MR Thomas Bromley writes again (You Say, December 29) on the use of animals in medical research.

Regrettably, his letter ignores questions raised in earlier correspondence. It is, in essence, an appeal to "Authority" whose views we are meant to accept unquestioningly.

I think that events over the past few years have convinced most people of the need to adopt a healthy scepticism towards arguments of this nature.

Mr Bromley refers to medicines "validated through research using animals" but does not explain how such "validated" medicines can sometimes cause disasters.

In order to justify the usefulness of their work, researchers seek to emphasise similarities between humans and animals. But to defend it ethically, they must emphasise the difference. Surely a case of trying to have it both ways!

STAN BROWN, Worcester.