- prohibit technology intended to escalate semi-automatic weapons' rates of fire to de facto automatic weapon levels,
- limit the capacity of magazines,
- intend to reduce firearm accidents, or
- intend to keep firearms out of the hands of young children and the minority of Americans with mental health issues inclining them towards violence, especially mental health issues related to paranoia or impulsive rage.
This brings us to another weak argument opposing firearms regulations such as a ban on high-capacity magazines or the imposition of background checks on buyers: Because the regulation will not altogether prevent criminal use of firearms, including in mass shootings, the regulation should be rejected.
This fallacy is anchored to a kind of "all or nothing" or "black and white" thinking. It's sometimes termed the Nirvana or "perfect solution" fallacy. It rejects a proposed solution to a problem because some part of the problem would persist after the solution is in place. It's a bit like objecting to laws requiring people to wear seat belts in cars because seat belts don't prevent whiplash—i.e., since seat belts can't prevent all injuries that might occur in a traffic accident, wearing them should not be mandatory.
The Nirvana argument against outlawing high-capacity magazines is generally that the shooter will still kill many people by using multiple lower-capacity magazines. The rebuttal is common sense itself: if it means even one less death than higher-capacity magazines would result in, it's worth it. Without higher-capacity magazines, the shooter will be fire fewer bullets per minute because they will have to change magazines more frequently! Each change takes time; each change is a moment when they aren't able to fire. This gives people more time to run away, to act, to live. What is more, the shooter is likely to be more encumbered if they're carrying multiple smaller magazines in numerous pockets or pouches.
Does outlawing high-capacity magazines make a hugely significant difference to, say, the lethality of a mass shooting? It depends on how you define significant. But it's likely to make at least a minor, slight difference in terms of reducing lethality. What is more, it's highly unlikely that the proposal—in this case outlawing high-capacity magazines—will have highly problematic consequences to those who own and use firearms legally and responsibly. A 30-round magazine is not an imperative for hunting or home defense.
The NRA will say otherwise. They will treat proposals for virtually any regulation as dire threats to the Second Amendment and the very existence of the notion of personal liberty.
(Image: Partial screen grab from the American Riflemen's website.)
UPDATE: Nearly five months after I wrote the above post, there was a mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida. A February 18, 2018, article in Politico.com by Bill Scher, "Why the NRA Always Wins," examines more closely the effectiveness of the NRA's political communications and organizing. Also following the Parkland tragedy, there has been some renewed focus on the role that pent-up anger plays in many shootings. See the February 14, 2018, article "Suspect in fatal Florida school attack is former student with 'anger' issues." See the 2015 article "Harvard Study Finds Anger Issues, Not Major Mental Illness, Tied To Gun Violence."