Madam, - Prof Gerry Whyte, (June 29th) quotes Prof Peter Singer in refutation of Dr Keith Lockitch's defence of stem cell research, on the basis that the cluster of cells destroyed in the process of such research is a potential, rather than an actual, human being. However, Prof Singer's quoted conclusion that "liberals" cannot demonstrate that the foetus is simply a potential human being relates - as Prof Whyte himself indicates - to "the stage of development when most abortions take place".
This is, of course, a much later stage than that at which blastocysts are destroyed in the process of stem cell research.
What Prof Whyte does not quote is Prof Singer's conclusions that abortion is "much less serious" than killing human beings and that the destroying of blastocysts is even less ethically problematic than abortion. - Yours, etc,
SÉ D'ALTON, Palmerston Road, Dublin 6
Madam, - The ethics surrounding stem cell research is complex and subtle, but Dr Keith Lockitch does nothing to clarify the debate in his use of a metaphor (June 27th) comparing an embryo with a canvas.
A canvas is quite unlike an embryo. Left in situ, a canvas will not spontaneously absorb paint and become something else, for it is not alive.
Thus, whether you choose to label an embryo "human" or a "mass of undifferentiated cells" is dancing on the head of a pin. It is an evasion to fail to address the matter of state-transforming process inherent in metabolically active entities.
The core of the ethics issue is whether it is justifiable to cause processes in a cell cluster to cease that might otherwise in favourable conditions become something we would designate human.
If that wholly mechanistic potential did not exist within the cluster of cells we call an embryo, then there would be no issue of ethics worth debating. - Yours, etc.
STEPHEN BARRETT, De Vesci Hill Abbeyleix, Co Laois.