Beginning Sunday evening with the holiday of Rosh Hashanah that marks the Jewish New Year, and continuing through Yom Kippur the following week, the world’s Jews engage in a period of self-examination.

As is often the case with Jewish ideas, this particular concept is refreshingly countercultural, especially in election season. As one rabbi recently pointed out to me, in election years in particular, we Americans are expert at detecting evil in other people.

Republicans and Donald Trump supporters have a long list of culprits to blame for problems: Illegal immigrants. President Obama. The liberal “mainstream media.” Radical Islam. The Washington establishment, “special interests,” and the “donor class.” Tenured college professors. Unionized public school teachers. Chinese currency manipulators. George Soros. Sidney Blumenthal. Government bureaucrats. Cop-killers. Welfare sponges. Some of these are genuine problems.

Democrats and Hillary Clinton have their own list of enemies. The pharmaceutical companies. Wall Street banks. The gun lobby. Donald Trump and his basket of deplorable supporters. Trigger-happy racist police officers. The fossil fuel industry. The Koch brothers. “The One Percent.” Roger Ailes. Vladimir Putin. Some, if certainly not all, of these are genuine problems, too.

What’s different about the Days of Awe, or the Ten Days of Repentance, as this period in the Hebrew calendar is known, is that rather than obsessing about other people’s sins — what a hateful liar Donald Trump is, or what a communist ISIS sympathizer Barack Obama is — Jews on these holidays are supposed to focus on our own sins.

Some of the work is communal — synagogues draw the largest crowds of the year, and families and friends gather together for meals — but some of it is individual, too. I’m supposed to sit around thinking not about how those despicable Democrats could be better, or how those repugnant Republicans could be better, but on how I can do better.

In other words, for ten days, rather than complaining about how Hillary Clinton is fundamentally dishonest or about how Donald Trump is an incorrigible liar, I can focus on contemplating how I can be more truthful. Instead of blaming other people for my own problems or the country’s, I can think about where I’ve fallen short and how I can improve.

Imagine how much healthier our politics and our country would be if some of this spirit of self-examination were exported from the Jewish religion into the rest of the American culture, if every time we rushed to vilify or scapegoat our opponents we paused to turn a critical eye on ourselves. That’s not to imply a moral equivalence between America and ISIS, or to deprive anyone of a justified opportunity to feel superior or to name a problem that needs fixing.

Too often in our public discourse, though, self-awareness is just a rhetorical device. It’s a nod in the direction of humility, rather than actual humility. I know I’m not perfect myself, but we’ve never seen anything like my opponent. Or: I’ve made mistakes, but now it’s time for all of us to move on.

What might change for the better in our country if just ten percent of the effort devoted to blame-casting and scapegoating were instead redirected to self-examination and problem solving? I’ll think about whether I’m being unrealistically naïve here. But you also may want to think about you’re being unduly cynical in dismissing the idea, if that is what you are doing.

In some ways, self-examination is challenging. It’s easier to blame Donald Trump or illegal immigrants or Barack Obama for America’s problems than for us each to ask ourselves how we may have fallen short. But if the Rosh Hashanah approach involves confronting some inner failings we might prefer to deny or avoid, it also is a hopeful way of looking at things.

Most of us, after all, have a lot more control over our own behavior than we do over Donald Trump’s or Hillary Clinton’s or whatever other external actor or actress we want to blame. Might as well start with the problems we have some chance of fixing.

Mr. Stoll is editor of FutureOfCapitalism.com.