Perpetual virginity of Mary: why did Mary see "not knowing man" as an obstacle to the conception of Jesus?

Many of the answers here in this parallel question appeal (as OP seems to do) to the idea that Mary's question to Gabriel, "How can this be, since I know not a man?' only makes sense if she was already committed to remaining perpetually virgin. After all, the argument goes, she knew she was engaged, she knew consummation was coming, and she must have known babies come from consummation so the question makes no sense unless she also knew she had vowed never to 'know' a man.

Here is the link from which I am summarizing below.

But there is a time element that is not directly addressed in Luke's discourse which renders the above argument moot. A first century Jewish marriage happened in 3 distinct stages.

1) There is a betrothal (ketubbah) which is predominantly a legal contract (often between parents of the espoused). The betrothed couple has not yet consummated the marriage (the marriage bed) but the marriage is fully engaged at this point; thus, Joseph's thought to divorce Mary quietly makes sense because, although not yet consummated, the marriage was already valid in the betrothal.

2) Consummation (chuppah) occurs when the groom is able to fulfill the financial aspect of the betrothal contract with the father of the bride. He comes to the bride's house at the prearranged time where the bride is waiting with her maidens for the groom and his entourage. Consummation (sexual union) takes place in the bride's home while the wedding party waits (eww!). It may take up to 7 years between betrothal and consummation, depending upon the contractual obligations of the betrothal and the financial means of the groom.

3) The wedding feast (ala John 2) follows the consummation and the trek to the home of the groom.

Given the complete lack of information in Scripture regarding the specifics of the betrothal agreement including but not limited to; a) the exact date the betrothal contract was initiated, b) the agreed upon financial requirements placed upon the groom, and c) the expected time lapse between contract and consummation, it is not so hard to understand Mary's question.

Gabriel's pronouncement appears to lack a delay in the action foretold. He does not say, for instance, "At this time next year.", as was told to Abraham in Gen. 18. I do not know if the Greek grammar of Luke 1:31 indicates timing of the future fulfillment of this prophesy but it reads as more immediate than not. "The Lord IS with you.", and, "You HAVE found favor with God.", seem to indicate that some prerequisites have already been met.

Mary may well have understood the immediacy of the prophesy (as we who see it from this end of history know that it was) and known that their contracted consummation date was years in the future, as was common in her time and culture. Therefore her question to Gabriel, "How can this be?", might be paraphrased as, "How can I conceive soon, as you say, since I am currently a virgin and there are still 3 years until my marriage to Joseph is consummated?"

This understanding does nothing to diminish the character of Mary who had already found favor with the Lord and who, upon hearing a promise of the 'impossible', leaned into the promise with humility and faith; the faith of Abraham you might say. It is, however, a culturally plausible and scripturally sound alternative to the notion that the only logical ground for Mary's question is to assume a vow of perpetual virginity.

Perpetual virginity of Mary: why did Mary see “not knowing man” as an obstacle to the conception of Jesus?

Mary, like Joseph, understood natural law. Specifically, one cannot have a baby if they are a virgin. It requires a partner of the opposite sex. (Joseph was going to send Mary away in Matt. 1:19 because he understood natural law.)

For those who deny that Mary ever intended to remain a virgin her whole life, how is this refuted?

The wording of the question is a little confusing to me. I think it's nearly impossible to know what Mary's intentions would be as there's no clear text. The passage below indicates Jesus' had brothers and sisters and the most logical understanding of the text would be that Mary or Joseph produced the brothers and sisters, especially given how honorable they were in previous passages.

53 When Jesus had finished these parables, He departed from there. 54 He came to His hometown and began teaching them in their synagogue, so that they were astonished, and said, “Where did this man get this wisdom and these miraculous powers? 55 Is not this the carpenter’s son? Is not His mother called Mary, and His brothers, James and Joseph and Simon and Judas? 56 And His sisters, are they not all with us? Where then did this man get all these things?” 57 And they took offense at Him.

When one way of interpreting a passage is absurd, that shows we aren't to interpret it that way. Obviously she didn't think the angel was just telling her she'd conceive a baby with Joseph or else she wouldn't have said what she said. So she clearly understood the angel was telling her she would soon have a baby without having slept with Joseph, and hence her question, because she didn't understand how that could be. Although what the angel said sounds a little ambiguous to us, her response clearly shows the connotations of what he meant: the conception will not come from sex with Joseph. Mary's response shows us how she understood what the angel meant, and as the angel doesn't correct her, we can know this is the correct understanding.

ειπεν δε μαριαμ προς τον αγγελον πως εσται τουτο -επει- ανδρα ου γινωσκω

Luke 1:34 - TR (Stephens 1550, Beza 1598, Elzevir 1624 and Scrivener 1894 are all identical.)

Then said Mary unto the angel, How shall this be, seeing I know not a man? KJV

The Greek conjunction ἐπεί epei (see Strong 1893) cannot be manipulated into meaning something with regard to a time sequence in the future. The force of the word is 'because' or ' for the reason that'. Note that the KJV quite correctly renders the conjunction as a present participle.

"How shall I bear a child in my situation of not (presently) knowing a man ?" . . . is all that can possibly be construed from the Greek wording .

[ There is a disputed translation of Luke 7:1 (see interlinear) where epei is rendered 'and when' but the meaning has the force of 'and for the reason that he had completed ...'. It is not a future consequence but, here in Luke 7:1, epei conveys a decision made upon a completed situation. ]

As to Mary's words in Luke 1:34, The Douay-Rheims also correctly renders the conjunction (from the Latin Vulgate) using the very apposite English conjunction 'because':

And Mary said to the angel: How shall this be done, because I know not man?

However the D-R then mis-translates ανδρα (from aner - an identifiable man) and renders it as though it was ἄνθρωπος (anthropos - humanity). This may be a fault of the Latin-from-Greek translation of the Vulgate or it may be a fault of the English-from-Latin translation thereafter.

'Know not man' is quite inappropriate, here. It should be 'know not a man', meaning a particular man. Only an impossibly travelled harlot would know anthropos. Broadening the meaning of 'a man' to 'mankind' in no way strengthens an argument for perpetual virginity.

This attempt to extend Mary's utterance in perpetuity has resulted in very inappropriate English words being put into her holy lips with regard to humanity.

Mary was already espoused to Joseph before Gabriel appeared to her (see Luke 1:27 - ... to a virgin espoused to a man ... ). Hardly the action of a woman who intends, in perpetuity, to remain a virgin. But, having not (yet) come together (Matthew 1:18), she did not (at that stage) know a man.

What is much more relevant regarding the certainty of the situation is Matthew's wording in Matthew 1:24, 25 :

Then Joseph being raised from sleep did as the angel of the Lord had bidden him, and took unto him his wife: And knew her not till she had brought forth her firstborn son: and he called his name JESUS. [KJV]

Had Matthew wished to convey - without a trace of ambiguity - that Mary had remained a virgin thereafter, Matthew would have stopped writing after 'knew her not'.

... and took unto him his wife and knew her not [Full Stop]

Thereafter he would have made a new sentence regarding the name of Jesus. But he does not do that, he continues :

... until she had brought forth the son of her (in literal) ...