In advance of President Obama's State of the Union address tonight, we conclude our series framing the issues that face the nation.

One year ago, after the shooting and wounding of Arizona Rep. Gabrielle Giffords, many members of Congress put aside their petty animosities -- as well as deeply held philosophical differences -- and sat together for the president’s State of the Union address. Democrats with Republicans, liberals with conservatives.

For the plurality of Americans with independent leanings and moderate impulses, it was a nice gesture. It was also temporal, as was the bipartisan singing of “America the Beautiful” on the steps of the U.S. Capitol steps after the attacks of 9/11.

The level of civility in Washington "is a reflection of what’s going on in the rest of the country that seems to be entertained by reality television programs,” says Diana Banister, a public relations veteran who has worked for several Republican candidates, including Bob Dole. “These shows -- ‘Jersey Shore,’ ‘Real Housewives of Wherever,’ et cetera -- show women and men calling each other names, backstabbing, gossiping and pretty much doing whatever it takes to get ahead or win the guy. The culture is awash in incivility; why would politics be any different?”

But there are reasons across-the-aisle cooperation is needed in American politics, ranging from the advantageousness of a cohesive U.S. foreign policy to the fact that real solutions to the nation’s most intractable problems -- massive federal debt, entitlement reform, health care legislation -- truly take root when both major parties are invested in them.

There are also many reasons why across-the-aisle cooperation in Washington has become so rare. These range from gerrymandered congressional districts, ideologically polarized political parties, the flood of unregulated special interest money into campaigns, the exigencies of base politics, the tactics of political consultants, and the splintering of the media, which has both coarsened political discourse and contributed to increasingly self-segregated audiences.

When it comes to what newspapers and magazines Americans read, what television and radio stations they listen to, what websites and blogs they patronize, and which social media groups they belong to, today’s citizenry is all about reinforcing their own views -- and demonizing those of their opponents. The Internet is often blamed for this trend, but the impetus behind these changes predate social media, the World Wide Web, or even cable television.

Opening up the political process in the 1960s and 1970s produced -- from both the left and the right -- a new ethos: The personal is the political. Everyone from feminists, gay rights activists, evangelical conservatives, and muckraking journalists embraced it. The result? Greater accountability of elected officials, perhaps, and the exposure of hypocrisy. But also: impeachment proceedings against a popular president, and savage news coverage of a vice presidential candidate who came from far outside the power corridors of Washington.

As it turns out, personalizing the nature of policy questions leads naturally to character assassination. This impulse now reinforces itself on platforms such as Twitter and Facebook -- and in the comments sections of the most neutral of news outlets.

The United States of America has always hosted robust political discourse, bare-knuckles election campaigns, and free-wheeling public debates. They can be enlightening, even fun. The question is whether we’ve indulged ourselves so much in name-calling and condemnation that when it’s time to cooperate, negotiate, or legislate, no one knows how anymore.

In the summer of 2010, when Sen. Mitch McConnell told National Journal’s Major Garrett that the Republicans strategy is to ensure that Barack Obama is a one-term president, White House aides figured, “Why bother negotiating with this guy?”

For their part, Republicans concluded something similar about Obama in the first week after his inauguration. On Jan. 27, 2009, Obama visited Republicans on Capitol Hill ostensibly asking for their ideas on the stimulus, while votes were already being cast for this legislation on the House floor.