I’m all for universal background checks, tighter assault-weapon bans, limits on high-capacity magazines, and ambitious and well-funded gun-buyback programs. But unless we also find more effective ways to identify and treat people who are dangerously mentally ill, we’ll never stop tragedies like Newtown (or Aurora, or Tucson, or Virginia Tech).

There’s been lots of loose talk about Adam Lanza being “evil.” But, as Eagleman argues, science increasingly shows us that the biology of mental illness undermines traditional notions of culpability. Pretending otherwise only distracts us from taking steps to protect society, irrespective of how we judge dangerous people’s blameworthiness.

“Millions of 20-year-olds on this planet play video games, have divorced parents, are eccentric, have access to guns, and so on,” Eagleman wrote recently on his blog. “But Lanza tops the news because his actions are so exceptionally rare. Such abnormal decision-making unmasks abnormalities in brain function. To assume that prayer in schools and tough-love parenting is a meaningful solution to brain abnormalities [as some have suggested] is to miss the boat entirely.”

Characterizing Lanza and his ilk as “sick” rather than “evil” isn’t a way of medicalizing character flaws and excusing abhorrent behavior. It’s about letting science update the way we think about moral assessments that may not apply and do little to help us protect ourselves.