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orion-list 63 BCE/ radiocarbon (Pt. 1)

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Stephen Goranson wrote:

> 	It seems to me that C14 has already excluded--at least, practically
> speaking--the proposal that all Qumran mss were deposited in 63 BCE. Five
> manuscript date ranges are fully afterward. Greg Doudna referred us to a
> footnote he wrote, which does raise the question of possible contamination
> by castor oil (p449 n44). Yet that same note endorsed use of acetone
> cleaning. Four texts were so cleaned. And two of those, thus cleaned, are
> among the totally after 63 date ranged ones (4Q266 D; 4Q258 Sd). So even
> when the test followed his preference, he still rejected it. 
> 
The problem is that the first sample of 4QS(d) gave a 2nd-3rd century
CE date, and, n.b., that first sample _was cleaned with acetone_.  
Either that date is accurate or else the acetone cleaning was not
sufficient.  If that is not enough to call into question the efficacy of
the existing use of acetone I don't know what is.  In the latter case--
if the acetone cleaning was not sufficient to accomplish full cleaning--
this calls into question the confidence we can grant to the other datings
of samples cleaned by acetone in the same way.  In the case of 4Q266,
the second youngest text dated of the 19 Qumran texts total, this text
was considered "almost certainly" pre-63 BCE by Cross on palaeographic
grounds.  I leave it to Goranson to decide whether the acetone cleaning
or Cross's palaeographic dating is more likely flawed in the case of 4Q266.
What I say is: because the situation with 4Q266 is exactly parallel to the
first sample of 4QS(d) which gave the anomalous 2nd-3rd century CE
age--visible glue and treatment with acetone--the date on 4Q266 must
be regarded also with suspicion pending further data.  See my discussion
forthcoming in Kapera, which is actually that to which I referred, not the
p449 footnote alone.  In the Kapera article I note that although the use
of solvents is in principle correct, the use of acetone alone apparently
is simply not enough (on the evidence of 4QSd), and it may be a greater
range of solvents is indicated, which only experiments can determine.

I would like to emphasize again that all of these observations are in
the nature of soluble, no pun intended, problems, as distinguished from
insoluble problems; further, that the Tucson lab, one of the most well-
financed labs in the world, is in an excellent position to do the kind
of research on effective pretreatment technique modifications to bring
about a state of confidence in individual Qumran text radiocarbon datings.
However, research on these problems continues here in Copenhagen, and
the scientific publications in the works on this should prove interesting
and useful.

[Goranson] 
"So even when the test folflowed his preference, he still rejected it."

[Doudna] 
I do not accept the characterization that I have rejected those two dates.
Rejection means one has a reason to know they are wrong, and I don't
know that or claim that.  The accurate statement is I am not yet
accepting them.  Acceptance means one has reason to know they are
correct, and I don't know that either.  Rather than acceptance or rejection,
this is a third category: "uncertain, and needing further study in order
to understand".  I trust most readers of the list will try to understand my
point here, even if some have difficulty grasping it.  The key point is
there
are three, not just two, categories for evaluation of data: presumed true,
presumed false, and no presumption/uncertain (live questions).  I put the
five clearly post-63 BCE datings in category #3, rather than #1, for
reasons explained in the Kapera article.

> Further, all
> but one of the remaining test date ranges straddle 63 BCE. So one would
> have to expect every one of these also to fall before 63. Isn't that a lot
> to ask?
> 
Due to the shape of the calibration curve, any text with true age
from 85-63 will also show possibility, on radiocarbon grounds, for
a date at least as late as 55-50 BCE.  (And in my theory, a large
number of Qumran text scribal copies indeed date from 85-63, so
the consideration is not simply hypothetical.)  This is because the
calibration curve is "flat" between 85-55 BCE, i.e. C14 levels the
same in that period.  That is simply an accidence of the way it it
for those years as measured in tree-ring studies.  One cannot 
draw conclusions of any kind concerning which date inside the
85-55 BCE range is more probable, individually or cumulatively,
no matter how many texts give this kind of overlap of 63.  Five
thousand texts all from true age 85 BCE will give the same
radiocarbon datings as five thousand texts all from true age 55 BCE.
One can only date items with more precision inside the range
85-55 on the basis of toher information extraneous to radiocarbon.
If this seems puzzling ask Tim Jull for more elaboration on this 
point.  Another way of looking at it is radiocarbon doesn't in
principle tell you when the true age is; it tells you when the true
age isn't.  (continued)

Greg Doudna

For private reply, e-mail to Greg Doudna <gd@teol.ku.dk>
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