Read the introduction to this series, first.
2) Negative side effects. Attending homosexual practice is a disproportionately high rate of negative side effects as regards (a) health (sexually transmitted disease, mental health problems, and shortened life expectancy) and (b) relational dynamics (short term relationships, high numbers of sex partners). These problems are, in the first instance, attributable to the non-complementarity of homoerotic unions: the extremes of one’s sex are not moderated and gaps are not filled. Approving homosexual behavior will also contribute to the gender identity confusion of adolescents and, by virtue of denying any significance or value to male-female differences, will bring about the destruction of all gender norms and societal endorsement of transvestism and transgenderism. See The Bible and Homosexual Practice, 452-60, 471-85; more recently, my online “Immoralism, Homosexual Unhealth, and Scripture: Part II: Science” (here for pdf, here for html).
Whereas Gagnon was unwilling to admit biological evidence in his discussion of ‘nature’ he is quite ready to debate the scientific evidence when it comes to the health effects of homosexual behavior. Again, in limiting the scope of this debate, I will not attempt to discredit the particular studies he cites in the articles underlying this argument. Nor would it serve any purpose for me to simply bring up different studies with different results and make this an argument about whose evidence is more credible. Instead I will focus on the structure of his argument and demonstrate its flaws by highlighting parallel arguments.
Gagnon says that “attending homosexual practice is a disproportionately high rate of negative side effects,” and that “these problems are, in the first instance, attributable to the non-complementarity of homoerotic unions.” The first statement is scientific, the second is very much not. There is nowhere near the degree of evidence a scientist would require to make an assertion like that second statement, not least because complementarity is not a scientific category. Again, Gagnon has imported his Biblical thinking into his secular argumentation and though he goes to great lengths in his other articles to use scientific studies which support his belief in complementarity the studies were not conducted with the philosophical category of complementarity in mind, nor would their designers endorse the conclusions Gagnon draws from them. The most incautious of scientists would only ever attribute an observed phenomenon to a specific cause after multiple, multiple studies and then only as one cause of several under specific circumstances. Gagnon’s error here is in leaping from observed phenomena to a presumed cause, especially when the cause is one that we know was already in his mind prior to reading the studies.
The fact is that there is a disproportionately high rate of negative side effects to being African American, or Hispanic, or poor, or a woman, or living in the 2/3 world. It is just irresponsible to ignore the obvious social causes of negative side effects and leap instead to biological ones. One might just as reasonably conclude that white people have a biological tendency to oppress other people. Furthermore, even IF it could be conclusively proven that a genetic homosexual orientation was linked to shorter lifespans and mental health issues that would still not be moral grounds to oppose cultural acceptance of homosexuality. It’s repugnant even to suggest it. Would you argue against cultural acceptance of people with Aspergers? Down’s Syndrome? Blue eyes?
Gagnon might respond that these examples are not sufficiently analogous. He might argue that homosexual orientation, even if biological, is only a predisposition that we can still separate the behavior from the orientation. Very well, what about people with an imbalanced metabolism? Being fat is unambiguously unhealthy. These people have an unfortunate genetic condition, which is exacerbated by behavior, leads to insecurity, the break-down of relationships, and shortened life expectancy. What about people with a genetic predisposition for depression?
The point is, even in cases where the results of genetic predisposition for certain behaviors are unambiguously negative (which is not the case with homosexuality), we would reject any suggestion that members of society be discriminated against on that basis. This argument is dubious on scientific grounds, and bankrupt on moral grounds.