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orion-list Radiocarbon discussion

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Sigrid's point on the issue of provenance makes a point well 
worth considering.  There are these 19 radiocarbon dates on 
texts with 4Q numbers (except for three 1Q texts).  It is worth 
being reminded that of the two dates farthest out at either end 
which are widely rejected, i.e. 4QTQahat (4th-3rd BCE) and 
the first measurement of 4QS(d) (2nd CE), there is no evidence 
that those datings were affected by contamination, or incorrect 
measurements of those texts.  Orioners who have been
following radiocarbon issues with the Scrolls might conduct a
mental exercise: (a) in your personal interpretation of the data,
do you regard the two dates just cited as reflecting the accurate
true dates?, and (b) if not, why?

In my Flint & Vanderkam article (1998) I went through these texts.
I did argue that both of those appear to be inaccurate.  However,
a careful reader will note my reasons were not the same reasons
that most in the Qumran field give in arriving at the same conclusion.
In the case of TQahat, the usual view is that TQahat's date is
incorrect due to a disagreement with palaeographic dating (i.e. a
data point excluded on the basis of another hypothesis).  For example,
Cross 1995 (Anc. Lib.): 174n1, "A wrong result was produced in one
instance among the fourteen documents tested [at Zurich]: the 
Testament of Qahat [4Q534] . . . the carbon14 for the Testament of
Qahat is 388-353 BC [sic], an impossible dating, some two centuries
too early."  

A second reason many might give for questioning the 4QTQahat 
date was cited by T. Jull in his post, namely that the Zurich lab found
signs of contamination both times in separate examinations of two 
samples from 4QTQahat (_Radiocarbon_ 34, 1992: 843-849).  
However, I believe Jull may have erred in referring to this data as 
suggesting some problems with the pretreatment done by Zurich.  
Nothing in that data appears obviously to call for such an interpretation, 
nor was that the interpretation of the Zurich lab of this data (see the 
Radiocarbon article for details).  The Zurich Table 2 measurements 
only diagnosed the presence of contamination before cleaning 
(pretreatment), not after cleaning (pretreatment).  There is no evidence 
from any Zurich data that the cleaning did not work or should not be 
expected to have worked as it was supposed to.  It was this example 
of 4QTQahat to which Jull referred in his remark about not excluding 
data points on the basis of some other hypothesis.  (Jull was not 
referring to 4QpPsA with that remark.  I am the one who made the 
connection of Jull's statement in my discussion of 4QpPsA in a 
subsequent post.)   

In my analysis of 4QTQahat, I did not rely on palaeographic dating 
as of any weight.  I cited two other reasons for questioning that C14
date.  First, it is way out at one end of the total distribution. And 
second, it does not agree with another text of same genre, same 
type of scribal hand (4QTLevi)--which I reasoned almost must be 
contemporary.  (In the same way, I reasoned that 1QpHab and
4QpPsA should have given coeval radiocarbon dates--but they
did not, leading me to the serious strong sense that something
in that discrepancy is not as it should be, and bears further 
investigation, for that single reason.)

Therefore I concluded, in agreement with the conclusion of most
in the Qumran field but by a different method of reasoning, that
4QTQahat's date is suspect, and does not appear right.  Is this 
rejection of a data point on the basis of some other hypothesis?  
Yes or no, depending on how one views it.  In any case, there is 
no certainty on this.  That 4QTQahat date, in principle, could be 
accurate.  (A late 3rd BCE date for that text, which would be within 
the 2-sigma range, is not a priori impossible.)  On the other hand, 
if it is not accurate, contamination is simply what appears the 
likely explanation (in light of the diagnosis before cleaning).  But 
that is simply an inference; there is no test that ever corroborated 

In the case of the 4QS(d) 2nd century CE date (first sample),
what are the reasons for considering that date incorrect?  And
if so, for concluding that contamination is the reason for that 
error?  In fact, there is no other sound reason for excluding that 
data point (and preferring the earlier dating of the 2nd sample) 
than the hypothesis that it is "too late" compared to the other 
text datings, and on that grounds alone is suspicious, and 
perhaps affected by contamination.  But none of this is certain.  
There are other hypothetical possibilities: (a) as Sigrid suggested, 
the first sample of 4QS(d) was dated accurately but 4QS(d) is 
not from Qumran, even though we in the Qumran field think it 
is.  (b) a mistake in handling occurred at some point in which 
a Bar Kochba era fragment was dated accurately, but mistakenly 
identified and reported as a date for 4QS(d).  (c) the Qumran 
cave deposits, surprisingly, do contain texts up to the 2nd 
century CE.  However, there is still (d) unremoved sample 
contamination produced an erroneous date.

Which of these is the truly correct explanation, and how does 
one know?  In these cases, perhaps we may never know for 
sure.  How does one rationally justify excluding either of the 
two data points at either end without being charged with 
arbitrary exclusion of datapoints on the basis of some other 
hypothesis?  But if 4QTQahat and the first sample of 4QS(d), 
at either end of the total distribution of Qumran text datings, 
are not excluded, what does that do to conventional theories?  
In the end, the closing words of Jull are the way forward: 
"There is in such things no substitute for more measurements, 
which if they agree allow us to reduce the error, and if they 
do not, should tell us that there is some problem."  

Greg Doudna


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