First of all, I strongly suspect the question of who is the greatest Olympian will a have a definitive answer four years from now. Phelps has indicated in interviews that he will compete in London in 2012. I do not think it is a stretch for one to envision him winning another five or six gold medals, and maybe even eight again. That could give him 20 gold medals.

I cannot speak for the whole world (although I would like to), but this would end the discussion for me. Although, admittedly, if longevity equalled greatness, then some would still argue for little-known Hungarian fencer Aladar Gerevich. All Gerevich did was win gold medals at SIX consecutive Olympics – from 1932 until 1960, the last one at age 50 (all the more amazing since there was no Olympics in 1940 and 1944). And let’s not forget Milo of Croton (since this is an all-time question), a late 6th century BC wrestler who won five straight Olympic titles.

Right now, however, I think you can still have fun with this question even though comparing different sports, different generations and different levels of amateurism and professionalism is even worse than comparing apples and oranges.

Obviously, some sports allow certain athletes to win more medals because of the multiple categories available within that particular sport. Swimming, gymnastics and, to a lesser extent, track and field (athletics), appear to have the most opportunities to win multi-events within a single Olympics.

Modern athletes are actually at a disadvantage because the competition is so much stiffer. Jim Thorpe (perhaps the greatest all-around athlete since 1900), Ray Ewry (eight gold medals in track and field in the early 1900s), Finnish distance runner Paavo Nurmi (nine golds, 12 medals in total, two of them 26 minutes apart!), Jesse Owens and Soviet gymnast Larissa Latynina (nine golds, 18 in total) are all great athletes, but did not face nearly as much competition as the athletes in Beijing. And, unlike Carl Lewis (nine gold, 10 in total), Jesse Owens' Olympic career was interrupted by WWII.

Phelps makes money on endorsements and can continue his swimming career – an option Mark Spitz (seven golds, nine in total) did not have in 1972. Both Thorpe's and Nurmi's careers were cut short due to accusations of professionalism. Hence, while Phelps might (most golds – Latynina still has most medals) be the most decorated summer Olympian, he has had some advantages (and, perhaps more importantly, no disadvantages) over other athletes.