Jay Cost of National Review Online sees a rise in radicalism within our major left-of-center political party.

[B]efore Democrats embrace socialism, they would do well to ponder just what a break from the party’s history the Sanders/Ocasio-Cortez faction is proposing. For roughly 70 years, the Democratic party has successfully kept radical forces at bay and, as a consequence, enjoyed political success.

Post-war liberalism, far from being a radical political program, actually had the effect of isolating and minimizing left-wing radicalism in the United States. One could argue that this was liberals’ intent — on both the domestic and the international fronts.

Domestically speaking, the essence of post-war liberalism was to share the bounty of capitalism in a more egalitarian manner. …

… Put aside the merits of this agenda — whether it has been successful on its own terms, or whether it has produced bad side effects (I am in the latter camp). The point is that this is how the mainstream Left viewed its own project. And in at least one important regard, the agenda was enormously successful: It mostly pushed the radical fringe outside politics.

We’ve mainly forgotten the 75 years between the Civil War and the Great Depression, and when we do remember them, we think of the era as one of corrupt contentment. But there was a radical undercurrent to the politics of the period; at times, it threatened to drag the whole nation down with it.