Most people surely agree with President Donald J. Trump’s calling the massacre in Las Vegas on Sunday, Oct. 1, an “act of pure evil.” No one would dispute that Stephen Paddock is primarily responsible for this evil. However, can we also say that gun manufacturers bear some responsibility for the evil of Las Vegas, Orlando, San Bernardino, Sandy Hook and the carnage on our streets every day? What about politicians who refuse to enact reasonable gun control laws? In the language of Catholic moral theology, do they cooperate in this evil?

A recent column in The Economist maintained that some believers see evil as an inevitable element of the human condition. Thus, regulations such as gun control designed to eliminate evil are futile. But this simplistic understanding of evil leads to fatalism and reduces responsibility for violent tragedies to the perpetrator alone and/or some malevolent cosmic force (e.g., Satan).

The understanding of evil in the Catholic moral tradition can help us think through such issues more fully. Catholic teaching assigns guilt first of all to perpetrators of sinful acts themselves, but it also underscores the social conditions that contribute to sin.

Those who do not do what is reasonably possible to keep guns out of the hands of criminals contribute to what Cardinal Timothy Dolan labeled a “Culture of Death.”

In his encyclical “Sollicitudo Rei Socialis,” St. John Paul II spoke of “structures of sin” that individual sins create and sustain. Because we are all ensnared to one degree or another in these webs of sinful relationships, practices, institutions and laws, it is impossible to avoid some degree of complicity in them. And as Catholic ethicist Julie Hanlon Rubio argues, “if social evil is occurring, we can be held accountable for contributing to it.” We need to take steps “to lessen our cooperation with sinful structures.”

Those who do not do what is reasonably possible to keep guns out of the hands of criminals contribute to what Cardinal Timothy Dolan labeled a “Culture of Death, where human life and dignity are cheapened by the threat of violence.” They cooperate in the evil of gun violence.

In Catholic moral theology, there are different forms and degrees of cooperation in evil. Formal cooperation in evil is never permissible. It entails either directly participating in the act itself or “sharing in the immoral intention of the person committing it” (“Evangelium Vitae,” No. 74). Being an accomplice in a shooting would constitute formal cooperation in evil. Providing the shooter with a gun with the intention of abetting a murder is also formal cooperation in evil, even if the accomplice does not physically participate in the act.

Gun manufacturers may not be guilty of formal cooperation in evil. But this does not exonerate them from material cooperation in evil.

Catholic ethicists have long regarded the principle of cooperation to be exceedingly difficult to apply in many cases. For starters, we cannot always know the intentions of others. In this case, let us assume that most gun manufacturers do not intend for their products to be used as murder weapons. Furthermore, The Catechism of the Catholic Church (Nos. 2263-65) allows for the lethal use of force in self-defense if it is a necessary last resort and proportionate to the situation. Authorities entrusted with preserving safety and peace (i.e., police and military) may use arms against an unjust aggressor if, and only if, these conditions are met. In other words, guns can serve a legitimate, albeit limited purpose.

Therefore, gun manufacturers may not be guilty of formal cooperation in evil. But this does not exonerate them from material cooperation in evil, as theologians James F. Keenan and Thomas R. Kopfensteiner explain. If gun manufacturers do not attempt to “distance themselves” as much as possible from the killing of innocents by criminals, they are guilty of illicit material cooperation in evil. Furthermore, there must be “a proportionately grave reason” to produce the guns that have killed more than 1.5 million people in the United States since 1968 (66 percent of these deaths were suicides, and 33 percent were homicides, according to Politifact).

Rather than distancing themselves from the evil of widespread, tragic gun violence, the gun industry helps create the conditions for its possibility.

It is hard to imagine such a reason. Our country now averages more than one mass shooting per day (defined as four or more victims). Americans own 42 percent of the 644 million civilian-owned guns in the world. And the evidence is clear: More guns lead to more lethal violence, fewer guns correlate with less lethal violence. For this reason, the United States Conference of Catholic Bishops has called for the “eventual elimination” of handguns in the United States, with exceptions such as police and military firearms. We might add necessary, but not all forms of, hunting to this list.

Rather than distancing themselves from the evil of widespread, tragic gun violence, the gun industry helps create the conditions for its possibility. According to the Brady Center, gun manufacturers know that their products become murder weapons far too often, and 5 percent of gun dealers sell 90 percent of these firearms.

In addition to mass production, gun manufacturers have acted otherwise to ensure the increasing proliferation of guns. As this report in The New Yorker describes, the industry “markets fear,” making people believe they need guns to be safe even though violent crime has declined by 50 percent since 1991 and owning a gun greatly increases the risk of homicide or suicide in a home. The gun industry also donates millions to the National Rifle Association in order to influence lawmakers who might otherwise curb the industry’s $12 billion yearly profits through gun regulations. The industry’s lobbying efforts also won civil immunity from Congress in 2005, which shields them from civil liability for deaths and injuries resulting from their products.

It is perhaps no wonder that Pope Francis has called Christian gun manufacturers—and Christians who invest in gun manufacturing—hypocrites.

In short, producing and selling assault weapons in the United States that are not designated for law enforcement or the military—and wind up giving gangs and people like Stephen Paddock massive arsenals—is illicit cooperation in the evil of gun deaths. It is also an immoral act per se. There is no justifiable reason for it that squares with Catholic teaching on the morality of acts (see The Catechism, Nos. 1749-56). At a minimum, gun manufacturers should mitigate the negative consequences of producing firearms by supporting sensible gun control laws, such as those endorsed by the U.S.C.C.B.

Politicians who enable the proliferation of assault weapons are also guilty of illicit cooperation in evil. Those who voted against background checks, closing gun purchase loopholes and the assault weapons ban have these votes on their consciences. Even though support for keeping gun ownership legal remains strong, the majority of Americans support these measures. Investors should use strategies such as shareholder advocacy or divestment to push gun manufacturers to do the right thing. Investing is always a “moral choice” and cannot be driven by profit alone (“Centesimus Annus,” No. 36).

Everyone must do their part to promote the culture of life by fighting the social sin of gun violence.