Shroud of Turin -- is it absolutely and definitively debunked?

Question

A little context on this famous myth:

The Shroud of Turin or Turin Shroud is a linen cloth bearing the image of a man who appears to have suffered physical trauma in a manner consistent with crucifixion.
Some contend that the shroud is the actual cloth placed on the body of Jesus Christ at the time of his burial, and that the face image is the Holy Face of Jesus, while others contend that the artefact was created in the Middle Ages, as indicated by carbon dating which placed the artifact between 1260 and 1390.

Now, the JREF claims that this particular myth is absolutely debunked. I completely agree that the shroud has not, and will never, be proven to be a genuine holy item - how could one prove that it was used on Jesus of Nazareth at all?

On the other hand, the way the myth is debunked is, in my view, flaky, weak and unconvincing. Here in short are the claims, after each my doubts:

• The cloth itself could not date from the correct period or from that area of the world, simply because that particular weave of cloth was not made then or there.

  I cannot find any good source to verify this. In any case I don't see how we can easily make such assertion (it could be an uncommon type with few examples left).

• Wrapping of a body in that size and shape of cloth was not done in Palestine at that period. Such wrapping disagrees with the biblical description as well.

  This is completely irrelevant - either the cloth is from that place and time or it isn't. It could have been an unusual choice.

• The representation of the face of Christ on this cloth and in all paintings and sculptures is and always has been a formalized guess. This version matches the “accepted” one. We know nothing about Christ's actual appearance.

  This is also totally irrelevant - the fact that Jesus has been depicted as a hippy guy with a beard does not rule out or confirm anything about his appearance (if he existed).

• Carbon dating of the fabric, done in three independent labs, showed that the linen fabric was woven about the year 1350.

  True, but there are claims that the results might have been obtained by medieval repairs instead that from an original part of the cloth. The areas that have been cut off were the worst kept in order not to destroy important parts of the cloth.

• The “bloodstains” are not only red in color (they could not be, after that period of time), but they were shown by chemical analysis to be paint of the composition used in the fourteenth century.

  I cannot find any real affirmative confirmation of this claim - I can only find claims that someone made paint of the same color as the shroud, but no confirmation that "chemical analysis" has been performed on the shroud at all. Wikipedia, for what is worth, has a totally different story on the matter.

• The bishop of Troyes (Lirey) knew who the artist was who painted the cloth and when and how he did it, and so reported to Pope Clement VII. The document still exists and has been shown to be unquestionably authentic.

  This is shaky evidence - it's hearsay.

The question is the following: Is the JREF correct when they affirm that "Definitive tests prove absolutely that it is a forgery"?

Answer 1

Remember the burden of proof in this case is on the believer to prove that the shroud is genuine, not for the skeptic to prove it a forgery.

The definitive testing of the shroud was done in 1988 by 3 independent laboratories (and possibly verified by a fourth) in Zurich, Oxford and the University of Arizona. You can find the results of the radiocarbon dating done by accelerated mass spectrometry here. The methods for the taking of samples and the treating of results were agreed upon by the three labs, overseen by the British Museum, and approved by the Archbishop of Turin and the Holy See (owner of the shroud). All showed cloth dating from the 1300's.

The findings of these results confirm those done by McCrone, who examined the shroud using electron microscopy in the late 70's and identified the pigment of the shroud as red ochre. His published results are here.

There have been attempts to claim that biological or other contaminants caused a false reading. Those claims are thoroughly refuted here by demonstrating that the 9kg shroud would have to be covered in 40kg of biological contaminants for the reading to be skewed enough for the shroud to be from around 36 C.E.

There have been some claims that the sample was contaminated by fire damage, or water damage (or both, depending on who you read), and there have also been claims that there are "unauthorized, undocumented" repairs through history which resulted in contamination.
here is one such claim, I find it to be particularly weak in light of the above evidence.

This information, should be considered with what is known historically about Geffroy de Charny (possible spelling error there, sorry!) who showed up sometime in the 1350's with the shroud and a desire to build a church (which in those days needed a really cool relic to be a really cool church).

So, there is no definitive historical proof of a named and documented individual who can be proven to have lived in the time period providing evidence showing that he, himself was the creator of the shroud. However, the evidence that is available points to a quite rational, simple explanation. The simple fact is that based on the demonstrable evidence at this time, the shroud does not meet the burden of proof to be considered legitimate.

If you are interested, you can find a list of theories, experiments, hypotheses and studies done over the years by various organizations with various agendas conducted with various degrees of scientific rigor here.

Answer 2

From a full-on mathematical definition of certainty and uncertainty according to probability and information theory, the reality is that most historical questions are only "known" to very low degrees of certainty. As a result, people often do not notice that they have transitioned from discussing what the percentage chance is that event x occurred or that article y is from time period z, to discussing whether evidence against that hypothesis outweighs evidence in support of it; i.e. whether the probability of the hypothesis being true is 50.0001% vs 49.9999% (as opposed to %50 for answer truly unknown).

So if your question is whether there exists a nearly 100% certainty that the shroud is a forgery, the answer is clearly no. But we can say authoritatively that from the available information (listed and referenced extensively on this page already) there is a statistically significant deviation towards the forgery side of the equation, as opposed to the non-forgery or "genuine" side. Most telling is the fact that the entity holding the most information, the Vatican, prefers to emphasise the symbolism of the shroud over its historical nature (which they surely would if they believed there to be good evidence for it). From the pope's recent meditation on the shroud:

...One could say that the Shroud is the Icon of this mystery, the Icon of Holy Saturday...the Turin Shroud presents to us an image of how his body lay in the tomb during that period which was chronologically brief (about a day and a half), but immense, infinite in its value and in its significance

For those who venerate the shroud, the significance of this image is probably much more important than the shroud's historical nature.