This article was originally posted at Providence.

“Donald Trump’s ideas aren’t just different,” Hillary Clinton told an audience in San Diego yesterday. “They are dangerously incoherent.” There are several truths, bitter and profound, about Clinton’s speech in which she excoriated Trump for his foreign policy views. Taken together, they point to an almost unprecedented crisis in American political leadership that cuts across party lines.

The first truth is that Clinton, the presumptive Democratic nominee for president, is essentially correct about the presumptive Republican nominee. Trump’s foreign policy statements are indeed “dangerously incoherent” and, if implemented, would create a much more unstable and violent world.

Tired of seeing the United States bear the burden of providing security for our allies, Trump would allow a nuclear arms race in Asia—as if America’s careful stewardship of its nuclear dominance has done nothing to promote international security in the region. Resentful that our NATO allies fail to invest adequately in their own defense, he would encourage the dismantling of NATO—despite it being the most successful political-military alliance in history. He would order the military to torture and murder civilians related to terrorists—a war crime under international law. He would approve a ban on all Muslims trying to enter the United States—a repudiation of centuries of American immigration policy that plays into the hands of radical Islamic extremists.

Clinton also accused Trump of being “temperamentally unfit” for the office of president. “Now imagine Donald Trump sitting in the Situation Room, making life-or-death decision on behalf of the United States,” Clinton said. “Imagine him deciding whether to send your spouses or children into battle. Imagine if he had not just his Twitter account at his disposal when he’s angry, but America’s entire arsenal.”

Can even Trump’s most rabid supporters ponder this scenario without a twinge of anxiety? The power of the American presidency is like none other on earth. It is a certainty that Trump’s worst vices—his crudeness, his infantile attacks on critics, personal grudges, unchecked egotism—would be magnified the day he took office. Yes, try to imagine Trump with his finger on the nuclear button without trembling.

The second truth is that Trump’s ascendancy as the Republican standard-bearer promises to permanently deprive the party of one of its historic advantages over Democrats: its status as the political party most trusted by the American people to navigate the United States in foreign affairs, especially in the face of international crises.

“If America doesn’t lead, we leave a vacuum,” Clinton said. “And that will either cause chaos, or other countries will rush to fill the void.” Trump’s “America First” sloganeering is simply a revival of the morally obtuse isolationism of the 1930s. Under a Trump presidency, America’s indispensable role in promoting democracy and upholding international peace and security—American exceptionalism—would be trampled underfoot. Ronald Reagan’s “shining city on a hill” would slip into a fearful sinkhole of fortress America.

The irony of Clinton’s message, of course, is that she is the messenger. Her critique of Trump’s deficiencies is substantive, detailed, even devastating. Any of Trump’s rivals for the Republican presidential nomination could have delivered it, if only they had the courage of their convictions. But Hillary Clinton, despite her many years in political life, ranks as among the least capable—and least trustworthy—to guide the United States in an unstable and dangerous world.

“Unlike him,” she said of Trump, “I have some experience with the tough calls and the hard work of statecraft.” Yes, as a former Secretary of State, Clinton has experience in foreign affairs. But her experience culminated in a catalogue of duplicity, misjudgments, and failure.

Russia’s aggression in Ukraine, the humanitarian crisis in Syria, the rise of the Islamic State in Iraq, the lethal assault on the U.S. embassy in Benghazi (and the White House’s fraudulent attempt to cover up its blunders), the disintegration of the Libyan state into a terrorist stronghold—Clinton played a role in all of these debacles. Her dissembling about her illicit email account—regardless of the risks to national security—fits the Clinton pattern of ignoring laws and norms that conflict with her political aims.

If America doesn’t lead, we leave a vacuum. Here is a geo-political truth, uttered by Clinton’s own lips, that offers the ultimate indictment of her leadership. The projection of American weakness under the Obama-Clinton White House has indeed created a vacuum—filled by the forces of barbarism and lawless aggression. In the end, Clinton’s foreign policy speech, sober enough about Trump, devolved into prevarications, half-truths, and craven deception about her own diplomatic record.

Thus Americans are faced with two likely candidates for president, a Republican and a Democrat, who are both desperately unqualified for the office. America’s character crisis, long festering, has reached a new depth. We can thank a popular and political culture that worships celebrity and winks at cynicism—a culture of our own making. And we have forgotten, to our great peril, the democratic creed of our nation’s first commander in chief: “Let us raise a standard to which the wise and honest can repair; the rest is in the hands of God.”

Joseph Loconte is an associate professor of history at the King’s College in New York City and the author of A Hobbit, a Wardrobe, and a Great War: How J.R.R. Tolkien and C.S. Lewis Rediscovered Faith, Friendship, and Heroism in the Cataclysm of 1914-1918.