It’s no surprise then, that the push for porn filters comes from a religious segment of campus. The Notre Dame letter, for example, was part of a yearly anti-porn campaign by a campus group called the Students for Child Oriented Policy (SCOP). The group advertises itself as nonpartisan and nonsectarian, but has hosted several anti-abortion talks on campus and once circulated a petition asking Notre Dame to take a “clear stand” against same-sex marriage. Irvine, meanwhile, is president of a pro-heterosexual-marriage campus group that has been accused of promoting intolerance against LGBTQ students.

Martinson said the religious aspect was important to him personally, but that he preferred to focus on the issues of addiction and objectification of women. “It’s really important to frame things from a secular perspective because you just appeal to more people,” he said.

One Harvard student who reached out to Martinson about the filter is a converted Catholic and co-president of the Anscombe Society, which advocates for “premarital abstinence and sexual integrity.” (The group is also strongly opposed to same-sex marriage.) Will Long—a computer science and government major who recently penned an op-ed for The Harvard Crimson on “recovering the beauty of sex”—linked the use of pornography to campus hookup culture and dating apps, which he said corrode relationships between students.