Ross Douthat, as well as many other reactionary writers, thinks a low birth rate is strong evidence of decadence. It shows that a society no longer has confidence in itself and its mission, and just wants to live for today. Decline inevitably follows.
But if that is the case, how do we account for the extremely low Chinese birth rate? Does anyone seriously believe that China is also decadent?
The fact is that low birth rates are tied to regulations, the size of the welfare state, the cost of living, and the character of the economy. They don’t really have much to do with decadence, however you may define the term.