Health and Disease 
DISCUSSION 
Medawar: I would like to thank the three speakers for being 
so amusing and pointed and cogent. Their papers were so full 
of combustible material that it is hardly necessary to open the 
discussion. I had one general reflection on Dr. Koprowski’s 
talk: we speak figuratively about the advancing front of medi- 
cine, but in point of fact there is no such thing. Medicine has 
no one front and it does not move forward as a whole. In the 
study of infectious diseases in advanced countries, I think it is 
true to say that the major task of medicine has already been 
accomplished. The force of mortality cannot fall below zero 
and the asymptotic character of its approach to zero is already 
perfectly obvious, anyhow up to, say, the fiftieth or sixtieth 
years of life. This is one of the great success stories of med- 
icine. At the other extreme, psychology, for example, has 
not yet reached the stage of removing the major impedi- 
ments to its own progress. The case against a psychological 
system of treatment such as psychoanalysis does not really rest 
on the fact that it is inefficacious—for that must be true of a 
great many forms of medical treatment—but on the fact that 
belief in psychoanalysis is an impediment to the discovery of the 
true causes of mental illness. 
Dr. Comfort was doubtful about using replacement—trans- 
plantation methods, for example—as a cure or palliative for 
sterile deterioration, because ageing is essentially due to a 
multiple failure of homoeostasis. I think that is altogether too 
vague a description of ageing, because all human afflictions and 
infections in fact could be described as failures of homoeostasis. 
I don’t think it will be possible to repudiate the idea of using 
replacement therapy until we have a theory of ageing, which 
we haven’t got at present. 
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