Progressivism originated in corporatism, not populism.

Writing on the origins of the Federal Reserve, Murray Rothbard discussed the philosophy which helped produce it and which still dominates our political discourse today:  progressivism.  It's not a commonly used word in modern politics, though it has of late become more popular as a self-descriptor on the left.  Nonetheless, progressivism is a philosophy of social democracy, based in the general will of Rousseau, which seeks to improve society -- to make it progress -- through government intervention and programs. 

Most examples of what is now called a "liberal" or a "leftist" is much more accurately termed a "progressive."  (The distinction is important, I promise.  Who hasn't been confused or confusing when trying to talk about classical liberalism with those who think of "liberals" as people who support overwhelming government intervention in the economy?  Call them progressives instead and your problem goes away.)  At any rate, Rothbard writes:

The Federal Reserve Act of December 23, 1913, was part and parcel of the wave of Progressive legislation on local, state, and federal levels of government that began about 1900. Progressivism was a bipartisan movement that, in the course of the first two decades of the 20th century, transformed the American economy and society from one of roughly laissez-faire to one of centralized statism.

The Costs of Carbon Legislation

We could have a dragon.

My friend, not exactly a libertarian but not a socialist (pro-market, anti-war, anti-cop) — okay, pretty libertarian, actually — thinks that if the US government, for the last 40 years, had spent nothing on war or welfare or anything else, but retained the same tax schedules, it would have been able to fund the creation of a dragon. Yes, a dragon.

The Upside-down World of John Maynard Keynes

John Maynard Keynes often employed flowery language like "animal spirits" and "liquidity trap" to describe things he did not understand. He was, after all, more of a bureaucrat than an economist. In fact, he would best be described as an anti-economist because he eschewed things like supply and demand and held the opinion that government could run the economy. So, for example, he could not understand why people would invest resources in risky adventures that helped keep the economy growing at full employment. He therefore substituted "animal spirits" for the profit motive. These spirits allow entrepreneurs to proceed with a naïve confidence and to set aside concerns over losses. Similarly, the failure to invest was also a psychological problem that he dubbed the "liquidity trap." This trap occurs when investors seek liquidity in cash and when monetary policy — in terms of cutting interest rates — no longer produces an increase in investment.