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Re: orion-list Radiocarbon
On Fri, 27 Aug 1999 17:39:00 +0200, firstname.lastname@example.org writes:
>Yesterday I cited, in the strongest form I could, the case from
>radiocarbon against a 63 BCE terminus hypothesis. At first blush
>it sounds immediately decisive, indeed virtually airtight: five
>separate radiocarbon dates, of 19 total Qumran texts dated,
>give two-sigma ranges entirely later than 63 BCE, at 95%
>confidence reported by the lab for each one of these datings.
>The reason I do not consider these 5 dates a falsification of a 63 BCE
>terminus hypothesis is simply this: in four of those five cases, the
>edge of the two-sigma range is so close to 63 BCE that it appears
>hairsplitting to claim certainty, in the absence of further data and
>context. E.g. 1QH (47 BCE...), 4Q266 (44 BCE...), 4Q258 #2
>(50 BCE...), 4Q521 (49 BCE...). In only one case is the start of the
>2s range unambiguously and clearly removed from 63 BCE in terms
>of calendar years: 4QpPsA (3 CE...).
Ah, now that's more like it.
>Readers of orion might consider: (a) if you had no radiocarbon data,
>would you know a 63 BCE terminus hypothesis was excluded on
>some other grounds? Can you articulate what those grounds are,
>and how secure they are? And (b) as an analogy and as a mental
>exercise, consider the following calibrated radiocarbon dates for three
>texts and answer this hypothetical question: "Does the radiocarbon
>data below falsify an hypothesis that all of these texts were deposited
>no later than 134 CE?" (Please take time to think this through, and
>form your personal answer, before continuing further. Note especially
>the two sigma range of the second item below.)
> 1sigma (68% confidence) 2sigma (95% confidence)
> 132-324 CE 80-389 CE
> 237-340 CE 140-390 CE
> 131-240 CE 84-322 CE
>In fact this is not hypothetical. These are the radiocarbon dates on
>three Bar Kochba-era texts of known dates, none later than 134 CE,
>that were measured by the same lab and in the same battery that
>produced four of the five apparent post-63 BCE radiocarbon dates
>on Qumran texts, i.e. at Tucson. This example should serve as a
>caution against overinterpretation of the existing data. It should be
>a caution against premature certainty or inappropriate claims of
>what is "probable" and "improbable". The edges of reported 2s
>calibration ranges should be regarded as just a little bit fuzzy.
Well, they certainly confirm the items are from the Bar Kochba
Revolt since that's where they were found. It doesn't show
that they DON'T, for sure.
>The second issue is of course the all-important issue of contam-
>ination. The important points are: (a) there is, distressingly, an
>almost certain occasional incidence of contaminated datings among
>the first two batteries; (b) the actual incidence, while probably not
>high, is unknown, particularly in the Tucson battery (in the smaller
>Zurich battery there are grounds to suppose the incidence may be
>c. 10%); (c) all other things being equal, cases of contaminated
>dates tend to show up at the edges of the total distribution rather
>than in the middle of the cluster.
Wait a minute - are you speaking of DSS text fragments?
>In the Tucson battery some 18 Dead Sea texts were dated. I
>identify at least three cases of suspected contamination among
>these: (1) 4Q258 (1st sample), likely. (2) 4Q345, an economic text
>from Seiyal/Hever, because it gave an unusual 371-171 BCE date
>among otherwise Herodian and post-Herodian economic texts.
>And (3) 4QpPsA, because it disagrees with 1QpHab, which I think
>almost must be contemporary. Please appreciate and believe me
>when I say this analysis of the 4QpPsA/pHab discrepancy is what
>I would think no less strongly even if I believed in a 68 BCE deposit
>date. I realize many do not share this same intuition of a pPs/pHab
>contemporaneity, but to me, it is very strong. The reason for focusing
>on pPs rather than pHab as the suspected problem between the two
>is of course pPs's outlier appearance relative to the total distribution,
>whereas pHab is in the midst of the distribution.
Again, you address nothing of the handling treatment by the
recovery teams and the analysis people. I've heard of some
>Perhaps many or most may agree with me that at least one of the
>above looks contaminated, maybe two, and some may even go with
>me on the suspected third. In none of these cases do we have any
>secure knowledge of whether those dates are or are not contaminated--
>we're groping in the dark. And we don't know the true incidence
>throughout the Tucson battery as a whole. If 2 or 3 of the ones I have
>just cited were contaminated, the true incidence could be a little higher,
>perhaps even another 2 or 3. Not necessarily--but it just is not known.
>For these reasons the 5 apparently secure post-63 BCE dates are
>not secure, in my view, in establishing that any text at Qumran is
>certainly later than 63 BCE. Four of the five dates are only a few
>years away in the start of their 2sigma from 63 BCE, which risks
>interpreting the data overprecisely to claim 63 BCE is certainly
>excluded. The fifth, 4QpPsA, is, by coincidence (and it is
>coincidence), on my personal short list of suspected contaminated
There are no secure records of fragment handlings, are there?
>This is why I do not regard existing radiocarbon data as definitively
>inconsistent with a 63 BCE terminus hypothesis, but instead as
>ambiguous. I do not regard the issue as one of rejection of data,
>but rather what is appropriate to claim as knowledge on the basis
>of existing data. What light future data will shed on the existing
>data of course remains to be seen.
If you had better prospects of getting data clear of contamination
would you be more hopeful?
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