A big part of the reason why liberals spend so much of their time telling each other comforting lies about science proving their views is to paper over the reality that their ideology is fueled by little more than the basest emotionalism.

A recent headline from Mic.com editor Julianne Ross is a perfect example: “Stunning Photos of Deliriously Happy New Dads Is Perfect Response to Anti-Gay Activists.” The images show Toronto couple BJ Barone and Frankie Nelson overwhelmed with emotion as they hold baby Milo, who had just been born via a surrogate mother. Ross claims they’re “a simple yet powerful reminder that loving families come in all different forms,” which “proves — yet again — the universality of a father’s love for his child.”

“They are two compassionate people who felt all the emotions that every new parent feels,” says photographer Lindsay Foster. The, er, fathers are quoted as declaring: “Milo was born during World Pride. This picture represents everything Pride is about. Love has no color nor gender nor sexual preference. Love is unconditional.”

Now, I’m as touched as the next guy to see a bouncing baby boy used as a political prop just days after birth, but words like “response” and proves” lead one to expect something resembling argument—y’know, the archaic practice in which one person takes another person’s reasons for believing a certain proposition and explains why they’re incorrect, ideally with some sort of evidence.

Nothing of the kind occurs in Ross’s piece. It’s purely an emotional appeal, with the “stunning,” “adorable,” and “beautiful,” imagery meant to tug heartstrings rather than intellectually substantiate its case. The closest it comes to argument is the occasional gay pride slogan lifted from some bumper sticker.

“You should support same-sex marriage/parenting because aren’t these pics just precious?” isn’t even a serious point, let alone a “perfect” one. Some anti-gay types rail against homosexuality on the basis that picturing two men kissing or having sex is “gross.” If that’s an invalid argument against gay causes—and it is—then imagery pandering to the opposite reaction is similarly inadequate.

The only actual information we get about what kind of parents these two men will make is Foster’s statement that they “asked all appropriate questions of the birthing mom and the midwife, and educated themselves as best as they could for their son’s arrival.” That’s hardly a particularly high bar to clear—and certainly no response to the actual case against same-sex parenting.

The real dispute—which Ross can’t be bothered to even mention, let alone critique—has nothing to do with whether homosexuals can be as caring or attentive as heterosexuals, and everything to do with whether children need both a mother and a father. Can two dads make up for the absence of a mom? Can two moms compensate for missing a dad?

Conservatives say no. We think it’s absurd to look at the fact that it takes both sexes to create a child yet conclude those sexes are completely irrelevant to raising that child. And contrary to liberals’ imaginary monopoly on science, hard evidence agrees.

We know, for example, that men and women differ in the way we communicate, solve problems, react to stress, handle emotions, and more, which translates to distinct parenting strengths. Dr. Trayce Hansen explains that “relationships with both sexes early in life make it easier for a child to relate to both sexes later in life,” that “some stages [of development] require more from a mother, while others require more from a father,” and that “boys and girls need an opposite-sexed parent to help them moderate their own gender-linked inclinations.”

In 2012, Mark Regnerus of the University of Texas found that children of lesbians had statistically-significant disadvantages on 25 out of 40 outcomes such as being on welfare, sexually-transmitted diseases, and emotional instability, while children of gay fathers suffered in 11 out of 40 (Regnerus was widely demonized for these findings, but the University of Texas dismissed charges of academic misconduct).

In another study, published in Review of Economics of the Household in fall 2013, Douglas Allen examined a large sample of children in Canada (where marriage-equivalent same-sex benefits have been established long enough for better comparisons to traditional families) and found that those raised in same-sex households were only 65% as likely to graduate high school as kids with a married mother and father—despite gay parents themselves being more highly educated than straight ones.

But the science is settled! liberals wail. Sorry, wrong again—regarding the American Psychological Association’s 2005 assurance that there’s no difference between standard parents and same-sex ones, Louisiana State University family studies scholar Loren Marks writes:

“[N]ot one of the 59 studies referenced … compares a large, random, representative sample of lesbian or gay parents and their children with a large, random, representative sample of married parents and their children. The available data, which are drawn primarily from small convenience samples, are insufficient to support a strong generalizable claim either way.”

This and other methodological errors, such as selection bias, taking parents’ self-reported word at face value, and grouping gay parents under the same-sex column even when the child actually does have an opposite-sex parent (such as from a prior marriage) in the picture, are common in the gay lobby’s studies—including the latest one from the University of Melbourne.

These would be big problems if liberals sincerely cared about the evidence for or against their views. But all they really want out of studies is sound-bite fuel to close the gaps emotional manipulation can’t quite make, and a convenient headline or cherry-picked statistic doesn’t have to be true to do that job. To the Left, there is no scientific method—just whatever method gives them the outcome that feels nicest.