Thomist philosopher Edward Feser has a curious way of defining free will and what it’s for, writing in a recent blog post the following: “[O]n the conception of free will as ‘freedom for excellence,’ which is endorsed by Aquinas, the will is inherently directed toward the good in the sense that pursuit of the good is its final cause.”
In other words, God hasn’t given you freedom to do what you want to do, but to do the most excellent thing–what God want you to do. You’ve been given free will by God to direct your actions toward God’s will, the pursuit of the good, which must be the “final cause” of all your actions.
But this is where Thomistic reasoning about sex clearly goes off the rails. The Thomist’s frowning on masturbation and oral sex (for example) becomes akin to the Leninist’s frowning on comrade Kandinsky for spending too much time painting and not enough time organizing for the Workers’ Party.
Put another way, Feser and Aquinas advance an ideological notion of what the human being is, harnessing the will to a singular focus that doesn’t take proper account of individual contingency, pleasure, whimsy, and private goals. It’s too cookie-cutter.
All serious business and no masturbation, sexual exploration, imagination, play, or art, makes Jack a dull and neurotic boy.
So if you’re going to forbid to humans something central to them (joy in sexual novelty), and reject gay marriage and gender equality (female priests), the reasons need to be very, very good ones. Simply saying, using pre-Darwinian reasoning, that God meant sex organs to be harnessed solely to reproduction and the ultimate good will not do when evolution has informed us repeatedly that the human being is not a unitary animal, but an evolved conglomeration of contingent and often open-ended purposes. A human being’s needs are multiple; her evolutionary strategy is re-purposing and variety; her focus is not most naturally on God as a universal singularity. Emily Dickinson nailed it with the following lines:
God is indeed a jealous God —
He cannot bear to see
That we had rather not with Him
But with each other play.
Compromise among the competing and layered parts of ourselves is thus more likely to make for human flourishing than blanket sexual repressions (no homosexuality, no crossing gender lines, no masturbation, no contraception, no sexual fantasizing, no porn, etc). Reasoning in the 21st century about human nature and sex while taking little account of evolution is barely reasoning at all.
“The fox knows many things, the hedgehog one big thing.” Evolution and Emily Dickinson are foxes, Feser and Aquinas hedgehogs.
Prometheus Unbound 