in their entire lives. But they wanted to help.

I'll give you another example.

I went to Somalia a few years ago. I went with a group. Our group also visited other countries in East Africa. We flew from one country to another, often because land borders were closed. But flights were few and far between.

Upon arrival at the airport in one small country, the immigration official noticed that the visa for a member of our group had expired. She said that that member would have to re-board the flight, and return from whence we had come. Which was a huge problem, because the next flight was four days later, and we were staying only for three.

In some parts of the world, such problems are solved by the sudden appearance of cash. Sure enough, cash suddenly appeared.

The immigration official quietly declined the offer. She reiterated that our colleague needed to re-board the airplane. This caused a great deal of consternation within our group.

Our group leader was possibly the most traveled human being who ever lived. For instance, he had been to Ethiopia, a nearby country, more than thirty times. He knew a thing or two about human nature. He went up to the immigration official, he quietly and tactfully explained the awful consequences for our colleague if he were separated from our group, and he then used the magic words:

"Have a heart."

He said those words three times.

The immigration official smiled (for the first time), took the passport with the expired visa, and told him that everyone would have to wait until she returned. So we did.

The plane left. We didn't know whether that was a good thing or a bad thing.

After 45 minutes, she came back. She showed my colleague that inside the passport there was a new, valid visa.

"No charge," she said in French.

What makes a $15 minimum wage politically possible? It's because people have a heart. Why immigration reform? Because people have a heart. Why universal healthcare, paid sick leave, free public college? Because ... people have a heart.

Our progressive campaign is not rooted merely in idealism, the conviction that the world can be a better place. Our progressivism is rooted in human nature, that shared spark in all of us we call "empathy." In a very fundamental way, we care about each other. We love each other. We want everyone to live a decent life - even people we've never met, and never will meet.

We all have a heart.