Naturally, sources are virtually never given for this claim. The actual decrees of the council are available at the link in Latin, and while my Latin is rudimentary, as far as I can tell there is no mention of any issue of women's souls or humanity at all.
So what is the truth? Well, it's made up; there wasn't debate about whether women were human or whether women had souls to begin with, much less vigorous debate decided by a single vote. This article (also available here) called "The Myth of Soulless Women" from the magazine First Things goes into some depth about it. See also here, a similar article by the same author. The short version is that the whole thing comes down to a misunderstanding of an account of a council (which may not have even been the Council of Macon). This account comes from Gregory of Tour's work "A History of the Franks" and is found in Book 8 Chapter 20. From the 1927 translation by O.M. Dalton (volume 2, page 345), we see:
"At this council there was a certain bishop who defended the opinion that women could not be included under the general description ‘man’; but he accepted the reasoning of his brethren, and said no more. Their arguments were as follows: The holy book of the Old Testament teaches that in the beginning, when God created man, He created them male and female, and called their name Adam, which, being interpreted, means earthly man; even so He called the woman Eve; of both He used the word ‘man’. And the Lord Jesus Christ is therefore called Son of man, because He was the Virgin’s son, which is to say, the son of a woman. To her He said, when He was about to change the water into wine: ‘ Woman, what have I to do with thee?’ and that which follows. They brought other convincing testimony, and there this matter rested."
And that's it! A simple question about the meaning of a word; this was much more a matter of grammar than theology. One has to stretch a lot to make it into a question of whether women were human or had souls. Even worse for those who try to claim it was settled by one vote (or was even a contested question), what is actually described is one bishop brought up the subject, the other bishops explained how he was wrong, and he accepted it and did not press his case. All of this is well explained in the linked article, which has been online since at least the year 2000 so it is not like the information could not be found, meaning people who propagate this false claim are with even less excuse.
Why does this blog post exist, then, if all the information is already in an online article presently available? Well, there are a few points not mentioned in it I wanted to note. While the above article goes into the original source of this error about a council arguing whether women have souls, it doesn't talk about where the even more inaccurate claim that it was decided by one vote came from. The farthest I have traced that back is a 1973 book called "The Rape of the APE" (APE stands for "American Puritan Ethic") by Allen Sherman, best known for his comedic song "Hello Muddah, Hello Fadduh". While this might not be the original source of the "decided by one vote" claim, it seems to be the one that popularized it. This book makes the following claim on page 181, italics original:
"In the year 584, in Lyons, France, 43 Catholic bishops and 20 men representing other bishops held the Council of Macon, which included the most peculiar debate since the world began, a discussion which, for nonsensical content; surely exceeded the Mad Hatter's tea party. The subject of the debate was a serious world problem of the time: Are women human? After many lengthy arguments, a vote was taken. The results were: 32 yes, 31 no. Women were declared human by one vote."
Yes, that semicolon did come after the word content despite the fact it should be a comma. Absolutely no source is made for this. Indeed, this chapter of the book, which is about various alleged mistreatment of women in the past, is filled with other inaccurate or exaggerated claims, almost all given without any citation whatsoever. Perhaps people should not uncritically take information about history from a man whose main claim to fame was making goofy novelty songs.
It's not as if people didn't know, even back then, that the claim was false. It was pointed out how the Council of Macon never debated the humanity of souls or women back in a 1916 issue of The Atlantic (January 1916, in the letters section).
But perhaps someone would object to the above counterarguments on the part of bias. After all, First Things is Christian magazine. And perhaps the person who wrote the letter to The Atlantic had their own biases also. But the requirement of evidence should be on the side of the person making the claim that there was any serious debate on whether women were human, meaning even if the sources I cited were the most biased people ever, it still wouldn't solve the issue of the lack of any primary source ever offered for the Council of Macron debating whether women are human or have souls.
However, to let the matter be decided hopefully beyond all doubt, let's check a source that cannot be accused of bias of wanting to make Christianity or Catholicism look good in regards to its treatment of women. Specifically, I refer to "Eunuchs for the Kingdom of Heaven" by Uta Ranke-Heinemann. Now, this book has a lot of problems, making some claims that don't seem backed up by its citations or claims made without a citation I can't find verification for. For example, take this claim from it (page 187) which I have seen repeated online. Referring to Thomas Aquinas, it claims:
"And he knows what this inconvenient situation can lead to: "Because there is a higher water content in women, they are more easily seduced by sexual pleasure" (Summa Theologiae III q. 42 a. 4 ad 5). Women find it all the harder to resist sexual pleasure since they have "less strength of mind" than men (II/II q. 49 a. 4)."
Summa Theologiae III q. 42 a. 4 ad 5 has not the slightest thing to do with women, water content, or sexual pleasure (its topic is about whether it was correct or not for Jesus to leave the writing of the Bible to others). And Summa Theologiae II/II q. 49 a. 4 also says nothing about women either and is discussing the aspects of prudence.
Also, I feel that this review
from the New Oxford Review also brings up some valid points, even if it
must be accepted that it is from an explicitly Catholic source which is
therefore biased. Now, someone can find positive reviews in popular magazines, but actual historians and scholars tend to be less positive. For example, the review of it from the journal
"History" concludes:
"[I]f it were presented simply as a personal document it would doubtless
command respect. But as supposedly historical argument it is
lamentable; the anachronistic assumptions and value-judgements which
fill every page would barely gain a pass-mark for a first-year
undergraduate essay."
("History" Volume 78, Number 252 (February 1993), pages 65-66)
Okay, so why am I spending a bunch of time criticizing the source I'm citing as evidence? It's because of those problems that it serves as an especially strong source here. "Eunuchs for the Kingdom of Heaven" is a rather polemical work about poor treatment of women by the church and it is willing to seize onto various questionable claims to argue its thesis. So, what does this work, which has every reason to use the Council of Macon as an example of how poorly esteemed women were by the church, have to say? Here's what it says on page 190-191:
"We may note in passing that as bad as this degrading of women by the
Church was, it must be made clear that the worst accusation–that the
Church doubted women had a soul or were human at all–is untrue. One
often hears and reads that at the second Synod of Mâcon (585) the
participants disputed whether women had souls, but that never happened.
Souls were not the issue. Gregory of Tours, who was there, reports that a
bishop raised the question, "whether woman could be called 'homo." Thus
it was a philological question (though raised because of the higher
value that men placed on themselves): homo in Latin means "person" as
well as "man," as do cognate words in all the Romance languages, and as
"man" does in English. The other bishops, Gregory reports, referred the
questioner to the story of Creation, which says that God created man
(homo), "male and female he created them," and to Jesus' title "Son of
Man" (filius hominis), although he was the son of a virgin, and hence
the son of a woman. These clarifications settled the issue: the term
homo was to be applied to women as well as to men (Gregory of Tours,
Historia Francorum 8, 20)."
This work--which, again, is all about how badly the church treated women, and is willing to engage in questionable arguments to prove that point--still says this claim is totally wrong. That really should clinch it. Maybe you don't trust Fox News because of its conservative bias, or MSNBC because of its liberal bias, but it's exactly because of that bias that if Fox News is defending a liberal from an attack, or MSNBC is defending a conservative from an attack, that's a pretty good sign that the attack in question is without merit. And that's the case here. If even "Eunuchs for the Kingdom of Heaven" is willing to say this claim is false, that should close the case shut.
Thus, this whole claim about the Council of Macon debating whether women had souls is false, and even more absurd is any claim it was decided by a single vote. Yet people, most distressingly, have propagated this false claim despite there not being evidence for it and without providing any evidence for it themselves. And thus in this way are false claims spread, due to people not bothering to make any attempt at verifying the claims they make.