Last month, at the SeaWorld amusement park in Florida, a whale grabbed a trainer, Dawn Brancheau, pulled her underwater and thrashed about with her. By the time rescuers arrived, Brancheau was dead.

The death of the trainer is a tragedy, and one can only have sympathy for her family. But the incident raises broader questions: was the attack deliberate? Did the whale, an orca named Tilikum and nicknamed Tilly, act out of stress at being held captive in a sterile concrete tank? Was he tired of being forced to perform to amuse the crowds? Is it right to keep such large animals in close confinement?

Tilly had been involved in two previous human deaths. In one episode, a trainer fell into the pool and Tilly and two other whales drowned him. In another, a man who appears to have entered the enclosure at night, when Sea World was closed, was found dead in the pool with Tilly. An autopsy showed that he had a bite mark. One of Tilly's offspring, sold to an amusement park in Spain, has also killed a trainer, as have orcas in other parks.

Richard Ellis, a marine conservationist at the American Museum of Natural History, believes that orcas are smart and would not do such a thing purely on impulse. "This was premeditated," he told the Associated Press.

We will never know exactly what was going on in Tilly's mind, but we do know that he has been in captivity since he was about two years old – he was captured off the coast of Iceland in 1983. Orcas are social mammals, and he would have been living with his mother and other relatives in a pod. It is reasonable to suppose that the sudden separation was traumatic for Tilly.

Moreover, the degree of confinement in an aquarium is extreme, for no tank, no matter how large, can come close to meeting the needs of animals who spend their lives in social groups swimming long distances in the ocean. Joyce Tischler, of the Animal Legal Defense Fund, described keeping a six-tonne orca in Sea World's tanks as akin to keeping a human in a bathtub for his entire life. David Phillips, director of the International Marine Mammal Project for the Earth Island Institute, which led the efforts to rehabilitate the orca Keiko – made famous by the movie Free Willy – said: "Orcas deserve a better fate than living in cramped pools."

But if we are pointing the finger at SeaWorld for what it does to its captive animals, we should also look more broadly at the way we confine performing animals. In most countries, it is possible to visit zoos and see bored animals pacing back and forth in cages, with nothing to do but wait for the next meal.

Circuses are even worse places for animals. Their living conditions are deplorable, especially in travelling circuses where cages have to be small so that they can go on the road. Training animals to perform tricks often involves starvation and cruelty. Undercover investigations have repeatedly shown animals being beaten and given electric shocks.

Several countries – among them Austria, Costa Rica, Denmark, Finland, India, Israel and Sweden – ban or severely restrict the use of wild animals in circuses. In Brazil, a movement to ban wild animals from circuses started after hungry lions managed to grab and devour a small boy.

Several major cities and many local governments around the world do not permit circuses with wild animals. Last year, Bolivia became the first country to ban all animals, wild or domestic, from circuses. That decision followed an undercover investigation by Animal Defenders International, which exposed shocking abuse of circus animals. Now the British government is holding a public online consultation on the use of animals in circuses. Many hope it will be a first step towards a ban.

Attempts to defend amusement parks and circuses on the grounds that they "educate" people about animals should not be taken seriously. Such enterprises are part of the commercial entertainment industry. The most important lesson they teach impressionable young minds is that it is acceptable to keep animals in captivity for human amusement. That is the opposite of the ethical attitude to animals that we should be seeking to impart to children.

Nor should we be swayed by the argument that circuses provide employment. The human slave trade also provided employment, but that was no argument for perpetuating it. In any case, in many countries that have restrictions or bans on circuses with animals, human-only circuses have flourished.

There is no excuse for keeping wild animals in amusement parks or circuses. Until our governments take action, we should avoid supporting places where captive wild animals perform for our amusement. If the public will not pay to see them, the businesses that profit from keeping animals captive will not be able to continue. When our children ask us to take them to the circus, we should find out if the circus uses wild animals. If it does, we should explain to our children why we will not take them there, and offer to take them to a circus that does not.

• Copyright: Project Syndicate, 2010