Forty years ago I spent the weeks between final exams and my Yale Commencement in Israel on an Arab-Jewish relations project. That country had recently won the Six-Day War and seemed morally and physically indestructible. But Yale had taught me to look for undersides, and I went to find them and help if I could.

As a graduating senior I, too, seemed morally and physically indestructible. So did New Haven, which always gets lovely just when you’re leaving. Here, too, appearances had undersides, and Yale would help me to face them.

Just after my last final exam, two friends and I stayed up all night and decided to go for a bike ride at dawn. We didn’t own bikes, but the Old Campus and residential college gates were unlocked then, as were most students’ un-fancy wheels. We borrowed some and pumped our way up Prospect Street and over to East Rock in a pearly dawn, ending at a Chapel Street diner before returning the bikes to their racks and ourselves to our Davenport beds.

We didn’t see any undersides then. Commencement season isn’t the time to see them. Yet Yale’s campus gates are locked now, as are Israel’s, in ways we’d never have expected. Here in America some speak of a criminal “underclass.” Others say it mirrors a criminal, dysfunctional over-class. Some take it all as inevitable and tell us to toughen up and take harder measures, especially below.

They’re half right: Some years out of Yale, I worked in inner-city Brooklyn and watched Rudy Giuliani force New York, that capital of liberal “root cause” explanations for every social problem, to get real about tough remedies that restore enough order for freedom to regenerate itself.

But I soon learned that such advances had undersides, riding on swift currents of wealth and power that weaken what they claim to defend.

The “toughen up” crowd thinks that the New Haven of my bike ride and the Israel where I roamed freely and conversed with Arabs are utopian fantasies, not realities I’ve actually lived and lost. Yet their War on Terror only produces more terrorists, and the fivefold spike in America’s prison population since 1969 brings no peace as the market riptides it rides push force and fraud up the social scale.

As a political science major here, I learned from James Patrick Sewell, Isaac Kramnick and a visiting Wilson Carey McWilliams, and from roommates and friends, that a good society, like a healthy person, strides on two feet: Without the “left foot” of social provision and education, conservatives’ cherished virtues can’t flourish. Without the “right foot” of personal responsibility and autonomy, liberal social engineering can reduce persons to clients, cogs or worse.

Yale College at its best teaches a civic-republican balance of left and right, of humanist truth-seeking and republican power sharing. It shows its students how to assert authority — and how to reduce the need to assert it. “The presumption of innocence is not just a legal concept. In commonplace terms it rests on that generosity of spirit which assumes the best, not the worst, of the stranger,” wrote Kingman Brewster Jr., Yale’s president in my time.

One can “assume the best” naively. Or one can come up with the personal, political and professional courage to assume it wisely. Yale teaches the public art of extending trust wisely enough to elicit it in return, as Brewster did.

Giuliani never got that balance right. George W. Bush ’68 finessed it but couldn’t deliver it. But many Americans learn it in civic cultures and centers that Yale graduates seed, lead and support.

This semester, the Yale course “Classics of Political Journalism,” taught by Mark Oppenheimer, read “The Closest of Strangers,” a book I wrote about obstacles to extending trust in 1980s New York. As I was gestating that book during my inner-city years, I got a call one night from a Yale classmate, a banker seeking my gift to the class fund.

I told him I was earning too little to contribute. (I didn’t tell him that I was deeply, darkly happy and that Yale seemed a million miles away.) “I think I understand,” he said, “and I respect what you’re doing.” I realized then that Yale wasn’t so far away; its tradition of balancing humanist truth-seeking and republican power-sharing was in me.

That tradition became morally and physically indestructible again the night of Nov. 4, as students poured into Old Campus. To my amazement, many sang “The Star Spangled Banner” spontaneously, reclaiming civic-republican patriotism from lapel-flag-pin poseurs, but reaching for them, too, with the anthem itself.

They did it a few yards from where I’d borrowed that bike in the trusting dawn of my 1969 commencement. They did it standing on both feet.

Jim Sleeper is a lecturer in political science and 1969 graduate of Yale College.