Logic does not demand this. There is no inconsistency in claiming that what is right or permissible in certain circumstances is wrong in others.
The claim that voluntary assisted suicide will lead to patients being killed against their will is pure fantasy on the part of Mr Lucas and those like him.
We have voluntary marriage in this country – but there has been no lobbying for compulsory marriage. People may in certain circumstances opt for abortion – but there is no pressure for compulsory abortions.
Adults can opt for sexual relationships in this country – but there is no inevitable movement towards legalising rape.
Indeed, the sphere of sexual ethics affords an excellent lesson here.
In recent years we have seen increasing endeavour and refinement in ensuring that consent to sexual relations is fully and genuinely given.
This has included a change to the legal definition of “rape”. One may expect a similar emphasis on ensuring that assisted suicide is genuinely the choice of the suffering patient.
Mr Lucas should realise that his opposition to assisted suicide in any circumstances whatsoever means accepting that some people must be condemned to pointless and unassuageable suffering in order (as he fantasises) to prevent others from being killed against their will.
This is a morally dubious position comparable to the crude utilitarian justification of the evil of torture in order, supposedly, to benefit others.