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Diamond fallacy

  1. Jul 12, 2008 #1
    Interesting publication:


    In normal geology jargon, this means that they are pretty convinced to be on to something. However:

    What they found was depletion of heavy 13C atoms reducing the d13C ratio to values comparable to photosynthesis nowadays as this process favours the lighter 12C atoms, breaking the bonds more easily, I assume.

    However this is a typical affirming the consequent fallacy: "If it snows the fields are white; the fields are white, hence it snows.". Photosynthesis causes depletion of 13C. There is 13C depletion, hence it was photosynthesis. Not that there are many known processes to cause such a depletion.

    On the other hand there are many parts in the carbon cycles with very slight fractination processes that accumulate in all those billion years which may also have caused the intial apparant depletion.

    But interesting.
  2. jcsd
  3. Jul 12, 2008 #2


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    That's why they didn't claim proof. However, this is standard statistical inference -- observing a white field lends more evidence towards hypotheses that suggest white fields are likely than to hypotheses that suggest otherwise.
  4. Jul 14, 2008 #3
    The "life on earth" thing is there to arouse interest. As empirical scientists we should be most interested in the results of their experiment.

    I would disagree with your interpretation that "in normal geology jargon, this means they are pretty convinced to be on something". First off, the quote you have inferred this from is secondary to the actual article itself, what's more, it's not even the words of the researcher. And furthermore, the second quote you have posted (which actually does contain the words of the researcher) weakens your argument, it clearly states (as Hurkyl points out) that "Our data do not prove the existence of life 4.25 billion years ago".

    I wonder, why do you feel the need to challenge here?
  5. Jul 14, 2008 #4
    the challenge is not the researchers, it's about the reporting.
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