Rod Laver is the only man to achieve a true Grand Slam

The argument

In discussions of the greatest tennis players of all time, players who competed before the beginning of the sport's Open Era in 1968 are often neglected due to the difficulty of comparing their achievements to those who came later. Prior to the Open Era, amateur and professional players competed separately, complicating the picture of who was truly the best in the sport. The achievements of Rod Laver, however, effectively cut through these complications. Laver is the only player in the Open Era to have accomplished the greatest feat in tennis, winning all four Grand Slam tournaments in the same year, a Calendar Year Grand Slam. In fact, Laver's 1969 Calendar Year Grand Slam was his second, as he had already won all four in the same year as an amateur in 1962, and he also won all three Pro Slams as a professional in 1967. The confusion about how to rate players' success which stems from the pre-Open Era split between amateurs and professionals is thus irrelevant with respect to Rod Laver. He beat all the best amateurs as an amateur, he beat all the best professionals as a professional, and then he beat all the best of both once the Open Era started. Laver proved himself the greatest across different eras, and he should therefore be considered the greatest of all time.

Premises

Counter-arguments

Advocates of the modern greats argue the calendar Grand Slam, though extraordinary, is one criterion among several, and that on the fullest measures Laver is outranked. Novak Djokovic, Rafael Nadal and Roger Federer each amassed far more major titles than Laver — Djokovic passing 24 Slams — along with sustained dominance over deep fields, weeks at world number one and decorated head-to-head records; Serena Williams's tally similarly dwarfs his. A single-year sweep is a spectacular achievement, but 'greatest' is usually judged on the totality of a career. They add that Laver's amateur-era feats came against a split field: the best players had turned professional and were barred from the amateur Slams, so his 1962 amateur Grand Slam was won without the strongest competition. Comparing eras is genuinely hard, but that difficulty cuts both ways — it does not automatically resolve in Laver's favour, and the depth, professionalism and physical standards of the modern game are frequently cited as reasons the recent champions have the stronger case.

Rejecting the premises

[Rejecting P2] Critics note Laver's 1962 amateur Grand Slam was won while the best players were barred as professionals, so it came against a weakened field, qualifying its weight. [Rejecting C] The calendar Slam is one criterion; on total majors, sustained dominance and time at number one, Djokovic, Nadal, Federer and Serena Williams rank ahead, so 'only man with a true Grand Slam' does not settle 'greatest of all time.'