I recently finished reading Steve Hays' reply to Philip Blosser on the subject of sola scriptura. Steve makes many good points, and I highly recommend reading it. In the coming days, I want to add some comments to Steve's, primarily concerning the church fathers. Blosser made a lot of false or misleading claims about the fathers, often without providing many details to interact with. I want to emphasize or expand upon some of the points Steve made.
Near the end of his response to Blosser, Steve spends several pages on the issue of the perpetual virginity of Mary. The issue isn't of much significance in itself, but becomes more significant in light of the claims some groups, like Roman Catholicism, make about subjects like tradition and church infallibility. It's also a significant issue in that there's a common perception that the historical record leans heavily in favor of the doctrine. We often hear of how large numbers of church fathers and other prominent figures in church history, including Protestant reformers, believed in it.
In reality, however, the doctrine is an illustration of the fact that what the earliest generations of Christians believed sometimes conflicts with what later generations believed. Focusing on later church history, while ignoring or neglecting earlier sources, leads to a distorted conclusion. Steve discussed the most significant evidence in detail, and I won't be repeating everything he said. I would second his recommendation that people read the work of Eric Svendsen on this issue, as well as the work of Roman Catholic scholars like John Meier. As Steve's citation of Meier illustrates, and as Eric Svendsen's work documents in more detail, the Biblical evidence not only doesn't support the doctrine, but even leans heavily against it. The other first century source we have on the subject, Josephus, also contradicts the doctrine, as John Meier mentions in Steve's citation.
Something Steve doesn't directly address, however (though it's addressed indirectly through his recommendation of Eric Svendsen's work), is evidence against the doctrine in early post-apostolic sources. Just as some readings of the gospels and other New Testament documents are more probable than others, the same is true of the writings of later sources. If we don't begin with the assumption of a tradition of the perpetual virginity of Mary, then sources such as Hegesippus and Tertullian read more naturally as having rejected the concept than as having accepted it. See, for example, Eric Svendsen's discussion of such sources in his Who Is My Mother? (Amityville, New York: Calvary Press, 2001).
Proponents of the doctrine often point to Jerome's work against Helvidius, an opponent of the doctrine, as an illustration of how the early church believed in the perpetual virginity of Mary and considered opposition to it unacceptable heresy. Yet, the sources Steve discusses and the ones I've mentioned above (Matthew, Mark, Luke, John, Paul, Josephus, Hegesippus, etc.) predate Jerome by a century or more. And while Jerome reacted to Helvidius in a highly negative manner, a contemporary of Jerome took a different approach. Basil of Caesarea commented that the view that Mary had other children after Jesus "was widely held and, though not accepted by himself, was not incompatible with orthodoxy" (J.N.D. Kelly, Early Christian Doctrines [San Francisco, California: HarperCollins Publishers, 1978], p. 495).
Update on 11/27/14: Here's a post discussing more early opponents of the perpetual virginity of Mary.