With that uncertainty in mind, it's worth going through a handful of things that we do know about Biden's mindset as he nears the biggest decision of his political life.
1. Biden would like to be president
How do I know? Because he's run twice before — 1988 and 2008 — and the best indicator of running for president in the future is having run for president in the past. And the desire to be president is not something that goes away. In the words of the late senator Estes Kefauver (D-Tenn.): "Presidential ambition is a disease which can only be cured by embalming fluid." Biden has been in politics his entire adult life; anyone who is that deep in the game for that long wants to get to the top of the mountain — especially when that person is as close to the peak as Biden is right now.
2. Biden is aware of history
The last eight years have taken a political story with a disappointing ending — Biden, the man with so much ability and appeal, never coming close to the White House — and turned it around. Rather than simply playing out the string in the Senate, Biden has spent the last almost-decade as one of the most powerful politicians in the country — and can rightly claim credit for nudging his boss along on same-sex marriage, among other issues. That's a nice final chapter for Biden's political life. Less nice would be a presidential bid that never really got off the ground and left him as, at best, a spoiler to Clinton. That, at least looking at the available data, is the most likely outcome if Biden does decide to run. Is that the career coda he wants?
3. Biden would never have seriously considered the presidential race if Beau Biden were healthy
Ask anyone even remotely close to Joe Biden whether he runs for president again if his eldest son was, right now, on the way to becoming the next governor of Delaware, and they will all tell you, no way. Joe Biden saw Beau Biden as the one who would carry the Biden name and "Biden values" onto the national stage. (In Joe's defense, lots of other people saw Beau Biden as potential presidential material as well.) His son's illness and untimely death in May — not to mention Beau's reported desire to see a Biden on the ticket in 2016 — totally altered the glide path that Biden was on in his final few years of the Obama administration. Now there is no next Biden in line; it's Joe.
4. Biden believes he is a better candidate than Hillary Clinton
Put aside Clinton's excellent debate performance last week and the fact that, generally, she is a skilled and able debater. Biden is far more of a natural on the campaign trail than Clinton — and knows it. There's no question that Biden is occasionally (okay, more than occasionally) too honest and/or too blunt for his own good. And that, as an actual presidential candidate — in 1987, he was driven from the race amid plagiarism allegations, in 2008 he was a total non-factor — he has been less than impressive. But Biden feels — somewhat rightly — that his common touch is exactly the sort of thing that would further complicate Clinton's attempts to come across as authentic.
5. Biden sees himself as the natural heir to Obama
For all of Clinton's attempts to cozy up to Obama in the first debate last week, Biden views himself as the best steward of the sort of politics and policies that the current president believes in. Biden is the one, after all, who has spent the last seven years at Obama's side, making the case for his policies around the country and around the world. If there is popularity to be transferred from Obama to anyone, Biden believes it's him.
6. Biden is genuinely of divided mind
There's a reason Biden is taking longer than he probably should to make up his mind about the race: He genuinely doesn't know what to do. Biden knows that, at 72, this is without question the last shot he will have at running for president. He also knows that Clinton's stumbles have opened a window of opportunity for him that looked unimaginable a year ago. But he and his family continue to grieve the loss of Beau. And while there is a path for Biden to get the nomination, it goes directly through Clinton — meaning a direct frontal assault on the front-runner. My guess is that Biden has changed and rechanged his mind about whether to run 20 times since this summer — and might even change it between now and when he makes his decision public.