Half of a Debate about the Existence of Jesus

Joe Hinman has requested that I debate him about the existence of Jesus, and I have agreed to do so.
We will not, however, attempt to answer the BIG question: Did Jesus exist?  But we will be arguing about a significant issue closely related to that question:
Does the external evidence warrant the belief that Jesus existed?
The phrase “external evidence” means evidence other than evidence from the Bible.  So, we are excluding the internal evidence from the four canonical Gospels, from Acts, from the letters of Paul, and from the other writings in the New Testament.  Thus, this is only “half” of a debate, since we are only going to be discussing “half” of the evidence.
Joe Hinman will argue for the claim that the external evidence warrants the belief that Jesus existed.
I will raise objections and point out weaknesses in Hinman’s evidence and arguments for that claim, in an effort to show that the external evidence presented by Hinman does NOT warrant the belief that Jesus existed.  I will NOT be arguing that “Jesus is just a myth”.   So, if Hinman “loses” the debate, that does not mean that I will have shown that Jesus is a myth.  In fact, if Hinman “loses” the debate, that does not mean that there is no good evidence for the existence of Jesus,  because even if there is no solid external evidence for Jesus, there could still be solid internal evidence (i.e from the Bible) for Jesus.
Similarly, if I “lose” the debate, that does not mean that Hinman will have proved that Jesus existed.  Hinman has quite reasonably set out to achieve the more modest goal of showing that the external evidence is sufficient to warrant the belief that Jesus existed.
I take it that by “warrant” Hinman means something less than possessing the sort of justification that is required for KNOWLEDGE (something less than what Plantinga means by “warrant”).   I take it that Hinman is simply trying to show that the external evidence is sufficient to make belief in the existence of Jesus reasonable.  In terms of probability, I think that means showing that the existence of Jesus is somewhat probable, at least more probable than not.  Knowledge of the existence of Jesus would require more than this; it would require showing that it is (at least) highly probable that Jesus existed.  Hinman is not trying to show that we can KNOW that Jesus existed based on just external evidence; he will try to show that the external evidence is sufficient to make it somewhat probable, at least more probable than not, that Jesus existed.
If Hinman is successful, and “wins” this debate, that would not be a great blow to me, because I’m currently inclined to believe that is it more probable than not that Jesus existed.  Hinman is making a fairly weak claim here, making a claim that is much more reasonable than the extremely strong claims made by Paul Maier (see my post criticizing Maier’s apologetic essay on the existence of Jesus).
However, I am unimpressed by the external evidence for Jesus, so I think I have a decent chance of “winning” this debate, or at least of making it difficult for Hinman to make his case.  In the debate with Hinman, I plan to take the role of a defense attorney who argues that the prosecution has failed to meet its burden of proof.  My focus will be on pointing out problems and weaknesses in Joe Hinman’s case.
But I will now make a very brief positive argument for my position, in order to indicate that there is some reasonable hope that I could “win” this debate, in spite of the fact that Joe Hinman only needs to establish a fairly weak claim in order for me to “lose”.
One of the leading Jesus scholars of the 21st Century is on my side, at least to a large degree.  The conservative Jesus scholar N.T. Wright makes the following comments about John Meier’s multi-volume work A Marginal Jew: Rethinking the Historical Jesus:
Massive study with roots in modern…methods of criticism, and results that are substantially conservative.  Will be widely used and discussed for years to come.  (The Original Jesus, p.155)
The leading N.T. scholar Pheme Perkins praised the first volume of Meier’s books on the historical Jesus:
This book is a wonderful example of judicious historical scholarship.  It should be required reading for all historians, pastors and theology students.  (from the back cover of A Marginal Jew, Volume 1)
Paul Achtemeier, a widely respected N.T. scholar and the general editor of the Harper Bible Dictionary, also gave a very positive evaluation of Meier’s work on the historical Jesus:
By his painstaking research, his balanced presentation, and his sane conclusions, Meier has set a new standard against which all future studies of this kind will have to be measured. (from the back cover of A Marginal Jew, Volume 1)
John Meier devotes four chapters of Volume 1 of A Marginal Jew (chapters 2, 3, 4, and 5) to a careful, scholarly review of the various historical sources that are thought to be relevant to the investigation of the historical Jesus (pages 41-166).  Here is one of his most important general conclusions based on this careful review of potential historical sources about Jesus:
For all practical purposes, then, our early, independent sources for the historical Jesus boil down to the Four Gospels, a few scattered data elsewhere in the NT, and Josephus. (A Marginal Jew, Volume 1, p. 140)
Out of all of the various external sources that Meier carefully reviewed, he believes that there is only ONE EXTERNAL SOURCE that is early and independent: the Jewish historian Josephus.
If Meier is correct that all of the other external sources are late or dependent (either directly or indirectly) upon Christian writings, or problematic in some other way, then the only potentially significant external evidence for Jesus are the two famous passages in the writings of Josephus that mention Jesus.  If this evidence from Josephus turns out to be weak or dubious, then it appears to Meier and to me that the external evidence for Jesus is NOT sufficient to make the existence of Jesus more probable than not.
Although Meier is impressed by the external evidence from Josephus, other NT scholars are not so impressed.  A respected NT scholar named Robert Van Voorst wrote a widely-used book about the external evidence for Jesus.  In that book, he arrives at a conclusion that is similar to that of John Meier, but less confident about the Josephus evidence:
In sum, Josephus has given us in two passages something unique among all ancient non-Christian witnesses to Jesus: a carefully neutral, highly accurate, and perhaps independent witness to Jesus… (Jesus Outside the New Testament, p.103-104)
Note that Robert Van Voorst does NOT claim that the Josephus references to Jesus are certainly an independent witness to Jesus, nor does he conclude that these references are almost certainly an independent witness to Jesus,  nor does he assert that they are very probably an independent witness to Jesus,  nor does he say that they are probably an independent witness to Jesus.
Robert Van Voorst is no mythicist.  He clearly supports the view that Jesus existed.  But after a careful review of non-Christian external evidence for Jesus, he concludes that the two passages from Josephus are the very best evidence for Jesus in that category, and yet he can only bring himself to claim that these passages are “perhaps independent witness to Jesus”.   I am not impressed by this rather weak conclusion.
Bart Ehrman is a bona fide NT scholar who has written extensively about the historical Jesus, early Christianity, and the Gospels.  Ehrman wrote a book devoted to the question “Did Jesus Exist?” and one of his conclusions was that the famous references to Jesus by Josephus are of little or no historical significance:
…even though the mythicists and their opponents like to fight long and hard over the Testimonium of Josephus, in fact it is only marginally relevant to the question of whether Jesus existed.  (Did Jesus Exist? p.66)
Ehrman views the Josephus references to Jesus as being “only marginally relevant” because he doubts that these passages in Josephus are independent from Christian stories and writings about Jesus:
Whether or not Jesus lived has to be decided on other kinds of evidence from this.  And here is why.  Suppose Josephus really did write the Testimonium.  That would show that by 93 CE–some sixty or more years after the traditional date of Jesus’s death–a Jewish historian of Palestine had some information about him.  And where would Josephus have derived this information?  He would have heard stories about Jesus that were in circulation.  There is nothing to suggest that Josephus had actually read the Gospels (he almost certainly had not) or that he did any kind of primary research into the life of Jesus by examining Roman records (there weren’t any).  But as we will see later, we already know for lots of other reasons and on lots of other grounds that there were stories about Jesus floating around in Palestine by the end of the first century and much earlier.  (Did Jesus Exist? p.65)
Ehrman has left the Christian faith and no longer believes that Jesus was God incarnate, but he is not a mythicist.  Ehrman strongly supports and defends the view that Jesus really existed.  So, Ehrman’s low opinion of the Josephus evidence is not motivated by a desire to cast doubt on the existence of Jesus.  A more positive view of the Josephus passages would have helped Ehrman make his case for the existence of Jesus.
So at least two respected N.T. scholars doubt that the references to Jesus by Josephus represent independent information about Jesus.
According to one of the leading Jesus scholars of the 21st Century, the only external evidence for Jesus that is potentially significant is the evidence from the Jewish historian Josephus.  But according to at least two respected NT scholars, who have studied this issue, the two references to Jesus by Josephus are of very doubtful independence from Christian stories and writings, including (indirectly) the canonical Gospels.  Doubts about the independence of the Josephus passages render this evidence weak and insignificant, not to mention issues with the text of the Josephus passages.
If we combine the doubts about the text of the Josephus passages (it is very clear that at least one of the passages was tampered with by Christian copyists) with the (more significant) doubts about the independence of these passages, the result is that the Josephus references to Jesus provide evidence that is too weak to justify the claim that “Jesus exists” is more probable than not.
Assuming that the Jospehus references to Jesus are the very best external evidence for Jesus, and that other external sources for the existence of Jesus are either too late or are dependent on Christian stories or writings, or are problematic for other reasons, we can reasonably conclude that the external evidence for Jesus is NOT sufficient to warrant belief in the existence of Jesus, that it is NOT sufficient to make the claim that “Jesus exists” more probable than not.