And it’s true: If you approve zero drugs, it’s 100 percent guaranteed you will approve no harmful drugs. You’ll also approve no helpful drugs. As we learn more and more about the human genome, it’s become more clear that what is a lifesaver for many might be a death sentence for a few. Most people can eat peanuts; a relative few of us cannot. The Nestor approach would be to ban peanuts for everyone to prevent anyone from being harmed.

That argument works better for peanuts than it does for new medicines. After all, peanuts rarely save anyone’s life. Drugs, on the other hand, have the potential to work miracles for some patients. Nestor’s tale has gained wide currency as an allegory about the shortcomings of the FDA and the drug industry. But I keep thinking about it in the context of the gun debate in the wake of the Newtown, Conn., massacre.

For instance, it doesn’t take a genius to realize that James Holmes, the man charged in the shooting rampage at the Aurora, Colo., premiere of The Dark Night Rises, was at least somewhat inspired by the Batman movies. The evil freak dyed his hair orange and called himself “the Joker.”

But hundreds of millions of people saw one of the Batman movies. Let’s imagine those movies are 100 percent to blame for the Aurora shooting. Even under that ridiculous assumption, that would mean that something like 99.9999999 percent of consumers of those products were unharmed or unaffected.