Are Democratic advocates for single-payer health care the mirror image of repeal-and-replace Republicans, substituting a feel-good slogan for actual policy development?

Probably not.

It’s tempting to believe that’s a likely outcome of Bernie Sanders’s crusade for single-payer, which is picking up momentum within the party despite the fact that Sanders seems mostly indifferent to the details of the issue. But I think it’s a big mistake to equate Sanders with repeal-and-oh-we’ll-figure-it-out-later Republicans.

For one thing, the general disgust practically everyone seems to have with Republican politicians over health care probably confuses the issue a bit.

What’s wrong with what Republicans have done is that they made “repeal and replace” their top priority both in campaigning and in governing, and yet almost none of them actually did the work to figure out how to overhaul the nation’s health care system — and almost none of them seemed to even notice that was going on or considered it a problem.

That doesn’t mean, however, that all politicians have to be serious policy wonks for the political system to work. There’s nothing wrong with having a variety of roles in a party — some rabble-rousers, some sloganeers, some politicians who are a lot better at inspiring than at the nuts and bolts of legislating. There’s nothing wrong with messaging bills no one would want to vote for if they were actually going to become law.

In a normal party, however, a bunch of things happen. One is that there’s a more or less natural division of labor, in which — along with those other types — there are some serious legislators. Another, however, is perhaps even more basic In a normal party, party actors (interest groups, activists, etc.) mobilize and attempt to push their version of whatever policy has moved to the top of the agenda.

For whatever reason, that process appears to have broken down in the current Republican Party, but not within the Democratic Party. So I fully expect that in the run-up to the 2018 and 2020 elections, as long as the undefined “single payer” seems important to many Democrats, various party actors will attempt to define “single payer” according to their own preferences.

And the same has been and will continue to be true for climate, and taxes, and income inequality, and whatever else rises to the top of the party’s agenda. And the result will be that by the time Democrats are elected (whenever that happens), they will be committed to something far more specific than what they are talking about now.

Again, that’s not because Democrats are all noble wonks and Republicans are all demagogues, and certainly not because liberals are inherently focused on details while conservatives are not. The difference has to do with the incentives in the parties as they are currently organized.

And while it’s possible that Democrats could become as dysfunctional as Republicans, the fact that some Democratic politicians don’t pay much attention to policy details isn’t really evidence they are moving in that direction.

Jonathan Bernstein is a Bloomberg View columnist. He taught political science at the University of Texas at San Antonio and DePauw University and wrote A Plain Blog About Politics. Readers may email him at jbernstein62@bloomberg.net.