Take gun control. I always accepted the libertarian position of minimum regulation in the sale and use of firearms because I placed guns under the beneficial rubric of minimal restrictions on individuals. Then I read the science on guns and homicides, suicides and accidental shootings (summarized in my May column) and realized that the freedom for me to swing my arms ends at your nose. The libertarian belief in the rule of law and a potent police and military to protect our rights won't work if the citizens of a nation are better armed but have no training and few restraints. Although the data to convince me that we need some gun-control measures were there all along, I had ignored them because they didn't fit my creed. In several recent debates with economist John R. Lott, Jr., author of More Guns, Less Crime, I saw a reflection of my former self in the cherry picking and data mining of studies to suit ideological convictions. We all do it, and when the science is complicated, the confirmation bias (a type of motivated reasoning) that directs the mind to seek and find confirming facts and ignore disconfirming evidence kicks in.
My libertarianism also once clouded my analysis of climate change. I was a longtime skeptic, mainly because it seemed to me that liberals were exaggerating the case forglobal warming as a kind of secular millenarianism—an environmental apocalypse requiring drastic government action to save us from doomsday through countless regulations that would handcuff the economy and restrain capitalism, which I hold to be the greatest enemy of poverty. Then I went to the primary scientific literature on climate and discovered that there is convergent evidence from multiple lines of inquiry that global warming is real and human-caused: temperatures increasing, glaciers melting, Arctic ice vanishing, Antarctic ice cap shrinking, sea-level rise corresponding with the amount of melting ice and thermal expansion, carbon dioxide touching the level of 400 parts per million (the highest in at least 800,000 years and the fastest increase ever), and the confirmed prediction that if anthropogenic global warming is real the stratosphere and upper troposphere should cool while the lower troposphere should warm, which is the case.