World Population 
DISCUSSION 
Klein: ‘The ovulation-inhibiting compounds that Dr. Pincus 
has talked about are mainly progestins. The very first function 
that was ascribed to the corpus luteum (which produces the 
natural progestins) was the inhibition of ovulation. This was 
suggested by Prenant, and by Beard as long ago as 1898. 
Professor Parkes has told us that we are extrapolationists. 
This is a very good idea, but I am afraid that within it lies the 
main danger of all we are to discuss here. Within what limits 
can results obtained on animals be transferred to human 
beings? ‘This is a question which can be considered on two 
levels: first, on the technical and biological level, and then on 
what we should call the normative level. We ought to be very 
careful about the distinction between what we call descriptive 
sciences and normative sciences. I feel that this distinction is 
not being made. Dr. Pincus said that it is desirable for us to 
control reproduction—not only in number, but perhaps also in 
quality. The word “‘desirable’’ shows that there is a definite 
human plan. From the technical point of view there is not 
much difficulty now in controlling reproduction. As Dr. 
Pincus has shown, there are a number of substances which can 
interfere with reproduction, in either the male or the female, 
and Dr. Parkes has indicated that it will soon be possible to 
control the ratio of the sexes. But is it desirable? And, if so, 
how can this be done in a human way? 
I should like to add here a brief point from my own exper- 
ience. Sometimes outside the professional field something 
happens in the life of a man which completely changes his 
way of thinking, and such a thing happened to me. I spent a 
whole year in the worst Nazi concentration camp, Auschwitz 
100 
