How different are dogfighting and football?

Gladwell compares dogfighting and football.

History:

In 1905, President Theodore Roosevelt called an emergency summit at the White House, alarmed, as the historian John Sayle Watterson writes, “that the brutality of the prize ring had invaded college football and might end up destroying it.” Columbia University dropped the sport entirely. A professor at the University of Chicago called it a “boy-killing, man-mutilating, money-making, education-prostituting, gladiatorial sport.” In December of 1905, the presidents of twelve prominent colleges met in New York and came within one vote of abolishing the game.

NFL offensive lineman says:

I remember, every season, multiple occasions where I’d hit someone so hard that my eyes went cross-eyed, and they wouldn’t come uncrossed for a full series of plays. You are just out there, trying to hit the guy in the middle, because there are three of them. You don’t remember much. There are the cases where you hit a guy and you’d get into a collision where everything goes off. You’re dazed. And there are the others where you are involved in a big, long drive. You start on your own five-yard line, and drive all the way down the field—fifteen, eighteen plays in a row sometimes. Every play: collision, collision, collision. By the time you get to the other end of the field, you’re seeing spots. You feel like you are going to black out. Literally, these white explosions—boom, boom, boom—lights getting dimmer and brighter, dimmer and brighter.

Brain Doctor says:

She pulled out a large photographic blowup of a brain-tissue sample. “This is a kid. I’m not allowed to talk about how he died. He was a good student. This is his brain. He’s eighteen years old. He played football. He’d been playing football for a couple of years.” She pointed to a series of dark spots on the image, where the stain had marked the presence of something abnormal. “He’s got all this tau. This is frontal and this is insular. Very close to insular. Those same vulnerable regions.” This was a teen-ager, and already his brain showed the kind of decay that is usually associated with old age. “This is completely inappropriate,” she said. “You don’t see tau like this in an eighteen-year-old. You don’t see tau like this in a fifty-year-old.”

Dog-fighting in society:

It’s the shot ringing out that seals the case against dogfighting. L.G. willingly submitted his dog to a contest that culminated in her suffering and destruction. And why? For the entertainment of an audience and the chance of a payday. In the nineteenth century, dogfighting was widely accepted by the American public. But we no longer find that kind of transaction morally acceptable in a sport.

Is the difference in judgement on pain for entertainment based only a matter of time?