Pat Rattigan's argument (Letters, July 16) would not pass muster in a sixth-form debate.

What is he saying, that vivisection research has resulted in a reduction in human health? Take any developing country as a case in point.

Are diseases rife in those countries because pharmaceuticals are more or less freely available than in Western countries? Does Rattigan consider anti-retroviral drugs to be the cause of Aids rather than its relief?

The reason some 40 per cent of people in the UK will develop cancer is that they live long enough to succumb to it eventually. Many of the conditions listed, including some cancers, are lifestyle-related. Modern medicine warns against unhealthy lifestyles.

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The main crime of Western society is to price medicines out of the reach of those in the developing world.

It is laughably easy to demonstrate the imbecility of the anti-vivisectionists' argument. Every letter they publish makes the case for vivisection.

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David McAlpine
Department of physiology
University College London