(Paul J. Richards/AFP/Getty Images; David Goldman/AP)

For all the differences between Hillary Clinton and Donald Trump during Monday night’s debate (the groan! the shoulder shimmy!), perhaps the most stark was the willingness to get specific.

In the immediate post-debate analysis, observers concluded that Clinton had played the policy wonk, more comfortable discussing the specifics of her proposals than articulating broader rhetorical themes. “When it gets to policy, it can’t just be three things,” New York Times columnist David Brooks said on PBS. “It has to be 16 things, and [she] gets into laundry list mode.”

Trump brought no laundry list. He repeated the central theme of his campaign — “I want to make America great again” — but demonstrated little command of facts and policies. Trump hadn’t “given lots of thought to NATO” before running for president, struggled to take a clear position on whether the United States should modify its policy governing the use of nuclear weapons, and mocked Clinton for posting her proposal for defeating the Islamic State on her website. “I don’t think General Douglas MacArthur would like that too much,” he said.

As Perry Bacon Jr. of NBC News observed, Trump “has released far fewer detailed policy proposals [than Clinton] and speaks more in generalities about his vision for governing.”

Clinton and Trump were playing to type. In our new book, “Asymmetric Politics: Ideological Republicans and Group Interest Democrats,” we show that Democratic candidates run by appealing to group identities, emphasizing policy specifics and promoting a pragmatic approach to governing. Republicans, on the other hand, rely on broad ideological themes and vow to stick to their principles rather than compromising with the opposition.

These differences grow from two very different approaches to politics.

Democrats emphasize policies for groups; Republicans emphasize principles

The groups that make up the Democratic coalition view the party as standing up for their particular political interests. They pressure Democratic candidates to commit themselves to specific issue positions that will further these interests. They prefer pragmatic governance that delivers concrete progress on this policy agenda.

And Democratic politicians respond. They sell themselves to voters with detailed policy proposals and by explicitly invoking the social groups they are vying to represent, as Hillary Clinton did during the 2016 primaries. She even characterized her primary opponent Sen. Bernie Sanders as a “single-issue candidate” because of his focus on regulating Wall Street and changing the campaign finance system. And it worked: Clinton’s strong support from key Democratic groups — particularly women and racial minorities — helped her hold off Sanders’s challenge.

The group focus of the Democrats was on display at the party’s convention this summer. Speakers represented African Americans, Asian Americans, Native Americans, gays and lesbians, transgender people, Muslims, millennial-generation voters, and people with disabilities.

Republican candidates, in contrast, rarely make appeals to specific groups a centerpiece of their campaigns. Instead, they emphasize broad, symbolic themes, with an eye toward mobilizing voters based on ideological predispositions.

Consider the figure below. It shows the frequency with which Republican and Democratic candidates in primary debates from 1999 through 2012 mentioned particular themes. Republicans are more likely than Democrats to use the language of ideology, principle and American imagery (such as the flag, national virtues or threats to the American way of life) in primary debates. Democrats cite specific demographic and interest groups.


 

In general election debates, these differences become more muted, in part because both candidates are appealing to the same set of voters. But, as the figure below shows, Democrats remain more likely to invoke group identities and mention policy specifics, as Clinton did Monday. Republicans remain somewhat more likely to cite ideological principles and values.


How Trump is — and is not — a typical Republican

Which brings us back to Trump.

While the New York businessman has diverged from the typical Republican playbook — spending little time warning against big government or extolling the virtues of individual liberty, for instance — he has in many ways adopted the standard GOP approach. His campaign is built around a broad theme of American nationalism applied to immigration, foreign policy, international trade agreements, terrorism and culture.

Trump won the Republican presidential primaries by running to the ideological right of his opponents on his signature topic of immigration. He was the Republican candidates’ most outspoken critic of President Obama, who many conservatives believe isn’t patriotic enough and is too soft on terrorism.

Trump’s aggressive affect, his hyperbolic rhetoric (“We don’t have a country anymore!”), and his disdain for incremental change — all on display during the debate last night — contrast sharply with Clinton’s more pragmatic and policy-oriented style.

But while many commentators see these differences as merely reflecting Clinton and Trump’s distinct personalities, experiences and philosophies, it’s more accurate to view the two candidates as personifying a more enduring difference between the parties they were chosen to lead.

Matt Grossmann is director of the Institute for Public Policy and Social Research and associate professor of political science at Michigan State University. Find him on Twitter @mattgrossmann.

David A. Hopkins is assistant professor of political science at Boston College and blogs about U.S. politics at Honest Graft.

Together they are the authors of “Asymmetric Politics: Ideological Republicans and Group Interest Democrats,” recently published by Oxford University Press.