We are now leaving the era of Self. The right and left now offer two different magnetic ideas. The Trumpian right offers Tribe. “Our” kind of people are under threat from “their” kind of people. We need to erect walls, build barriers and fight. The earlier American nationalism was about frontier; this is about the fortress. Tribalism is a magnetic idea that has mobilized people from time immemorial.

The left offers the idea of Social Justice. The left tells stories of oppression. The story of America is the story of class, racial and gender oppression. The mission now is to rise up and destroy the systems of oppression. This, too, is an electric idea.

The problem with today’s left-wing and right-wing ideas is that they are both based on a scarcity mind-set. They are based upon us/them, friend/enemy, politics is war, life is conflict.

They are both based on the fantasy that the other half of America can be conquered, and when it disappears we can get everything we want. They are both based on the idea that if we can just concentrate enough power in the centralized authoritarian state, then we can ram through the changes we seek.

So a lot of us reject these two ideas. A lot of us don’t want to live in a war society, whether it’s a tribal war or a class war. If the 2020 choice is between Donald Trump and a Democrat who supports the Green New Deal, I’d vote for any moderate alternative.

It doesn’t have to be that way.

What is the core problem facing America today? It is division: The growing gaps between rich and poor, rural and urban, educated and less educated, black and white, left and right.

What big idea counteracts division, fragmentation, alienation? It is found in Leviticus and Matthew: Love your neighbor. Today’s left and right are fueled by anger and seek conflict. The big idea for moderates should be solidarity, fraternity, conversation across difference. A moderate agenda should magnify our affections for one another.

There are four affections that bind our society, and moderates could champion a policy agenda for each:

We are bound together by our love of our children. The first mission is to promote policies to make sure children are enmeshed in webs of warm relationships: child tax credits, early childhood education, parental leave, schools that emphasize social and emotional learning.

We are bound to society by our work. The second mission is to help people find vocations through which they can serve the community: wage subsidies, apprenticeship tracks, subsidies to help people move to opportunity, work councils, which are clubs that would offer workers lifelong training and representation.

We are bound together by our affection for our place. The third mission is to devolve power out of Washington to the local level. Out-radicalize the left and right by offering a different system of power, a system in which power is wielded by neighbors, who know their local context and trust one another. Create a national service program so that young people are paid to serve organizations in their community.

We are bound together by our shared humanity. The fourth mission is to embrace an immigration policy that balances welcome with cultural integration. It’s to champion housing and education policies that encourage racial integration. Neither left nor right talks much about racial integration anymore. But it is the prerequisite for national unity.

Let the left and right stand for endless political war. The moderate seeks the beloved community. That, too, is a magnetic idea.

David Brooks has been a columnist with The Times since 2003. He is the author of “The Road to Character” and the forthcoming book, “The Second Mountain.”