Why? That’s what we examine in a recently published paper in the British Journal of Political Science. Many observers have noted that Americans are more likely to take the side of their party on the issues of the day in the last 30 years. But the Republicans are more unified — and as a result, more powerful.

Although both Democrats and Republicans are more ideologically consistent and committed than they were 40 years ago, Republicans are far more so than Democrats. The overwhelming majority are conservative not only in name but all the way down. This means identifying with one’s party’s political outlook, knowing how the main parties’ ideological positions relate, and being attached to one’s party’s ideological and policy concerns. Thanks to that greater consistency and commitment, Republicans can resist pressure to move society in a more liberal direction.

AD

AD

The result: though the Republican Party is the smaller party, it can punch above its weight.

For as long as political science has had data on this, Republicans have been:

Twice as likely as Democrats to support their party’s ideological policies.

50 percent more likely to know that the Republican Party is more conservative than the Democratic Party.

More than twice as likely to have ideological reasons for supporting their party.

More than four times less likely to list social reasons for identifying with their party.

These differences aren’t because of demographic differences like income, education, race or ethnicity. It’s not because of differences in political knowledge. Even those self-identified Republicans who, according to American National Election Studies interviewers, weren’t well-informed about politics knew more about the ideological structure of U.S. politics than self-identified Democrats who were very well-informed.

This ideological sophistication keeps Republicans from being attracted to popular social welfare policies. Below, using data from the 2012 American National Election Study, we show mean support for a number of social welfare policies among Democrats (columns 1 and 2) and Republicans (columns 3 and 4) who are more and less ideologically sophisticated.

As you can see, Democrats don’t need to be ideologically aware — i.e., to know what’s “liberal” and what’s “conservative” — to want to increase government support for social security, public schools, child care and the like.

AD

AD

But adopting conservative ideology deeply affects Republicans. Far more than Democrats, Republicans who are and who are not well-versed in ideology have very different opinions on social welfare programs. In fact, in many instances, Republicans who aren’t very ideological hold positions — for example, on Social Security and public schools — that are more like those of Democrats than like those of highly ideological Republicans.

Meanwhile, those Republicans who are steeped in conservative ideology resist increased spending for the most popular social policies, like Social Security and public schools. In fact, they decisively support cutting government spending on other policies that are nearly as popular, like unemployment, health care, child care and antipoverty programs.

For Republicans, the mean difference in policy positions between the groups was four times larger than for their Democratic counterparts.

Ideological sophistication also inoculates Republicans from taking positions that someone might consider liberal. In one experiment we conducted, we asked 2,015 respondents, who had already identified themselves as either Democrats or Republicans, to rank their support for increased funding for food stamps, i.e., government-issued coupons that can be exchanged for food. The scale went from zero to one, with one being the most supportive.

Respondents were randomly assigned four different sets of information about food stamps. One group read policy arguments for food stamps, without any party labels attached. Another group did not read policy arguments, but were told that Democrats supported food stamps while Republicans opposed them. A third group got both the policy arguments and the party labels. And a fourth group, which social science calls “the control condition,” got neither.

AD

AD

In this experiment, we defined “ideological sophistication” as adopting the ideology of one’s party.

The figure below shows how those four approaches affected Democrats and Republicans. Without partisan labels, Democrats who say they are conservative tend to oppose increased food stamp funding. Liberal Democrats needed either a label or a policy argument in favor of food stamps; otherwise, they opposed the increase.

Republicans’ reactions could not be more different. After reading the policy argument, conservative Republicans strongly opposed increased funding for food stamps; without reading the argument, they neither opposed nor supported an increase in spending. In a word, for conservative Republicans, party label and policy arguments aren’t needed. They have internalized what policy goes with what ideology, and why.

Many political scientists argue that Americans are “innocent of ideology” — that is, that they do not have a solid grasp of the ideological structure of American politics. Our results complement that conventional wisdom, in several ways. First, this is a study of partisans, not of the general citizenry. Second, in the past, political science has usually treated political ideology as the same as political cosmology — having an interconnected system of abstract beliefs about the dynamics of politics and the economy. Our definition is much simpler.

AD

AD

The Democratic Party has offered more policies that most Americans support. But the Republican Party has more supporters who are ideologically aware. That has power.

Yphtach Lelkes is an assistant professor at the Annenberg School for Communication, University of Pennsylvania. Follow him on Twitter @ylelkes.