When the partisanship get in the way of toxic bipartisan "compromises," it is a good thing. But partisanship can still be very damaging, particularly when it trumps policy.
For one, partisan identity can override policy preferences in voting behavior. Political scientist Lilliana Mason had an article in the Washington Post on Friday to discuss this. Why did a number of red states that voted for liberal policies or against conservative ones also vote for Republicans--and by large margins? Part of it lies in how partisan identity works. She explains,
My research suggests a key reason why this happened: our partisan identities motivate us far more powerfully than our views about issues. Although voters may insist in the importance of their values and ideologies, they actually care less about policy and more that their team wins.
This “team spirit” is increasingly powerful because our party identities line up with other powerful identities, such as religion and race. Over the last few decades, Republicans have generally grown increasingly white and churchgoing, while Democrats have become more non-white and secular. This sorting of identities makes us care even more about winning, and less about what our government actually gets done.Her paper Smells Like Team Spirit: How Partisan Sorting and Identity Polarize Political Behavior" is available in full online, and I recommend reading it.
When social and partisan identities align, we begin to detach our votes for candidates from our policy interests. The most important thing is to stick with the team. It doesn’t matter if the team you voted for opposes the very policy you voted to enact.
Partisan identities can abstract people from policy debates. They can also shape how partisans view policies. In his article "Party over Policy: The Dominating Impact of Group Influence on Political Beliefs," political scientist Geoffrey Cohen showed how liberals would support stringent welfare policies if told that Democrats supported them and that Republicans would support generous welfare policies if told that Republicans supported them. The effect of party reference group overrode substantive content for both groups.
We see this dynamic frequently today, as Republican will show support for environmental regulations in polls--that is, until Obama's name enters the picture. And we see how the change in White House influences attitudes toward mass surveillance. Republicans who once supported it now oppose it. Democrats who once opposed it are ambivalent are outright supportive.
A similarly dangerous aspect of this impact of partisanship over policy preferences is how it leads many Democrats to assume that Democratic politicians are doing the right thing. It becomes easier to ignore the closeness of the administration to Wall Street or how Obama killed ozone and child labor regulations. Partisan influence will not mean that Democratic voters will suddenly support gutting environmental regulations or labor regulations to appease business, but the divergence between the presumption of ideological affinity and the reality of policy might not fully register for people. Given how weak policy-related reporting is in the first place, it's very easy to trust the "team" and get on with other things. But no team should be left unquestioned.