Catholics on campus are talking about sex.

Last night, a talk on contemporary Catholic sexual ethics kicked off the Lenten speaker series “What’s Sex Got to Do With It?”

A mixed crowd of undergraduates and graduate students listened to Boston College Professor of Theology Lisa S. Cahill call for religious dialogue to deal more directly with today’s sexual culture.

“How many of you know what ‘Humanae Vitae’ is?” Cahill asked, referring to Pope Paul VI’s 1968 letter affirming traditional Catholic teachings against birth control.

A few hands went up.

“How many of you know what hook-ups are?”

Many more raised hands and nervous laughter followed.

Cahill’s unexpected turn from papal encyclicals to sexual slang characterized an address that asked students to examine what religious tradition has to say about the sexual realities of college.

Cahill—who served as the former president of both the Catholic Theological Society of America and the Society of Christian Ethics—focused on the tension between Catholic sexual teaching and the modern culture of casual sexual interaction.

She urged a shift in discourse from “Humanae Vitae” issues, such as gay marriage, gender equality, and contraceptive use, to topics like casual sex.

During her talk, which was sponsored by Harvard’s Episcopalian Chaplaincy and Memorial Church, Cahill said many students she has spoken with feel uncomfortable with the culture of casual sex, despite its prevalence.

“The ideal is so far from the reality that the ideal can’t even speak to the reality,” Cahill said. “I’m not saying that Church doctrine needs to just capitulate, but those who are loyal to the tradition need to bring it forward in a more positive way.”

Cahill discussed the issue of personal integrity, referring to Pope John Paul II’s “Theology of the Body.” For John Paul II, the purpose of sex was two-fold—to express permanent love and commitment, and to procreate, she added.

Urging the audience to ask, “What does sex mean to us?” Cahill advocated a balanced consideration of doctrine and personal feelings.

Several students at the event responded with enthusiastic scrutiny, challenging Cahill with questions about Catholic attitudes toward abortion, evolution, and divorce.

Other students—representing a range of religions—had positive views about the sex talk.

“I think to have a talk like this on a campus that has been identified as not very religious is important because it provides a religious perspective on the hook-up culture,” said Christine M. Mitchell, a student at the Divinity School, referencing a Feb. 11 Newsweek article, “Harvard’s Crisis of Faith.”