Before we begin, for the record, I am anti doping. I am also against spurious arguments that are accepted at face value without critical analysis.
To the first point, I can’t really say why I am anti doping, other than if you allow doping, it would no longer be sport. Unfortunately, that may be the best argument against doping. Which leads me to the second point.
I accept that there are very strong pro doping arguments. Unfortunately, I hardly ever see them. Mostly, I have to (ok, I don’t have to) read ridiculous ones. Where to begin…
“We obviously can’t stop it, we might as well allow it.” This argument could literally be used for every single law and rule that human beings have ever created. Of course, you can’t stop it. That is exactly the reason there are rules and laws.
“Prohibition doesn’t work, we should regulate it.” A variation on the first argument, and equally ridiculous although for different reasons. It misses two very important points. Prohibition IS regulation, with the allowed limit set at zero. If you put the limit at any other (arbitrary) point than zero, you change exactly nothing in terms of policing. Actually, I take that back. You would make policing even more difficult. It is difficult enough to make a case if the presence of a substance is prohibited completely. Imagine for a moment the chaos of somehow trying to prove a positive test at a point other than zero. Secondly, there will always be people prepared to cheat. Again, that is why there are rules in the first place.
“Everyone else was doing it.” Ok, not technically an argument in favour of doping per se. Officially the only argument that your parents will not accept as an excuse for misbehaviour when you are six years old, but works on everyone else when you are an adult found guilty of doping.
As with more or less everything, the debate / discussion on doping is hopelessly superficial. Reality is infinitely more nuanced and many of the lines drawn between allowed and non allowed are completely arbitrary. One rational discussion on the topic is here, in the form of a podcast featuring Bill Simmons and Malcolm Gladwell. And even if you’re not interested in the topic, it’s Simmons and Gladwell; there are dozens of worse ways to spend an hour.