Alice Rivlin , a longtime scholar at the Brookings Institution think tank, enjoyed an unusually constructive career.

Over more than four decades, Rivlin — who died in May at age 88 — served as the first director of the Congressional Budget Office, the deputy director and then director of the Office of Management and Budget and the vice chair of the Federal Reserve Board. She authored many reports and was deeply engaged in the problems of the District. To some in this town, she was known affectionately as “the queen of Washington’s budget wonks.”

But there is more to her passing than being a pioneer for women in public service and economics. (She was president of the American Economic Association in 1986.) I mean no disrespect when I say Rivlin has also personified what I and others have called “policy entrepreneurs.” They were to be society’s fix-it specialists, repairing its defects and leaving a better tomorrow than today.

Just as economic entrepreneurs create and sell new products or services, policy entrepreneurs could create and sell new policies. The process was straightforward.

First, the public must be made aware that there is a problem that harms the national interest. This occurs through symposia, scholarly studies, reports, congressional hearings, sympathetic newspaper articles, television coverage and blogs that publicize the problem — whether it’s climate change, homelessness, high taxes or whatever. Liberals, conservatives, Republicans and Democrats could all adopt a similar approach.

Next, some solution must be found that would eliminate or mitigate the problem. If the problem can’t be diminished, then making people aware of it is a guaranteed exercise in frustration. Pundits and columnists such as me enlist in the cause, pointing out what’s right or wrong with the status quo and what can be done about it. When I said that I meant no disrespect to Rivlin, one reason must be obvious. I am a collaborator in the same process, advocating ideas that I favor and criticizing ones that I don’t.

Great hopes were invested in this process. The nation’s intellectual firepower was being directed for the greater good. Or so it was thought. The reality was different. The larger symbolism of Rivlin’s death is that it signifies the failure of this vision to meet expectations. The United States still has plenty of poverty; racial tensions endure; the immigration system is a mess. There are deep divisions as to what we should do. And so on.

The post-World War II generations of policy entrepreneurs endured a lifetime of frustration. In a large sense, Rivlin’s life and death experience is a metaphor for this failure.

It might seem that the policy entrepreneurship that I describe is simply politics as it has always existed. There is some truth to this — but less than you might think. Before World War II, most national politics involved conflicts among interest groups (businesses, farmers, workers, regions). These still exist.

But they have been overshadowed by new idea groups and think tanks. By one estimate, there are now 1,830 think tanks in the United States, and the number has roughly doubled since 1980. About a quarter of U.S. think tanks are located in Washington, according to a report by the Institute for China-America Studies.

We have created a new class of policy entrepreneurs whose power, prominence, status and influence depend on their presumed superior understanding of “the issues.” The result is political congestion, with all manner of problems competing for the public’s limited attention span.

The new political system often is helpless and immobilized. What happened? Why was this new political elite unable to prepare us for the future? I can think of at least three plausible explanations:

1. It might be that the problems they attacked were tougher than expected. Eliminating poverty, combating climate change and controlling health costs are hard tasks individually, let alone together.

2. Elected politicians, who wielded the real power, found many of these ideas too unpopular. Take climate change. Almost everyone outside the Trump administration (it seems) is against it; but there’s little enthusiasm for the actual policies — higher fossil fuel prices or energy controls — that might have some effect.

3. The policy entrepreneurs might have discovered that they aren’t as smart as they thought they were. Put differently, they may have exaggerated their understanding of the things they were trying to change.

Whatever the cause or causes, the historical reality is unforgiving. Policy entrepreneurship hasn’t and won’t disappear. But the hoped-for gains have been conspicuous by their absence. There is an enduring cycle of disappointment. Solutions are rarely equal to problems. It is a sobering legacy.

Read more from Robert Samuelson’s archive.

Read more:

Robert J. Samuelson: We are in the twilight years of the post-WWII baby boom

Colbert I. King: I used to think America would age out of racism. What was I thinking?

The Post’s View: Congress’s public policy problem from hell

Catherine Rampell: Stephen Moore wants people to pay more attention to his economic policies. Challenge accepted.

Alexandra Petri: I wish we would talk more about Policy (just not Elizabeth Warren’s)