Is it actually ethical for medical science to try to develop cures for all diseases? Isn't disease helping to keep our population in check? If our population grows too much and depletes our resources, wouldn't wars over resources be the greater harm incurred?
If humans continue to reproduce at current rates, there is good reason for thinking that population growth will eventually be (if it already isn't) harmful to the well-being of humans and non-humans (though not only because of possible resource wars--there may be other harms related to unchecked population growth besides these, e.g., increased suffering due to malnutrition, crowding, pollution, habitat destruction, etc.) However, there is little reason for thinking that stopping the curing (or preventing) of diseases by medical science is the only or the most morally attractive way of limiting population growth and avoiding problems due to such growth. Many humans already limit population growth quite safely and effectively through various methods of birth control. Improvements in education, increased access to birth control and family planning services, and changes in incentives for having large families, can provide more morally attractive ways to avoid harms due to population growth.