It's clear we have a problem with gun violence: the numbers of people who die from guns, whether shot by others or as suicides, are far higher in the US than in comparable developed nations.
We can argue about the causes: is it violent movies, television shows, video games? Is it laws that allow people to buy guns without licensing or background checks?
The gun makers, it turns out, are willing to spend money on the bet that playing violent games will encourage people to buy guns: they work with the developers of the games to make sure their guns get prominent placement. Meanwhile, they donate lots of money to the National Rifle Association, whose leaders say the problem is violent video games, not gun ownership. And other people say the problem is neither guns nor violent cultural artifacts, but untreated mental illness.
In short, we have an epidemic problem. The more time we spend arguing about it, the longer it will take to arrive at a solution.
If the epidemic involved disease, and there were multiple possible transmission vectors, we'd be addressing them all, rather than arguing about which was the most important factor.
In this case, we have multiple factors that may be contributing to the problem. Rather than arguing about which is most important, we need to address them all.
We need legislation that requires background checks and licensing, nationwide. We need research and education about the effects of watching violent video and playing violent games. And we need better recognition and treatment of mental illness, and a reduction in stigmatization of mental illnesses that leads people to refuse treatment.