Would China's Population Be Even Smaller Had There Been No One-Child Policy?

For many years, the accepted wisdom in the world has been that China's one-child policy was the reason for the rapid decline in that country's birthrate. In the last several editions of my Population text, I have questioned that assumption, noting the incredible similarity between the fertility trajectories in China and its geographically and culturally close neighbor Taiwan (indeed, close enough that China claims it as its own). Here is my graph from the 13th edition of Population, which will be out very soon:

Given my history with this issue, I was very interested to read a paper by Stuart Gietel-Basten and his colleagues that was published just this week in PLOS/ONE: "Assessing the impact of the “one-child policy” in China: A synthetic control approach." They use a set of sophisticated demographic techniques to make the case that fertility might have declined even more quickly in the absence of the one-child policy--albeit in the continued presence of the wan xi shao ("later, longer, fewer") campaign launched a few years prior to the one-child policy. Here is their summary graph:

The implication of their findings is, of course, that a faster decline in fertility would actually have produced fewer people in China than there are now. Their results also help to explain why fertility has not risen in China despite the official end of the one-child policy. This is an important article regarding population policy, and I strongly recommend it to you.