"I think [dialysis] frightened him, it scared him and for a number of months he refused the treatment and he was getting sicker and sicker," Cowley says. But unlike for many people suffering from potentially deadly medical conditions, that terrifying collapse was the start of drastic improvement – nudging him to start the treatment that keeps him alive today. His father's illness made Cowley, a committed Catholic, think more deeply about death than most 15-year-olds. And today, studying ethics as part of his arts and law degree at Sydney University, he wants other people to think about it too. After reading the philosopher Peter Singer's work in a course called practical ethics, Cowley, the president of the university's Catholic Society, said he was challenged to think about his own beliefs about euthanasia.

"I had the opportunity to examine his arguments and I was genuinely fascinated, although I intuitively disagreed with some of his conclusions," he says. "I think if euthanasia was legal in NSW, it's quite possible my father would have been a candidate." Cowley has organised a debate between Professor Singer and the new Archbishop of Sydney, Anthony Fisher, on whether euthanasia should be legalised. Their debate is to be hosted by Geraldine Doogue on Thursday, August 13. What started as a small debate at Sydney Uni has become so popular that organisers have been forced to shift to the Sydney Town Hall and organise live streaming after tickets sold out within three hours. For his part, Professor Singer, who holds professorships at Princeton and the University of Melbourne, said he was pleased the archbishop was willing to debate euthanasia with someone who didn't share his faith. And he was hopeful he might be able to change some minds. "Perhaps not the archbishop himself, but if you look at what's happened in regards to same-sex marriage there has been a huge shift in opinion," he says. "Why not this issue as well?"

He says someone who could be saved by treatment such as Cowley's father would not be eligible for euthanasia under a legalised system. "Although I do think there are cases where a person is suffering so much and the condition is incurable that I would accept the patient's decision to die," he says. The debate will be steamed live at euthanasiadebate.org from 6:30pm