The problem facing modern society is that there is no agreement on what a human being is or what it is supposed to do, according to the Bishop of Limerick, Dr Donal Murray.
"We must have some kind of vision of who we are. That is how we exercise our freedom," he said.
Speaking last night at a conference on bioethics at the Institute of Technology, Carlow, he said it was very difficult to have an ethical discussion where there was no consensus. Lack of such consensus was why there was little meeting of minds in ethical discussion today where you have more heat than light.
"I believe the embryo is a human person. This is a crucial question. The whole of Christian tradition has held that everyone's life is deserving of respect," he said.
Prof Santiago Sia, dean of Carlow College, said ethics was not merely a matter of going by the book - it was much more than following an agreed way of behaving. He said that science was concerned with pushing out boundaries and what can be done whereas ethics was about what ought and ought not to be done.
"Our knowledge of what is ethical is not absolute, though there may be absolute moral principles," he said.
Prof Peter Whittaker of Lancaster University spoke about stem-cell research and the divisions of attitudes to it. He also said it could be unethical not to do things. He noted that the number of embryos stored across Europe was in six figures at this stage and said he felt it would be far more ethical to use these to save or improve life rather than have them destroyed.
Discussing genetically modified food, Trinity Professor of Genetics, Prof David McConnell, said the way Europe had treated scientists was unethical and immoral. He accused Europeans of "profound post-colonial arrogance" when it came to the use of GM in developing countries. "Our attitude is causing death and illness for no good reason," he said. There were 800 million starving people in the world today, with 45,000 dying of hunger every 24 hours, he said.
"We have got to introduce GM technology if we are to feed these people - that is the view of GM scientists."