David Goodall, 104, an accomplished Australian scientist, isn’t terminally ill, but he wants to die.
Mr. Goodall says his quality of life has deteriorated so badly that he has no reason to live, and he would like to end his life through assisted suicide. But he can’t do it in his own country, where the practice is banned.
So on Wednesday, he took what was expected to be his last flight, bound for Europe, to accomplish his goal — and his quest has renewed a debate in Australia about the right to end one’s life and what role others should play.
Mr. Goodall left his home in Perth to fly to an assisted-dying agency in Basel, Switzerland, a country where assisted suicide has been allowed for decades.
Though nations like Belgium, Canada, Colombia, Luxembourg and the Netherlands (along with some American states and the District of Columbia) permit euthanasia or assisted suicide, Switzerland is the only country with centers that offer assisted-suicide services to foreigners if the person assisting acts unselfishly.
When Mr. Goodall, a renowned ecologist, turned 104 in April he said, “I greatly regret having reached that age.”
Asked if he was happy, he responded: “I’m not happy. I want to die. It’s not sad particularly. What is sad is if one is prevented.”
At the airport on Wednesday, Mr. Goodall expressed regret at having to leave Australia to fulfill his wish, telling reporters, “I’m sorry that I have to travel to Switzerland in order to execute it.”
Sitting in a wheelchair, he added: “I’ve lived quite a good life until recently. The last year has been less satisfactory for me because I couldn’t do things.”
Philip Nitschke, a right-to-die activist and author whose organization, Exit International, helped Mr. Goodall pay for his plane ticket in business class through a GoFundMe campaign, said on Twitter: “Australia will not allow him to access the drugs to achieve this, but Switzerland does.”
He added, “The world is changing but Australia lags badly.”
Assisted suicide has been banned in Australia for decades. In 1995, the Northern Territory became the first legislature in the world to pass a law for voluntary euthanasia, but it was overturned by the national Parliament in 1997.
Victoria State passed a bill in 2017 to legalize assisted suicide, but it could not benefit Mr. Goodall. Set to go into effect in June 2019, it will apply only to terminally ill patients who are of sound mind and who have a life expectancy of no more than six months.
The Australian Medical Association is generally strongly opposed to assisted dying. “Doctors are not trained to kill people. It is deep within our ethics, deep within our training that that’s not appropriate,” its president, Dr. Michael Gannon, said during a legislative debate in Victoria last year.
“Not every doctor agrees with that,” he allowed.
Indeed, a survey of the A.M.A. found that four in 10 members supported right-to-die policies.
Mr. Goodall, who was born in Britain, began his scientific career at Imperial College in London, according to Exit International. At the University of Melbourne, he was a senior lecturer and held positions at what is now the University of Ghana; the University of Reading, England; the University of California; and Utah State University, among other institutions.
Having earned three doctorates, he worked with the Commonwealth Scientific and Industrial Research Organization, an independent Australian government agency, until his semiretirement in 1979. He was awarded the Order of Australia at age 101.
Mr. Goodall lived alone in his later years, though he has children and several grandchildren. Most of his friends have died. But he did his own shopping, read Shakespeare and presented poetry to a group.
Until 2016, he worked as an honorary research associate at the Center for Ecosystem Management at Edith Cowan University in Perth, taking two buses and a train to get to his office four days a week.
When he was 102 and called Australia’s oldest working scientist, the university stirred up a tempest by asking Mr. Goodall to vacate his office on the grounds that he was too frail and a safety risk to himself. He challenged the decision, but he moved closer to home to continue working.
His world became smaller, however, as he was forced to give up driving and performing in the theater, Carol O’Neill, a friend and a representative of Exit International, told journalists.
“It was just the beginning of the end,” she said.
Then, last month, he fell in his one-bedroom apartment and was not found for two days. Doctors ordered him not to use public transport or even to cross the road by himself. His physical condition deteriorated.
His daughter, Karen Goodall-Smith, a clinical psychologist, told ABC at his party that his work had probably been keeping him alive. “His work is his hobby, as well as his passion,” she said, “and without his work, I don’t think that there would be a purpose for him any more.”
Ms. Goodall-Smith added, according to Exit: “He has no control over his life, over his body, over his eyesight. He has lived a really good 104 years. Whatever happens, whatever choices are made, they’re up to him.”
Mr. Goodall is adamant. “One should be free to use the rest of one’s life as one chooses,” he has said. “If one chooses to kill oneself, then that’s fair enough. I don’t think anyone else should interfere.”