I’ve had a modest insight: the dividing line that I’ve been trying to articulate between Thomists and myself surrounding gay marriage can actually be pretty succinctly stated: Thomists take clues from the nature of form to guide them in how an issue ought to be navigated, and I’m arguing that we should take clues from the nature of change.
Whether it’s woman’s “end” or the penis’s, both appeal to aspects of nature that we actually observe, but one leads to an argument for heterosexual conformity (follow the given, or an ideal derived from the given, or a Golden Mean), while the other appeals to allowances for nature’s dicing of diversity (variant expression along a continuum).
The Thomist position is grounded in hubris (one can know the right thing to do; one size fits all); mine is grounded in epistemic humility (we don’t really know how the contingent inner logic of a variant might actually benefit the organism in its contingent environment, and thus how the future might play out if we take a hands-off or “let it be” approach to its expression).
Both of us are reasoning from how we take nature to be most essentially (form v. evolutionary change), and are deriving, from our particular emphasis, an ought (generally follow the Golden Mean vs. generally allow for the Invisible Hand of evolution).
In practice, of course, both form and change come under consideration whenever we try to navigate a situation. Just like we, in a mixed economy, leave capitalism to itself unless it’s obviously running over a cliff (such as with the banking crisis), so we do the same with evolutionary diversity (pedophilia as a sexual variation along the human continuum of sexual preference is a “Big No,” gay marriage is a “Tolerable Yes” that we can be presumptively neutral about; let the experiment take place, as with marijuana legalization, and see how it plays out).
Or at least I think gay marriage should be a yes.