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Bernie Sanders’s core problem is selling his “revolution” as a plausible political approach.

The great sociologist Max Weber distinguished between two types of politics, one based on an “ethics of conviction” (which deals with ultimate goals) and one based on a “ethics of responsibility” (which deals with what is political achievable). In the grand battle between Sanders and Hillary Clinton, we see these two styles of politics in contention. With his promise of “political revolution,” Sanders is offering a politics of conviction of a sort that we haven’t seen since George McGovern and Barry Goldwater. Clinton is countering with a reminder of what is possible in the American system. Her critique of Sanders’s approach to health care is all about the fact that it would be so difficult to do, given that it took decades of work to get to Obamacare. 

The flip-side of the excitement Sanders is generating is that he needs to convince voters that his “political revolution” can work. And here is the great difficulty, because the American system (which Hillary knows from the inside as well as anyone alive) is structured to resist systematic change. As Jamelle Bouie rightly noted in Slate: “But he’s also a politician, subject to the same forces as his peers, and neither he nor his allies can ignore the structural realities of American politics.”