Why did people start to think Peter was the head of the church?
The question that is the subject of this post is one that should be of interest to those who have heard the many claims of papal primacy. Scripture nowhere indicates or suggests that Peter was the head of the church. How then, could people have begun to think so?
Papal Invention Hypothesis
There is always the possibility that the motivation was simply self-serving. The alleged successor of St. Peter created a story that Peter was the head of the apostles, and used political connections in Rome to force the story on the rest of the church within the Roman empire. That may be the most likely and reasonable explanation.
But there is a way that the legend could come to be, and this way is much more interesting.
False Cognate Hypothesis
The Aramaic name for Peter is transliterated Cephas in our English Bibles, and that name is usually pronounced with a soft "c". Nevertheless, a more accurate transliteration calls for a hard "c" or K. Thus, a better transliteration is Kephas.
In Greek, the word for head is κεφαλη which would be transliterated to Kephaleh. It is easy to imagine that someone with no knowledge of Armaic might mistakenly think that Kephas was etymologically related to Kephaleh. Thus, a group of Christians for whom Latin was their first, Greek their second, and Aramaic an unknown language, might easily misunderstand the appellation of Peter as "Kephas" to mean that he had been made the head of the apostles.
This kind of false cognate mistake is not without precedent. It is on the basis of a similar false cognate (this time within a single language) that Moses is sometimes depicted in ancient images with horns. This was the result of mistaking Kaeren (horn) and Karan (to shine).
Likewise the legend that the forbidden fruit was an apple arose (apparently) from a confusion between the Latin word malus (apple) and malum (evil).
Another option, of course, is that an enterprising pope or papal advocate took advantage of the false cognate to bolster an argument in favor of Petrine primacy.
Conclusion - Further Study
So far this is just a hypothesis that struck me as I was reading through Scrivener. What would be interesting would be to see if there is any record of the false cognate argument actually being used. Although I think it is unlikely that any such argument would have survived to present, if it was ever committed to paper.
I recognize that there are various arguments for Petrine Primacy, but those are really quite aside. If Peter is assumed to be the head of the church, there are various passages that can be pressed into service to try to support that hypothesis. There is, however, no reason within Scripture to suppose that Peter was the head of the church.
I also recognize that there are various extrascriptural sources that assert Petrine Primacy. The problem is this: most (and probably all) of those are folks who wrote significantly after the fact, and at a time when the bishop of Rome had begun to play imperial politics.