Why Was the Gospel of John Attributed to John?

Some of the same objections to Matthew having written the First Gospel apply to John the son of Zebedee having written the Fourth. Unlike Matthew, John did not copy any of our other Gospel sources, and so that’s not the problem that it is for Matthew (who surely, if he was an eyewitness, would not have taken his stories about Jesus from what he found in someone else’s written text). But there is an even higher probability, bordering on certainty, that John the son of Zebedee could not write....