Irenaeus And The Evidence For Gospel Authorship

I've been having a discussion with a skeptic who has repeated a common argument against the traditional authorship attributions of the four gospels (and, by implication, Acts). It seems that, for many skeptics, Irenaeus is the earliest extant source they're aware of who names an author of one or more of the gospels. They may be aware that Papias names Mark as the author of the second gospel, but think that Irenaeus is the first to give us evidence for John's authorship of the fourth gospel, for example. They suggest, then, that the attribution originated with Irenaeus or some other source around his time, and they suggest that Irenaeus or some other source responsible for the attribution was just speculating or didn't have much information to go by.

In 2007, I wrote a four-part series discussing some of the lesser-known evidence for the traditional gospel authorship attributions. I discuss some of the evidence for the widespread acceptance of those attributions around the time of Irenaeus, thus suggesting that the attributions originated earlier. And I discuss some of the evidence within Irenaeus that suggests his reliance on earlier sources. I also discuss some of the evidence for gospel authorship in pre-Irenaeus and non-Christian sources. You can read the series here, here, here, and here.