Peter Singer's 1975 book Animal Liberation  has frequently been called "the bible of the animal rights movement" and its publisher calls the work "the book that started a revolution."
In an era before most people knew what a "vegan" was, Singer argued for the basic rights of all animals to be respected and against the idea that human interests by definition come before those of other animals. Singer, an Australian philosopher who is a professor at Princeton University, is controversial for all kinds of views, but to animal rights activists and biomedical researchers, Animal Liberation has also been a work to define him.
So as word emerged in the last week that Singer had recently acknowledged the possibility that a research project involving animals could have been ethically justified, many were shocked, and advocates -- for and against research with animals -- scrambled to figure out what he said and what it meant.
It turns out that Singer did say that some experiments involving animals to benefit human health might be justified -- and he's on camera saying so. But he argued that his statement was defined in a way to be entirely consistent with Animal Liberation, and sets a very high bar (perhaps impossibly high) for research to meet his standards. Still, Singer is already being attacked by some in the animal rights movement -- and defenders of biomedical research say that the incident shows the contradictions in the animal rights movement.
Singer's comments came in a BBC documentary about the conflict between scientists at the University of Oxford and animal rights activists who have been trying to stop their work.
According to an account of the documentary in The Times of London,  which Singer has not disputed, Singer is shown in an exchange with Tipu Aziz, an Oxford neurosurgeon who has developed new treatments for Parkinson's disease, in part by giving Parkinson's to non-human primates for experiments. Aziz tells Singer that about 40,000 people have probably been helped by the research, and that about 100 monkeys were used to develop the treatment.
Singer then tells Aziz: "Well, I think if you put a case like that, clearly I would have to agree that was a justifiable experiment." Singer then goes on to say that as long as "there was no other way of discovering this knowledge," he could "see that as justifiable research."
Given the absolutist views of many animal rights activists -- namely that it is impossible to justify experiments with animals -- the quotes immediately had people talking about whether Singer had changed his views. The reaction from some animal rights groups has been swift.
A British animal rights group that has been fighting Aziz and his research published an update denying that Singer had ever been a leading figure in the movement (it might want to check PETA's Web site  to verify that Singer has been considered its hero). The British Web site, Arkangel for Animal Liberation,  published the following: "Peter Singer seems to have fallen foul of the lies propagated by the vivisectionists and many in the animal rights movement are now expressing their disgust," adding that "the man talks rubbish and the sooner the notion that he has any place in the modern animal rights movement is dispelled the better."
Singer, reached by e-mail, sent two letters that he has sent to British publications that have written about his statements in the documentary. In the letters, he states that it is incorrect to view his quotes in the documentary as representing a change in his position. He writes that he has never said "that no experiments on animals could ever be justified," and goes on to explain: "My position has always been that whether an act is right or wrong depends on its consequences. I do insist, however, that the interests of animals count among those consequences, and that we cannot justify speciesism, which I define as giving less weight to the interests of nonhuman animals than we give to the similar interests of human beings."
As a philosopher, Singer is a utilitarian and his explanation is consistent with that school of thought's approach about looking for the maximum good by weighing the impact on various actors (although many utilitarians would apply that view to all human actors, but not all animal actors).
As for Aziz's research, Singer writes while it is possible that his studies are ethical, he still believes in a question he first posed in Animal Liberation: "I suggested that a test for whether a proposed experiment on animals is justifiable is whether the experimenter would be prepared to carry out the experiment on human beings at a similar mental level -- say, those born with irreversible brain damage. If Professor Aziz is not prepared to say that he would think such experiments justifiable, his willingness to use animals is based on a prejudice against giving their interests the same weight as he gives to the interests of members of our own species."
In his response to the BBC documentary, Singer also writes that "whether or not the occasional experiment on animals is defensible, I remain opposed to the institutional practice of using animals in research, because, despite some improvements over the past 30 years, that practice still fails to give equal consideration to the interests of animals."
Via e-mail, Aziz said that he thought Singer's comments -- in the documentary and later -- were "very significant" because research with animals is in fact necessary. "If one looks for animal contribution and why it is and was essential one would have to review all of medical history," he said.
Frankie Trull, president of the Foundation for Biomedical Research, which supports the use of animals in research and spars with animal rights groups, was not surprised to hear that Singer wouldn't in fact be applying to join her organization. But she said that the debate over his statements was an important one.
Many animal rights supporters "never understood what he was saying," Trull said.
But Singer provided an intellectual basis for the animal rights movement, she said. The hostility of the animal rights movement to real debate is clear by the way Singer is being treated, Trull said. Likewise, she said, Singer's ideas are being exposed for their own flaws.
Trull noted that Singer qualified his support for Aziz's research by saying that it depended on the animal experiments being necessary. Trull said that not only have animal rights supporters been able to demonstrate otherwise, but they have never offered scientifically valid and humane ways to do many kinds of research. And Trull noted that, following the horror of many at the Nazis experimentation on humans, the Nuremberg Code specifically called for research with animals prior to human studies. Scientists like Aziz aren't doing research with animals based on some whim or hunch, but based on a document embraced worldwide, Trull said.
The animal rights movement "sounds great," Trull said, because "we all love animals." But as even Singer seemed for a moment to acknowledge, she said: "Disease is ugly and cruel and science has to use the tools that are available."