Francis I, the new pope, has only 1 lung. Note that.
Here is Aquinas on a newly relevant question:
Article 6. Whether lack of members should be an impediment?
Objection 1. It would seem that a man ought not to be debarred from receiving Orders on account of a lack of members. For one who is afflicted should not receive additional affliction. Therefore a man ought not to be deprived of the degree of Orders on account of his suffering a bodily defect.
Objection 2. Further, integrity of discretion is more necessary for the act of orders than integrity of body. But some can be ordained before the years of discretion. Therefore they can also be ordained though deficient in body.
On the contrary, The like were debarred from the ministry of the Old Law (Leviticus 21:18, seqq.). Much more therefore should they be debarred in the New Law.
We shall speak of bigamy in the treatise on Matrimony (66).
I answer that, As appears from what we have said above (3,4,5), a man is disqualified from receiving Orders, either on account of an impediment to the act, or on account of an impediment affecting his personal comeliness. Hence he who suffers from a lack of members is debarred from receiving Orders, if the defect be such as to cause a notable blemish, whereby a man's comeliness is bedimmed (for instance if his nose be cut off) or the exercise of his Order imperiled; otherwise he is not debarred. This integrity, however, is necessary for the lawfulness and not for the validity of the sacrament.
This suffices for the Replies to the Objections.I don't pretend to be a Canon Lawyer (IANACL). If you are a canon lawyer, or a suitable imitation thereof, please weigh in below. And let me make this obvious, in case any non-medievalists wander in: I'm not raising these questions as someone hostile to Catholicism. I'm not trying to dislodge the newly minted Francis. I'm just a humble medievalist.
Now, obviously, Aquinas and the Levitican law concern only what they decide are visible disabilities. I do wonder, however, if the late antique decree that barred the priesthood to self-castrators still applied to the medieval church, which I ask only because castration is not, in typical habits, thought to be visible (rather, as we see with Chaucer's uncertainly gendered Pardoner, castration troubles the operations of visibility and meaning-making).
In other words, visibility doesn't always work in any obvious way to classify impediments as significant. For still more on issues of visibility and disability, see Greg Carrier here. Also recall last year's précis of Maaike van der Lugt's "L'humanité des monstres et leur accès aux sacrements dans la pensée médiévale" [The humanity of monsters and their access to the sacraments in medieval thought], here, where I summarize her summary of some thirteenth-century quodlibetal material:
And then, finally, we have the problem of intersexed people. The church authorized their marriage, but only if they adopted either a feminine or masculine role, and stuck with it. Those without a preference were to remain chaste. Choosing which gender dominated was a knotty problem: some thinkers emphasized genitals, others secondary sexual characteristics (a beard, for example), and others comportment and behavior. Baptism wasn't a problem here, although in cases of doubt, the priest should give the child a masculine name, which could easily be made feminine if necessary (Robert would become Roberta, Gerald would become Daphne, etc.). Those intersexed people thought to have a dominant masculinity could even be ordained as priests.We therefore have a kind of muddled field of visibility and invisibility in the notion of the priest's being a proper, bodily representative of Christ on earth. With all due respect to Aquinas, all that's clear to me at the moment is that there's no single authority on whom we can rely.
Finally, for our readers with Google Books access, I direct you to Irina Metzler on the topic of medieval priests and disability, and for additional, relevant material, see Carol Rawcliffe, who summarizes British medieval legislation on disabled priests as part of her discussion on priests with leprosy. The key point from both works? Dispensations are possible, and, in practice, whatever these cultures marked as disability was nonetheless marked without its being a great impediment to the priesthood. Present under erasure, in a way.
In short--again, IANACL--because it is an "invisible" disability (though one now made visible perhaps to develop a supercrip narrative, as suggested here), and, furthermore, because Francis, like any priest, could simply obtain a proper dispensation, having only a single lung (or having, say, three lungs) presumably would not be sufficient to bar a man from the Papacy.
I'm inviting further discussion below, from people who actually know things about disability studies, canon law, and the complicated (and still very hot) issues surrounding the notion of the priest as representing Christ.