Some political debates are about ideas and issues. The 1858 U.S. Senate debates in Illinois between Stephen Douglas and Abraham Lincoln focused on the future of slavery in America. The candidates talked for a total of three hours in each of seven sessions, exploring, as Douglas put it, the “leading political topics which now agitate the public mind.”

Modern presidential debates owe a debt to Lincoln-Douglas for setting the precedent of candidates jousting on a shared stage, but each election also exists in its own time. And so we’re struck by how different this year’s debates are shaping up compared with contests recent and distant. Two weeks before the first scheduled presidential debate from 8 p.m. to 9:30 p.m. on Sept. 26, the single question agitating the public’s mind is not whose ideas are more substantial or exciting, but something far more prosaic: Who is fit to lead our nation?

If you think about presidential elections since the first televised debate (Kennedy vs. Nixon on Sept. 26, 1960), you find stark contrasts in backgrounds and politics. But we’ve seen nothing like Clinton vs. Trump in terms of the public’s skepticism of both candidates.

Donald Trump, a real estate developer and reality TV star, has no prior experience in public service or even public accountability. His campaign M.O. is to make grandiose promises, avoid specifics about what he’d actually do as president and fill most of the rest of his waking hours with outrageous comments. Then he wakes up the next morning and does it again. A majority of voters find him unlikable and unqualified to be president.

Hillary Clinton, by contrast, is a former secretary of state, senator and first lady, steeped in national leadership experience. Yet her candidacy divides the country more than it unifies voters behind the history-making prospect of electing America’s first female president. Clinton’s problems center on trust and judgment: The head of the FBI cites her for being “extremely careless” for mishandling sensitive e-mails as secretary of state. That scandal feeds a nagging sense that she’s a corner-cutter whose ambitions drive her decisions. A majority of voters find her unlikable and untrustworthy.

This election will go on even if, on a dark and stormy night, many voters wouldn’t invite a stranded Trump or Clinton to sleep on the sofa. The last few days have raised even more questions about each candidate’s capacity to lead. During a televised forum broadcast from the decommissioned aircraft carrier Intrepid in New York, Trump went on a bizarre jag about Putin (the otherwise ruthless Russian dictator who invaded Crimea and supports Iran) being a better leader than President Obama.

Clinton, meanwhile, opened herself anew to criticism by her secretive and misleading management of a medical issue.

The good news is that the debates will provide the biggest stage and least scripted opportunity for voters to assess the candidates. Our view is that given the public’s discomfort with Clinton and Trump, the leading third-party candidate, Gary Johnson of the Libertarians, should be invited to participate.

Regardless of whether Johnson is included, this year’s debates will be historic, because there is an unusually strong chance that they will prove decisive. Trump and Clinton, edging closer in the polls, have a lot to prove to the American public. We won’t be looking for a reboot of Lincoln-Douglas. We’ll be listening for direct, specific answers from each about their respective visions of the presidency.