Impotence was a grounds for annulment but not infertility. First of all, the marriage act must be consumated to complete the marriage. Secondly, the possibility of procreation must be present, which would not be true if it was impossible even to complete the marriage act.
However, infertility, perhaps because of an older, less scientific viewpoint, was considered too subjective to be a grounds. How could someone know for sure that they were "infertile"? There were always the examples of Sarah and Elizabeth to remind people that "you never know."
Generally speaking, we are in agreement here. First come the vows of the couple, received by a priest in the name of the Church, and witnessed by at least two people. Then comes the marriage act, which consummates the marriage. Impotence would make this consummation impossible, in addition to ruling out the possibility of fulfillment of the spouse's marriage rights. By the way, the only exception to this general rule, would be a "Josephite" marriage (i.e., like Joseph and Mary), which is very rare, and must be pre-approved by the Church.
Secondly, the possibility of procreation must be present, which would not be true if it was impossible even to complete the marriage act.
If one or both of the couple was infertile, and yet they can marry based on the possibility of procreation, how is this different from a fertile couple using NFP? I say this, because the possibility of procreation is still present in their marriage. True, the intentions are different, but if the primary purpose of marriage is to beget children, and as long as the existence of this possibility is considered as the basis for marriage, it can be said that both infertile as well as NFP couples have that possibility.
Can it truly be said that the primary purpose of marriage is the procreation of children? Or can marriage be seen as a living model of the marriage between Christ and His Church, first and foremost? How can the Church permit Josephite marriages, however rare, if the primary purpose of marriage is the procreation of children? Or is there another aspect of marriage which is primary?
However, infertility, perhaps because of an older, less scientific viewpoint, was considered too subjective to be a grounds. How could someone know for sure that they were "infertile"?
Yes, but how about today? If a person is medically deemed to be infertile due to radiation treatments, for example, what then? What if a woman had to undergo a complete hysterectomy out of medical necessity? There would be a zero chance of her ever being pregnant.
There were always the examples of Sarah and Elizabeth to remind people that "you never know."
Of course I don't rule out miracles, but there are times when modern medical science can accurately assess an individual's infertility.
May a couple engage in the marriage act during those times of the month when a woman is infertile? How can this be morally right when the primary purpose of marriage, and therefore, of the marriage act itself, is to procreate children? To use traditional Biblical phrasing, wouldn't a man be "wasting his seed?" At those times, why would it not be unlawful?
Food for thought.