Should the world adopt a one-child policy?

China adopted one-child policy for multiple decades. Some speak of overpopulation and the related pressure on ecosystems. Should the world adopt a one-child policy, limiting each pair to have at most one child, or in rare exceptions two children?

There is a broader question: Should we aim to reduce the Earth population?. The present question is narrower: it asks about a particular method. The kinds of arguments most interesting are going to be those that pertain to the particular method, namely top-down state-coercive one-child policy; these are going to assume that we do need to reduce the world population. Since, if we don't, then of course we do not need one-child policy either.

Arguments for

 * Voluntary descendant reduction will not work in the middle run: the subcultures that advocate for as many children as possible are going to outpopulate the subcultures that voluntarily restrict themselves. There is a similar Darwinian principle on the genetic level: the genes coding for higher fertility are going to prevail in the pool. The only sustainable solution is a top-down policy.

Arguments against

 * It is a human right to have as many children as one wishes.
 * That is not obvious. The principle that each should feel free to have as many children as possible seems, when adopted systematically, lead to morally undesirable outcomes: depletion of resources, destruction of natural heritage including species and a sharp collapse of human population. Thus, such a position does not seem moral.
 * It is very clearly obvious. Just like it is our right to freedom, free speech, and the ability to practice any religion you want, then it should be a right to have as many kids as you want. As long as you are fully taking care of them, there should be relevant no reason to restrict it. If it becomes detrimental to the environment or society, we can advocate that people don’t do it, not force people not to, just like we do with issues like fossil fuels.
 * Such a policy in inhumane.
 * A sharp population collapse resulting from resource exhaustion or other disruption of the interdependent network of the modern civilization is more inhumane, leading to mass death by starvation. And voluntary reduction will not work, as per the argument for.
 * It might not be necessary when a population is considered as a whole. e.g. imagine 10 couples: 5 have no children, 2 have 1 each, 1 has 2 each, 1 has 6—a total of 10 children ÷ 10 couples = 1 child per couple.