Take the most fundamental argument found there — the “Argument from Crucial Distinction,” which is meant to show that the concept of “marriage” can’t apply to same-sex couples. Claiming to ground their argument “in our moral intuitions about what the critical features and norms of marriage are,” the authors make a series of assertions: first, a marriage must be “meaningfully different” from other kinds of relationships (like friendships, tennis partners, business partners, and so forth); second, the crucial difference lies in the relationship’s orientation to raising children and its devotion to norms of “exclusivity, permanence, and monogamy.” The authors call this the “conjugal” view of marriage and claim it can only apply to “a comprehensive union between a man and a woman (with the unifying good of the relationship being procreation)…”
The authors are well aware that another view of marriage — which they dub the “revisionist” view — prevails among many people today. According to the revisionist view, marriage is a relationship based on romantic love and oriented toward the emotional and sexual fulfillment of both partners. Children may be a part of this union, but they need not be. Same-sex marriage has come to be widely accepted because this revisionist view has widely supplanted the conjugal view in our culture.
I urge readers to spend time at the website for themselves, reading and watching the slick YouTube videos (here’s one) that purport to show that what “we” really mean by a marriage is the conjugal view that excludes same-sex couples. I predict that not a single person will persuaded by the question-begging, circular argument.