Some members sitting in the Northern Ireland Assembly had done terrible things in the past, Mr David Trimble said on being proposed as First Minister. But the UUP had acknowledged that people could change, and had never said that because people had a past they could not have a future.
"There are people who have done terrible things, who have not been made amenable for them, and they are here . . . We are not saying, nor have we ever said that, simply because someone has a past, they can't have a future. We have always acknowledged the possibility that people can change. I think that's fundamental to your outlook to society," the UUP leader said.
Mr Trimble said that not all those who had done terrible things were sitting "in one corner of the room". He was responding to repeated questions from members of the DUP and the UK Unionist Party on the issue of whether he would sit in government with members of Sinn Fein.
To barracking from anti-agreement unionists, Mr Trimble said the questions were not put "in the sense of genuine inquiry", but as "a cheap, political stunt".
He said the answer to the question could be found in the manifesto of the Ulster Unionist Party, which said that "before any terrorist organisation and/or its political wing can benefit from the proposals contained in the agreement on the release of terrorist prisoners and the holding of ministerial office, a commitment to exclusively peaceful and non-violent means must be established".
He said the UUP would be using "objective, meaningful and viable criteria" to assess this, and these were set out in the manifesto.
Mr Trimble said his party would not sit in government with "unreconstructed terrorists". The important thing that had to be established was a commitment to the democratic process.
The UUP leader said he hoped Northern Ireland was coming out of a morass, and he knew such an opportunity existed. "I know that there is a great thing to be gained by all sections of this community, and I am conscious, as Seamus [Mallon] is, of the responsibilities that will come to us. I am conscious of the obligations we have to all of society.
"I know that it is not going to be easy . . . but we have started on our journey. We have started on the long march, and we are determined to continue that, despite the difficulties that present themselves. We are determined to succeed for the benefit of all of society, and it is that opportunity that must not be discarded."
Mr Trimble was repeatedly heckled by members of the DUP.
Earlier the SDLP deputy leader, Mr Mallon, in accepting his nomination as Deputy First Minister, said people in the Assembly shared "an absolute conviction that now, at the end of this century, we are going to change the face of life in the North of Ireland. We are going together to create a new quality of life. We are going to tackle problems together, all of us.
"There will be no exclusions in this new arrangement. There will be no exclusion of anyone who has that sense of hope, that sense of commitment, and that sense of belief that it is not an option to seek for change. It is an imperative on this generation to make it," Mr Mallon said.
He said he looked forward to working with Mr Trimble, whom he had known for a long time. "We don't always agree, and there will be times when we disagree, but we will disagree face to face, and what disagreements we have we will sort out, face to face."
In a humorous note that drew smiles from Mr Trimble, referring to the persistent attacks on him by anti-agreement unionists, Mr Mallon said he was sure the Ulster Unionist leader's back was "sore enough at the present time that he wouldn't appreciate it any other way".
Mr Mallon said that he, along with the UUP leader, would do everything in their power "to help every member effect those changes that we have agreed and open up, by doing that, a new vision and a new imagination for a new century".
The SDLP deputy leader was then asked by Mr Cedric Wilson of the UKUP what his exact position was on the decommissioning of paramilitary weapons. Mr Mallon replied that he wanted to see decommissioning as soon as possible.
"Yes, I think it has to be done. Yes, I think those who hold arms and are associated with those who hold arms can help, and they can help the process that we are all part of. I cannot be any clearer than that."
Mr Mallon said everybody could air grievances or engage in "whataboutery", and could point out what was done to their communities.
"We can all point out that the other fellow was always wrong. This time let all the fellows, and girls, join together in ensuring that what we do is going to be the right thing for the people - and the only people who count - the people on this island, especially those by whom we are elected in Northern Ireland."
Mr Mallon said there would be difficulties ahead, and those difficulties were shared by everybody. He felt a sense of humility and "an awesome sense of responsibility". The future would be based on the agreement, consent, equality and justice.
"I stand by the agreement that we all signed, not the bits I like, but the bits I like and the bits I don't like," declared Mr Mallon, whose speech drew the loudest applause of the day.