When it comes to repro­duc­tion, are indi­vid­u­als who strive only for per­sonal gain—as Adam Smith stated in The Wealth of Nations—“led by an invis­i­ble hand […] to pro­mote the pub­lic interest”?

In The Tragedy of the Com­mons, ecol­o­gist Gar­rett Hardin sug­gested not and called for fur­ther gov­ern­ment inter­ven­tion to help con­trol ris­ing populations.

Recent stud­ies, how­ever, are sug­gest­ing that the cur­rent laissez-faire approach to repro­duc­tion in devel­oped and eco­nom­i­cally ‘free’ coun­tries does lead to an opti­mal pop­u­la­tion. (As always, there are caveats.)

In 2002, Seth Nor­ton, a busi­ness eco­nom­ics pro­fes­sor at Wheaton Col­lege in Illi­nois, pub­lished a remark­ably inter­est­ing study on the inverse rela­tion­ship between pros­per­ity and fer­til­ity. Nor­ton com­pared fer­til­ity rates of over 100 coun­tries with their index rank­ings for eco­nomic free­dom and another index for the rule of law. “Fer­til­ity rate is high­est for those coun­tries that have lit­tle eco­nomic free­dom and lit­tle respect for the rule of law,” wrote Nor­ton. “The rela­tion­ship is a pow­er­ful one. Fer­til­ity rates are more than twice as high in coun­tries with low lev­els of eco­nomic free­dom and the rule of law com­pared to coun­tries with high lev­els of those measures.”

Nor­ton found that the fer­til­ity rate in coun­tries that ranked low on eco­nomic free­dom aver­aged 4.27 chil­dren per woman while coun­tries with high eco­nomic free­dom rank­ings had an aver­age fer­til­ity rate of 1.82 chil­dren per woman. His results for the rule of law were sim­i­lar; fer­til­ity rates in coun­tries with low respect for the rule of law aver­aged 4.16 whereas coun­tries with high respect for the rule of law had fer­til­ity rates aver­ag­ing 1.55.