Anti-Malthusians are more concerned with a population shrinkage than overpopulation. They believe that there will be three different stages in a demographic transition. First the population will become stable because of both high growth and birth rates. Next the population will skyrocket. Finally, the growth rates will lower to become the same as the death rates. It is all part of the cycle they believe, but a population shrinkage is the opposite of what they are looking for.
