The former Archbishop of Canterbury, Baron Williams of Oystermouth, and Hebrew scholar Irene Lancaster, discuss the implications of assisted suicide being made legal if Kim Leadbeater's bill succeeds, and why they are against this.

IL: Before we start this dialogue I should point out that, given the recent second reading of the Assisted Dying Bill in the Commons, I have today reregistered with a young GP at a new medical practice who I know shares our view on the sanctity of life and won't be tempted to assist my own death ostensibly for my 'own good', but in practice against my will. I also encourage everyone to update provision for end of life care.

We are very lucky in this country to have experienced the chief rabbinate of Lord Immanuel Jakobovits (1921-99) who officiated in this post from 1967 to 1991 and had huge influence on our own community as well as on the public at large.

Lord Jakobovits' seminal book 'Jewish Medical Ethics' (1959/75) is still relevant today and continues to be an invaluable source of science and wisdom combined. In addition Lord Jakobivits encouraged scientific endeavour, and especially space exploration, much to the delight of the Astronomer Royal, Heather Couper.

This is what Lord Jakobivits had to say about life: 'The value of human life is infinite and beyond measure ... Any part of life - even if only an hour or a second - is of precisely the same worth as seventy years of it, just as any fraction of infinity, being indivisible, remains infinite.'

To sum up, his motto was the Deuteronomic 'Choose life'. This is the Jewish way and has always been. Where others choose death, observant Jews have chosen life.

This is not to diminish the suffering of people in pain. However, this is why the way forward is an increase in funding of palliative care. To cross that line, to treat a patient's suffering by ending the patient, is actually deathcare, not healthcare. It is tantamount to murder, which is against Halakha (Jewish law). In Jewish law we are forbidden to murder another human being, which is actually what 'assisted dying' is, as Orwell would point out!

RW: This is the key point, I think. For a person of religious commitment, there is no human circumstance in which it's impossible to turn to God and to act in a way that honours God and bears witness to God in some fashion. As soon as you say there are specified conditions in which this is no longer possible, you're implying that our humanity in effect disappears, or is radically undermined by some conditions in such a way that it loses its full dignity.

And that's a dangerous door to open - as so many disability campaigners who have expressed their concern about this legislation are pointing out. Some lives are being judged as less genuinely human than others.

IL: Tragically, however, this rational Jewish stance towards life and death, living and dying and treating the weak, old, sick and vulnerable with dignity as G-d's creatures, has been dismissed by a number of lawyers and members of the chattering classes as 'merely religion' and therefore as 'irrational', an infantile pastime, irrelevant to the serious business of carrying out state murder.

RW: It's sometimes a difficult point in debate. As I've said more than once in arguing the case, of course my opposition is grounded in my Christian commitment. But a Christian, just like a Jew, will want to say, 'If this is the will of the Creator, we should expect that there are sound arguments against assisted dying that can be based on practical considerations as well as the fundamental religious perspective.'

So we need to fill out the 'religious' case with the many concerns about practical challenges and risks that are being discussed extensively in the debate. These are issues about the risks of open or implied coercion, the radical change in the relation between physician and patient, the temptation to see assisted dying as a neater and cheaper option than the expense of palliative care, and so on.

Some of my friends in Canada have pointed out to me that over there, where they have a fairly 'permissive' assisted dying regime (MAID, 'Medical Assistance in Dying'), the number of people in some economically deprived areas who opt for physician-assisted suicide is much higher than in the rest of the population.

That ought to make us stop and think. Is this going to turn out to be another turn of the screw in economic deprivation and disadvantage? A default-setting assumption that assisted dying is for those who can't afford or can't articulate an alternative? We're never just talking about decisions in an economic and social vacuum. And that's one reason why it won't do to set up an opposition between 'irrational' religious apologists and 'detached' scientific commentators.

IL: For the fact is that some of our greatest Jewish rabbis, Bible commentators and Talmud scholars were like our late contemporary, Lord Jacobovits, medical doctors and scientists, as well as communal leaders. These include the mediaeval giants, Maimonides (Rambam) and Nachmanides (Ramban).

As well as Lord Jacobovits, in our own day, Rabbi Joseph Soloveitchik (1903-93), affectionately known as the Rav, emphasized that Judaism is based on the scientific approach, and is neither a faith nor irrational.

He further emphasizes that Judaism is 'this-worldly, here-and-now grounding', as opposed to religious approaches that focus on the transcendent realm. For him Judaism is an entirely rational, cognitive process which utilizes the analogy of mathematical, natural sciences.

RW: I think that Christian participants in the debate would say very much the same. Christianity has sometimes given the impression that it is excessively focused on the heavenly realm; but in fact there is another dimension to it, which you can see in Jesus' own emphasis on every day being a day when you can respond to God with your full being, without trying to map out and control every possible future problem.

And many theologians across the centuries have stressed that the material world we inhabit is a place where we can see God at work in daily things. The Christian sacraments express the idea that this world in its physical reality is also where God communicates with us.

IL: Now Rabbi Shlomo Brody, an Israeli expert on medical ethics, has just sent me a link to his organization Ematai, which includes his recent op-ed for the UK-based Jewish Chronicle on the current proposed bill, as well as offering positive suggestions on how we can help the terminally ill and dying through palliative care.

RW: The elephant in the room in our recent debate has been the deep concern that the presence of a less expensive alternative to end-of-life care by way of palliative medicine is bound to put pressure on an already pressurized health system, and also on the funding of research in palliative care.

Think it through: investing in palliative care research and provision means leaving open a better choice for more people. Cutting back on this means that, if research and provision are squeezed, the choice of not accepting assisted dying will become much harder. There will be less incentive to go on reducing the number of unmanageably painful conditions by sustained research; there will always be the consciousness that a sufferer is a drain on scarce funds.

As the debate has gone on, it has been instructive to see at least some commentators in favour of a change in the law becoming more open about this. Well yes, they say, perhaps it's time to come clean about some people being an unnecessary burden on public resources.

And that's where I believe a line is crossed. That's where two highly problematic things emerge. One is that lives are being assessed on a financial basis. The other is that pressure increases on those who don't want to die.

Kathryn Mannix, a palliative specialist, in her excellent book With the End in Mind, describes the case of someone emigrating from the Netherlands to the UK after a very bad experience with a medical system that - gently but persistently - pushed him again and again on whether he wouldn't be better off opting for assisted dying.

And despite the insistence of campaigners that the proposed legislation would have robust safeguards and - for example - protections for young people, I don't see any careful statement of the evidence from other jurisdictions that such safeguards are stable.

We have seen in some European instances how the pressure to extend definitions to include mental distress and to accommodate the wishes of younger people shifts the goalposts. I don't know, but I suspect that many of the general public who support the legislation aren't fully aware of some of these complications.

IL: In his biography by Tom Baldwin, the present PM is quoted as stating that he promised an aging BBC personality that he would bring forward this bill. This is not the best basis on which to introduce a life-changing law that will have unforeseen repercussions for our children and grandchildren. We have seen what has happened already in Canada, the Netherlands, Belgium and a number of American states. A desire to die becomes a duty to die.

Relatively young people are being asked to give up their lives in Canada rather than undergo routine, minor surgery. I don't know about you, but this seems to be very similar to the methods used in Nazi Germany to hasten the death of the weak, feeble, infirm, old and handicapped. Later, this same approach was used on the Jews en masse, who were also regarded as being essentially defective. What do you think of this state of affairs?

RW: That phrase 'essentially defective' is important. As I said earlier, one of the risks is that we end up in effect defining certain conditions as 'defective'; if you suffer in this way, the governing assumption is that you ought to be ready to die. Now of course the legislation is supposed to be about increasing choice, not about the state's power to take life.

But the question that still haunts me is the risk of changing the ground rules in a way that gives some people the right to decide what counts or what should count as a conditon that makes life not worth living. Supporters of the bill argue that 'religious zealots' are trying to limit other people's freedom; I think that the argument can be made the other way around as well.

IL: In the Spectator of 21 September, the writer Matthew Hall recounts the physician-assisted death euthanasia of his Canadian aunt, aged 72. MAiD, which you mentioned above, is now the fifth most common cause of death of Canada and may soon extend to the mentally ill, as in Nazi Germany. What is being done in Canada is still regarded as murder-suicide here. But maybe not for much longer.

Matthew Hall recounts: 'My aunt's body was zipped into a black nylon bag and trolleyed out into a van.... Dial-a-death proved, even for someone as implacably opposed to euthanasia as I am, seductive. It offered a small glimpse into how evil works: remove the sacred boundary and it becomes commonplace. Easily digestible. The norm.'

RW: 'The norm'. There's the heart of it. Like many people in the medical and clerical world - and plenty more non-professionals like yourself who have simply worked with or sat alongside people with appalling terminal conditions - I'm not unfamiliar with terrible and heartbreaking situations, and I don't for a moment belittle the awfulness of some extreme cases, or the kind intentions of many who want to see a change in the law.

But assisted dying advocates will sometimes speak as though religious believers were determined to inflict maximal pain on sufferers and to keep them alive at all costs. This is nonsense, of course. We are all familar with instances of physicians taking steps that they know will in practice accelerate death as well as controlling pain.

Prolonging life at all costs is not a religious or ethical priority. But the base line we have hitherto held is that there is a difference between good and compassionate medical practice as we have known it - increasing sedation, withdrawing certain supports and so on - and actually initiating a fresh process whose primary aim is to end life. That is the new norm and I don't think its implications have been fully weighed.