Is Phelps really the greatest?
For some people, it's a question that's already been answered.
The greatest Olympian of all time? Michael Phelps, simply because of those unmatched 11 gold medals.
Done deal. Or is it?
By some calculations, Phelps isn't even the most successful Olympic athlete of all time. Gymnast Larissa Latynina has the bigger overall medal haul by five, even if she has a mere nine golds sprinkled in among her total of 18.
Phelps, of course, might bag another three in the next few days - but stats can only ever tell part of the story.
If we're talking Olympics, there are other factors we need to bring in - the competitiveness of the event, the difficulty of competing in multiple medal races, the era in which it took place.
Then there are the more nebulous aspects of being a great Olympian: sportsmanship, demeanour, post-career reputation.
Let's line up a few contenders.
In terms of medals alone, Carl Lewis's record is impossible to argue with: nine golds, spread over 12 years, with seven of them coming in individual events. Phelps currently has six golds from solo swims and five from relays.
Lewis also scores well for consistency, winning his first long jump gold at the age of 23 and his fourth aged 35.
Whether his golds in Los Angeles are devalued by the Eastern Bloc boycott is debatable. He had won the 100m, 4x100m and long jump at the inaugural world championships the previous year and had been ranked no.1 in the world over 100m since 1981.
What is unarguable is that he tested positive for banned substances three times before the 1988 US Olympic trials, initially being banned from the Seoul Olympics before being let off with a warning.
Lewis's own reaction - "There were hundreds of people getting off," does little to protect his reputation, and brings to mind the famous line from Ed Moses after the '84 Olympics, when he said of his team-mate: "Carl rubs it in too much. A little humility is in order."
Jesse Owens only ever had the chance to compete at one Games.