Eusebius identified the two Johns and so had to choose one tradition over the other. It is mentioned by Philip, another church historian. That Eusebius was innovating is seen in his following the suggestion of Dionysius that a different John wrote Revelation, contrary to the earlier writers. He is also strangely silent about Clement's claim that the ministry of the twelve ended at the time of Nero. So we know that he passed over material that didn't fit his reconstruction. Another example: he doesn't mention Gaius' rejection of John's Gospel, even though he discusses his rejection of Revelation.
Again though, I think it's problematic to appeal to the dearth of evidence when the apostle's martyrdom is actually far better attested than John's natural death. Is there in fact a single reference to John's natural death in the fathers before Eusebius?
If you can point to anywhere where John the Apostle should have been mentioned had he been martyred, I'd be interested. Most of the early writers were more interested in the Evangelist, and once the two became widely identified, the martyrdom tradition would have been superseded anyway.
How would you define the marks of an early cult of his death? Do we have this kind of evidence for Peter or Paul? What would you look for beyond it's commemoration in the martyrologies, which we do have?
We have two later writers citing Papias, though obviously under the mistaken belief that there was only one John. What's the alternative scenario? That they made it up? It seems problematic to me to simply dismiss them because they have added an interpretative layer. How else would you account for their statements? If the two Johns became widely identified, it would make sense that they spoke of the Evangelist as the John that was martyred. It doesn't make sense that they would have made up a quote from Papias, when it serves them no interest and when one of them tries harmonizing it with the alternative tradition by placing the martyrdom in Trajan's reign.
As is Eusebius.
Are you sure it can be described as "weak"? Clement provides a list of non-martyrs and begins with Matthew. I'm not saying it proves it beyond doubt, but it is very suggestive at the very least:
"Matthew, Philip, Thomas, Levi and many others” escaped public confession of Christ (
Strom. 4.9)
Why isn't John's name there? John the Apostle was one of the foremost of the twelve apostles. Had he just been a minor figure, I could understand his not being mentioned specifically, and just being included under the 'others'. The list instead begins with Matthew, whereas John, as the more prominent figure, would have been the natural choice to commence the list with. Peter and James we know were martyred.
Clement also places the deaths of the twelve apostles before the end of Nero's reign, and a number of scholars have accused him of contradicting himself by placing the Evangelist's life later, but this only contradicts the assumption that the apostle and evangelist were one and the same.
They don't always spell it out, and this applies to Peter and Paul as well, but sometimes they do. The Syriac Martyrology of Edessa does, and associates it with Jerusalem, as do a few others.
Not sure what's dubious about it. It's certainly fragmentary, though there's far more evidence than for the natural death of the Evangelist.
This work is often attributed to Cyprian, but since there's no name attached, Charles simply refers to it as a North African work. The ANFs collection thinks it was written by an African bishop about the time of Cyprian and that it probably was Cyprian. Here's the reference:
ANF05. Fathers of the Third Century: Hippolytus, Cyprian, Caius, Novatian, Appendix - Christian Classics Ethereal Library
Not if you place the evidence side by side. I know of only one text affirming the Evangelist's natural death in the period before Eusebius. Could you say the evidence for the Evangelist's natural death is stronger than that of the Apostle's martyrdom, which is attested by two Gospels, Papias, Clement (indirectly, but on two different occasions), Cyprian (or other writer) and others?
From my perspective, I would ask, which theory satisfies the most amount of evidence. The view that there were two Johns and that the Elder was the Evangelist takes care of all the evidence without any need to explain it away, to place unnatural interpretations on Jesus' prophecy, to dismiss Papias and the martyrologies, to make Clement contradict himself, etc. It only requires that these two Johns were later confused, and this kind of confusion was common and hardly exceptional.