Reading the newspapers, it might be possible to formulate a rough explanation of the term “populism.” It begins with the observation that the problems of the modern world are highly complicated, long-term, often inter-connected, and—in the eyes of some–materialist.
The highly complicated nature of problems means that they are best understood by experts, rather than by the common person. Examples include the federal judiciary, which regulates national law; the Federal Reserve Board, which broadly regulates the level of economic activity; and the Joint Chiefs of Staff, which represent the professional opinion of the United States military. The bench is full of lawyers, the Fed is full of economists, and the Joint Chiefs is full or warriors. None are elected; all are insulated from political pressures.
Many problems are not only complicated; they are also of long duration. In contrast, elected officials tend to have a two-year, four-year, or—at most—six-year existential time horizon. Climate change offers a good example of this effect. Faced with stiff resistance in the Senate, President Barack Obama sought to use executive agreements and Executive Branch rule-making to enshrine carbon reduction policies that reach out as far as 2050. Within a few years, President Donald Trump could just withdraw the United States from the Paris Climate Accords and tell his own cabinet Secretaries to start undoing the Obama rule-writing.
Inter-connections abound. To take only one example, climate change is likely to set off large-scale population movements across national borders. It’s likely to increase the frequency, size, and economic impact of both wildland fires and of cyclonic storms. It makes a case for an urgent transition away from carbon-burning without any sustainable replacement energy technology—except new generation nuclear reactors—offering a swift and scalable replacement.
American politics (but not only American politics) has been dominated for at least a century by the bi-partisan belief that, more than anything, voters want money so that they can buy stuff. During the Depression, the Roosevelt administration adopted a policy of “tax-spend-elect.” Using this policy, Democrats held the White House from 1932-1952, 1960-1968, 1976-1980, 1992-2000, and 2008-2016. Fed up with losing, Republican eventually adopted the policy of “tax cut-spend-elect.” It worked. Using this policy, Republicans went from winning the White House 45 percent of the time to winning it 60 percent of the time.
Insisting that complicated problems are best understood and managed by highly educated professionals dedicated to “public service” inevitably discounts the value and views of the common person. Voters can be easily distracted by controversies over things like transgender monuments and Confederate bathrooms, but elites can claim to govern in the common interest.
However, a long string of failures can undermine deference to elite guidance. So can non-materialist values or goals among common people. The result can be an upwelling of wrath on the part of at least some of the common people. This is what is labeled “populism.”
 Currently, none of these is in good repute, what with the excesses of judicial activism, failure to fend-off inflation, and the flunked wars. All have deep reservoirs of previous good conduct to help see them through choppy waters.