Author Jared Cohen discusses his new book on eight U.S. vice presidents who ascended to the presidency and how they fared in that role.

There were eight times in history when a sitting American president died and the vice president assumed the highest office in the land. These men were not elected to be head of the country and, in some cases, weren’t even the first choice of their own party. Yet they changed the course of history and the political narrative of the country. These men were John Tyler, Millard Fillmore, Andrew Johnson, Chester A. Arthur, Theodore Roosevelt, Calvin Coolidge, Harry Truman and Lyndon B. Johnson. A new book looks at what they accomplished and why half of them were subsequently elected. Accidental Presidents: Eight Men Who Changed America was written by Jared Cohen, CEO of Jigsaw, the technology incubator at Google parent company Alphabet. Cohen also spent five years as a member of the secretary of state’s policy planning staff and was a close adviser to both Condoleezza Rice and Hillary Rodham Clinton. He recently spoke about his book on the Knowledge at Wharton radio show on Sirius XM. (Listen to the podcast at the top of this page.)

An edited transcript of the conversation follows.

Knowledge at Wharton: Your role is as CEO of Jigsaw, but it sounds like American history is very much an interest of yours. What was the impetus for writing this book?

Cohen: When I was eight years old, my parents bought me a children’s book about the presidents. When you’re an eight-year-old and you’re reading a book about the presidents, it’s supposed to be an innocent experience. But I zeroed in on the eight instances where a president died, and my poor parents had to have these conversations about death and assassination. I never quite let it go.

When my wife was pregnant with our eldest daughter, I needed a nesting activity. After a life of reading presidential biographies related to these abrupt transfers in power and collecting presidential memorabilia — including locks of presidential hair, which is weird — I decided this was going to be my nesting activity. There’s something nice about being the CEO of an organization in an industry focused entirely on the future, and spending my down time reading about John Tyler, Millard Fillmore, Teddy Roosevelt and Calvin Coolidge. It’s very therapeutic and good for the soul.

Knowledge at Wharton: In looking at this list, one vice president who was not on your list was Gerald Ford, who took office after Richard Nixon resigned. Why not include him?

Cohen: I debated this when I started writing the book, and what I concluded is the thing that was most interesting and most compelling was the unexpected and abrupt transfer of power. If you look at the Nixon-to-Ford transition, it didn’t happen upon the death of the president. It was sort of drawn out. It was related to scandal and resignation. It’s that abrupt, dramatic, unexpected death in office that throws the country into a tailspin and elevates a man nobody thought was going to be president. In the case of Ford, so long as the Watergate hearings were happening, and in the lead-up to it, people began to experience the idea and get used to the idea that Ford might become president.

Knowledge at Wharton: Four of these men were reelected to the presidency, so we have some examples of vice presidents who became presidents and did a very good job. But you also have examples of ones that didn’t have a great time as the chief executive.

“It’s that abrupt, dramatic, unexpected death in office that throws the country into a tailspin and elevates a man nobody thought was going to be president.”

Cohen: That’s correct. What I’m struck by in writing this book is how we basically winged presidential succession. You don’t have the 25th Amendment formalizing the fact that the vice president becomes president when their predecessor dies in office until after John F. Kennedy is assassinated. So, you get these men who are thrust into power, who were thrown on the ticket either as a punishment — in the case of Teddy Roosevelt — or because they were the available man, in the case of Millard Fillmore. But in each instance, they rose to the pinnacle of power at some of the most seminal moments in our history.

Let’s take Abraham Lincoln. Abraham Lincoln is assassinated towards the tail-end of the Civil War, and we’re supposed to get his vision for Reconstruction. Instead, the bullet of John Wilkes Booth gives us Andrew Johnson, the last president to own slaves. Instead of following Lincoln’s path, he ends up resurrecting many elements of the Confederacy.

Knowledge at Wharton: Of these eight men, who do you think was probably the most accidental of the accidental presidents?

Cohen:  John Tyler certainly was the most accidental because the framers hadn’t thought much about the vice presidency and didn’t really want one in the first place. The vice president was added at the last minute as an electoral mechanism. When William Henry Harrison dies after just 30 days in office, John Tyler has to race back from Virginia because there’s a debate that ensues with the Cabinet about whether he’s the president or the acting president. He has to spend his first months in office debating with Congress why he’s not acting president.

He ends up setting a precedent that is followed seven more times — including all the way up to LBJ — and it ends up disastrously. Tyler is not really a Whig but is thrown on the ticket to win Virginia, which they lost, and to give a nod to the state’s rightists. He ends up getting kicked out of the party. And in a moment of political rage and animosity, he decides to annex Texas and precipitate war with Mexico.

Knowledge at Wharton: Was Harry Truman probably the most predictable of this group because of President Franklin Delano Roosevelt’s failing health?

Cohen: Harry Truman was both the most predictable and, in many respects, the most ill-prepared for the moment. Remember, he’s thrown onto the ticket because the party bosses know FDR is going to die and they can’t fathom the idea of Henry Wallace, who’s seen as a Soviet sympathizer and ultra-liberal, ending up as president. So Truman, during his 82 days as vice president, meets FDR twice. He doesn’t get a single intelligence briefing, doesn’t meet a single foreign leader, isn’t briefed on the Manhattan Project, isn’t read into the War. And then he wakes up on April 12, 1945, and finds himself as president at the height of the war in the Pacific. He’s trying to figure out how to engage with Churchill. Stalin is reneging on every one of his promises from Yalta, and yet Truman ends up being a remarkable success. He has to make more seminal decisions in his first four months in office than probably any president who came before him.

Knowledge at Wharton: One of the big themes in the book is the 25th Amendment, which is getting some conversation right now. But this goes back to the days of LBJ and JFK. Can you talk about the importance you think that the 25th Amendment has had on the presidency?

Cohen: What’s amazing is the 25th Amendment gets passed at the end of LBJ’s administration, and the first time it gets put into motion is actually not for the president, but the vice president. When Spiro T. Agnew resigns from office, Richard Nixon uses the 25th Amendment to replace him with Gerald Ford and essentially pluck him from Michigan’s 5th district. What’s fascinating is of the eight accidental presidents, six of the vice presidents who ascended nearly died in office themselves. Yet there is no provision for replacing the vice president of the United States until the 25th Amendment.

This was this sustained constitutional vulnerability that we left ourselves exposed to for most of the history of the republic. The time that the 25th Amendment really should have been put in place was when Reagan was shot. When Reagan was shot in ’81, the Cabinet made a decision that it was a dangerous precedent for them to set to decide that Reagan was disabled, so they chose not to evoke the 25th Amendment. That’s how you get the kind of Al Haig-type moments.

What’s interesting is that the 25th Amendment has only been exercised in terms of presidential disability for colonoscopies. We’ve yet to see an instance of the amendment being evoked to temporarily discharge the duties of president to the vice president for any instance other than a colonoscopy.

Knowledge at Wharton: When you look these different examples, JFK/LBJ is probably one of the most talked-about and remembered because of its timing in the 1960s and the fact that it happened in the age of television.

Cohen: When I interviewed the Rev. Jesse Jackson for the book, he said that when he had learned of JFK’s assassination, he felt like it was a double assassination. One, the president of the United States and two, civil rights. People expected LBJ to be a disaster for the Civil Rights Movement, and what proved to be true was that the Kennedys were prepared to pay lip service to civil rights, but they weren’t really willing to back it up with real action — particularly not in the lead-up to the 1964 elections.

“Andrew Johnson proved to be the biggest disaster of all of the accidental presidents.”

I do believe, and I write about this in the book, that had Kennedy survived, it’s very unlikely you would have had the 1964 Civil Rights Act. I also think that we overstate this idea that Kennedy wouldn’t have gone down the same slippery slope in Vietnam that LBJ did. I think that that’s largely architected by the guardians of Kennedy’s reputation.

If you look at the history of succession in this country, we look at the assassination of JFK as this incredibly dramatic moment in history because it’s the most recent and something that played out on television. But when you dig into the impact that assassination had at other times in our history — Lincoln, Garfield, McKinley — there was a similarly dramatic impact and sustained period of mourning that ensued. We just have forgotten what that’s like because we’re in the longest period of time without a president dying in office.

Knowledge at Wharton: How should Andrew Johnson should be remembered in his term following Lincoln?

Cohen: Andrew Johnson proved to be the biggest disaster of all of the accidental presidents. When we look at how we winged presidential succession throughout history, we got pretty lucky in navigating it through, except for the Andrew Johnson moment. And it was a moment of great significance.

Johnson was put on the ticket in 1864 because he was the only Southern senator who had stayed loyal to the Union. He wanted to put the Union back together so badly that his rhetoric on civil rights and punishment of traitors was even more forward-leaning than Lincoln’s. But once a racist, always a racist. Remember, he was the last president to own slaves. When the Civil War ended, his true colors showed and he ended up giving amnesty to almost everybody, delegating civil rights to the states that paved the way for the black codes, which were the precursors to the Jim Crow laws.

The interesting thing about Andrew Johnson — an amazing story that few people know — he was completely inebriated when delivering his oath of office as vice president. He stood up there completely hammered, insulting every single person there. Lincoln’s head is buried in his hands. He can’t remember the names of certain members of the Cabinet. He slobbers all over the Bible with like a drooling kiss. When they go outside, Lincoln points out Frederick Douglass, who at the time is the most famous ex-slave in the country. Frederick Douglass writes in his autobiography that, “I looked at the glare in that man’s eyes and I knew that he was no friend of my race.” What Douglass didn’t realize is the glare in his eyes was that he was completely hammered. But the conclusion was correct, that Andrew Johnson was no friend of his race.

“If you put him in modern-day context, Teddy Roosevelt is as fascinating as he is crazy.”

Knowledge at Wharton: Was he shocked to find himself taking over the office of the president?

Cohen: Today, in an era of social media, the vice president would know immediately that they’re president. In the case of Andrew Johnson, the knock comes on his door. He’s supposed to be assassinated that night as well, except George Atzerodt, who was his would-be assassin, got drunk at a nearby tavern.

Andrew Johnson goes to the Petersen home, where Abraham Lincoln is on his deathbed. Everybody there knows Andrew Johnson is going to be president of the United States because everybody knows Lincoln is dying. But he’s asked to leave the room because he’s making Mary Todd Lincoln uncomfortable.

Then when he takes the oath the next day, Mary Todd Lincoln refuses to leave the White House for many weeks. She auctions off most of the items in the White House. Then a week later, Andrew Johnson ends up so incredibly ill that he ends up more or less on a deathbed. They notify the president pro tempore who’s out West — a man named Lafayette Sabine Foster — and tell him that he needs to rush back to Washington because Andrew Johnson might die.

Knowledge at Wharton: Is there one that is the least recognized accidental president?

Cohen: I think the one that’s most interesting and least talked about and relevant for today is Calvin Coolidge. If you look back at history, the most scandalous administration in the history of our republic was the Warren Harding administration. You had Teapot Dome. You had a massive scandal at the Veterans Bureau. The attorney general was complicit in everything from fight fixing, stock manipulation, bootlegging and various other shady activities. And Warren Harding dies out West — an incredibly popular man — but the scandals in his administration are a ticking time bomb that threatens to destroy the Republican party and his administration.

Calvin Coolidge ascends to the presidency. He finds out about all the scandals a couple of weeks into the presidency. You have less than a year before the 1924 election, and the scandals break three months later. So, Calvin Coolidge does something very clever, which is he cultivates an image of himself so boring and so irrelevant — what’s called Silent Cal — that “I couldn’t have possibly been involved in any of this.”

He sailed to victory in 1924. The economy was booming to such an extent in the 1920s that I don’t think that Americans cared if it was Warren Harding, Calvin Coolidge, Herbert Hoover in the early years, whether there were scandals, whether it was clean as long as the good times were rolling in. I think the lesson for today is that the economy trumps scandal.

“The lesson for today is that the economy trumps scandal.”

Knowledge at Wharton: Chester Arthur succeeded James Garfield, and it was thought that he was not going to have a great presidency. But he did OK because he followed the path laid out by Garfield, correct?

Cohen: You have never seen a bigger turnaround in the history of the republic than the turnaround of Chester Arthur after he ascended to the presidency. James Garfield was the only man ever to get the nomination for his party and win the presidency without seeking it in the first place. When the party bosses got frustrated between a debate over Ulysses S. Grant and James Blaine, Garfield’s name was thrown into the hat and he ended up as the nominee against his will. He’s one of the most beloved men in the country by both parties — by all sections, by all races — and then he’s shot by an insane office-seeker four months into his presidency.

Chester Arthur was a machine politician who was so vain that he changed the year of his birth to seem younger. He’d spent his entire time as vice president undermining Garfield. He cared more about patronage in New York than he did his own administration and thwarted it at every step. There’s a scene where Chester Arthur and machine boss Roscoe Conkling barge into President-elect Garfield’s room at 1 a.m. on the eve of his inaugural address to intellectually rough him up. But when Garfield is assassinated, Arthur has to more or less go into hiding for a month and change because people are blaming him for the assassination, since the assassin claimed to do it on behalf of Arthur.

Then something amazing happens. Since we like to talk about trolling as it relates to the president today, Arthur is impacted by the very first average citizen to troll the president and get a reaction. A woman named Julia Sand, who lived on the Upper East Side of Manhattan, wrote him these long letters telling him what a despicable man he was, but that there was still hope for him — comparing him to some of the worst characters in the court of Henry VIII. We know that these letters had an impact on Chester Arthur because one day he showed up in his presidential carriage outside of her townhouse on the Upper East Side of Manhattan and went in and spent some time with her.

Knowledge at Wharton: Where do you put Teddy Roosevelt in this mix?

Cohen: Teddy Roosevelt is the only one of the accidental presidents who almost certainly would have ended up as president himself, but he waited too long to join the 1899-1900 campaign. Teddy Roosevelt is your classic example of somebody who ended up in the vice presidency as a containment strategy by New York party bosses who wanted to punish him by exiling him to the political equivalent of Elba.

But Teddy Roosevelt was such an outsized personality for his day. Two things happened as a result of his presidency. One, he ushered in an era of progressivism that probably wouldn’t have been ready for election in 1901, when he ascended to the presidency. He also fundamentally changed the scope of U.S. foreign policy. But we should consider ourselves fortunate that Teddy Roosevelt didn’t preside over a war as president. If you put him in modern-day context, he is as fascinating as he is crazy. And his fascination with war and his love for war and adventure would have been a dangerous thing as commander-in-chief.

“We still treat the vice president as a marriage of political convenience when a candidate needs a bump in the polls.”

Knowledge at Wharton: You spent a chapter in the book also looking at close calls, including when President Ronald Reagan was shot and survived. How important is it to also cover that part of the story?

Cohen: One of my frustrations in writing the Accidental Presidents is that we didn’t learn our lesson at any step of the way, and we allowed this constitutional vulnerability to sustain.

When I talk about 19 close calls, in addition to the eight presidents who died and four who were assassinated, these are legitimately close calls. We’re talking about Andrew Jackson shot at point blank and the gun malfunctioning. We’re talking about Gerald Ford shot at point blank, and then a second time from a distance. One time the gun malfunctioned.

There is an incredible story of FDR as president-elect. He’s giving a speech in Miami in February of 1933. He’s sitting on the back of the Buick in his three-car motorcade, and a man named Giuseppe Zangara fires five shots in 15 seconds at him. A 100-pound woman named Lillian Cross saw him pull out the gun and smacked him with her purse. It thwarted his aim. He missed FDR by about 3 inches. He ends up killing the mayor of Chicago who’s in town, as well as three or four others. But this extraordinary woman and her purse saved the New Deal.

There’s another amazing story where President-elect Kennedy was stalked by a disgruntled postal worker. It doesn’t get more cliché than that. He filled his Buick with enough dynamite to blow up the entire city block outside of his house in Palm Beach. He didn’t end up going through with it because, as Kennedy came to the door to go to church, he saw one of the Kennedy children there and felt bad. He follows JFK to the church, fills his pants with dynamite, has his hand on the trigger in his pocket and is ready to do it standing 4 feet away from the president-elect — and then sees a bunch of children and once again doesn’t do it. It’s extraordinary. For all the talk about suicide bombing and so forth in the context of modern terror, we almost had one of our most famous presidents as president-elect killed by a suicide bomber.

Knowledge at Wharton: It’s notable that we’ve gone so long now without having a president assassinated.

Cohen: Yet isn’t it amazing that, as we enter the 2020 election, we have the oldest president in the history of the country and two of the most serious contenders on the Democratic side both in their late 70s. My conclusion is I still don’t think we’ve learned very much from our history. We still treat the vice president as a marriage of political convenience when a candidate needs a bump in the polls. If you look at the various gimmicks of coming out of the gate with a running mate or what was tried with Sarah Palin with John McCain — so long as it’s the sole choice of the campaign and not the choice of the party, it’s going to continue to be viewed as an election ploy.