Donald Trump speaks during a campaign rally on March 19, 2016, in Fountain Hills, Ariz. (Ralph Freso/Getty Images)

For decades, American presidents have used their inaugural addresses to celebrate the values of freedom. In his second inaugural address in 2005, President George W. Bush declared, “The best hope for peace in our world is the expansion of freedom in all the world.” Sixteen years earlier, his father had asserted, “We know what works: Freedom works. We know what’s right: Freedom is right.” President Ronald Reagan said the same at his second inauguration, declaring, “America must remain freedom’s staunchest friend, for freedom is our best ally.”

At his inauguration on Friday, President Donald Trump will take to the podium to declare his aims for his next four years in office. Will he have anything to say about the importance of freedom? Will he depart from decades of Republican Party tradition — and American tradition — by declining to embrace America’s role as the leader of the free world? As a presidential candidate, Trump had almost nothing to say on this score. If he persists in ignoring the United States’ special relationship with these ideals, he risks undermining democrats around the world and damaging American national interests.

The collapse of communism a quarter of a century ago seemed to affirm the triumph of democracy as the only legitimate system. But then, in the 21st century, the wars in Afghanistan and Iraq, followed by conflicts in Libya and Syria, tarnished democracy’s standing, while non-democratic powers — China, Russia and Iran — asserted their regional power and global ambitions. Now the latest challenge to democracy is emerging where we had so long assumed it could not — in Europe and the United States, where democratic institutions suddenly look vulnerable.

Despite recent setbacks, there remain compelling moral reasons to support democracy and human rights around the world. Democracies offer the most accountable system of government, the only tonic for illegitimacy and the best way to offer political participation to the disenfranchised. Democracies are also better at protecting basic human rights, representing the will of the people and checking egregious uses of power. Democratic governments do not commit genocide, do not barrel-bomb their own citizens, do not create refugees and do not starve their people. They also are more stable than other forms of government because they offer a peaceful, institutionalized mechanism for transferring power.

Democracies also provide more prosperity for their citizens than other systems of government. It is more than coincidence that the vast majority of the richest per capita countries in the world, excluding oil exporters, are democracies. On average, democracies have performed just as well as autocracies in generating economic growth over the last half-century in the developing world. China’s recent experience of economic expansion is one of the rare exceptions. Far more often, dictators produce economic basket cases — just see the Soviet Union under Leonid Brezhnev, Cambodia under Pol Pot, Zimbabwe under Robert Mugabe, or China under Mao Zedong.

For these reasons and others, public opinion polls around the world consistently show that majorities of people in almost every country prefer democratic systems to dictatorships, absolute monarchies or theocracies.

Yet even if Trump cares little about the preferences and well-being of others abroad, Americans have selfish reasons for wanting to see democracy in the world survive and expand. More democracy makes Americans more secure and more prosperous.

First, our closest and most enduring allies have been and are today democracies. Democracies are the allies who go to war with us, vote with us in the United Nations, support international treaties and norms that serve our interests. Democratic allies are those most willing to provide for our common defense, be it providing support for our missile defenses against a possible North Korean attack, sharing intelligence with us to fight terrorist organizations, or implementing sanctions with us against Iran or Russia to advance our shared security objectives.

Second, our enemies are and have been dictatorships or political movements espousing anti-democratic ideas. In the 20th century, dictatorships in Germany, Japan and the Soviet Union directly threatened American national security. Every war we have fought has been against autocracies — Germany, Italy, Japan, North Korea, North Vietnam, Iraq, Yugoslavia, Afghanistan and Libya. Never has a democracy attacked us. Today, not all dictatorships threaten the United States, but every entity threatening the United States is a dictatorship or a movement — such as the Islamic State, Al Qaeda or the Taliban — committed to anti-democratic ideas.

Third, the consolidation of democracy after the fall of autocracy enhances American security. The construction of democracies in Germany, Japan and Italy after World War II firmly entrenched our alliances with all of these countries. During the Cold War, the United States partnered with autocrats to contain communism. Yet transitions to democracy in Portugal, Spain, Taiwan, the Philippines, South Korea, Chile and South Africa did not, as predicted, hurt American strategic interests, but instead served to nurture deeper, more lasting relationships. After the collapse of communism, new democracies in Europe have made vital contributions to NATO’s mission in Afghanistan and missile defenses against a possible Iranian attack.

Fourth, the U.S. economy also benefits from successful democratization abroad. Aside from China, democracies are our most important trading and investment partners. The collapse of command economies in the former communist world added billions of dollars’ worth of trade to the world economic system, while also offering new frontiers for American investment. The expansion of a rule-based, market-driven world economy is good for the new entrants and beneficial for the largest economy in this system, the American economy.

If Trump persists in denying the centrality of democratic values, it will be up to the rest of us — members of Congress, nongovernment organizations, private foundations and activists — to fill the vacuum in the pursuit of both our values and interests. We cannot and should not allow this moment of doubt about democracy’s promise to become more than a passing trend.