From: bobb@tekig1.PEN.TEK.COM (Robert W Bales)
Newsgroups: talk.origins
Subject: Response to Michael Simon, part 1
Date: 17 Dec 92 21:34:00 GMT


This response covers some of the same area as my response to Bill Jefferies,
However, much of it is from a different angle.  I will divide this response
into a number of postings.  References in the last installment.

Michael Simon writes:

>> me

>>In other words, I gave examples of processes which could cause isocrhons to
>>agree.  And examples of processes which could cause isochrons to agree form,
>>*by definition*, an explanation for how they could agree.

>You did no such thing.  You (vaguely) mentioned some processes which make
>NON isochron methods shakey

Pardom me.  But references to textbooks and journals in which scientists
referenced by name describe the results of dating measurements and describe
why those results are known to be wrong  are not "vague mentions."  They are
verified scientific data.

>in the absence of correlation.

They are not "shakey because of the absence of correlation."   They are
"observed to, at times. give incorrect results."

>You gave ZERO instances of "processes" that could cause a false isochron.

This is not so.  I have quoted the following reference before [1]:

     "It is possible, of course, that the common element bias is
     negligibly small, but this is a matter requiring demonstration
     or convincing rationalization in each specific case.  That the
     denominator may perhaps be serving only as a convienient scaling
     device provides no escape; use of an uncorrelated scaling
     variable whose varience is sufficiently large will impose strong
     positive correlation on *any* pair of variables whose negative
     correlation is less than perfect.  That the scaled data cluster
     closely about a regression line is then mearly a consequence of
     the choice of scaling variable and says nothing about the nature
     of the relation between the variables being scaled."  (page 1234)

The second time I quoted this was in the posting to which Michael is
responding!  I have discussed this also in my response to Bill Jefferies.
Bill does not think this does cause false isochrons.  This is debatable, but
at least it *could*.

Following my suggestion in my preliminary post, I thought about it and
decided that maybe  I did not provide enough background, especially the second
time I posted this.  The "common element bias" and "the denominator" in the
quote refer to the fact that in at least some isochrons (the Rb-Sr and Ni-Sr),
the denominators of the two ratios plotted are the same or closely related.
The result, according to the author, can be the presence of a valid-appearing
isochron line (which, according to many in  this group, is an internal
verification of correctness) when the isotope measurements *have no
correlation.*

This is a definite, non-vague example of what Michael says I have not given!

>You simply left a dangling hope that maybe in some fantastically
>inconceivable world such a thing might be possible (a fantastic possibility
>for a single kind of isochron

Another reference I gave, though not in the posting to which Michael is
responding is [2]:


    "One serious consequence of the mantle isochron model is that
    crystallization ages determined on basic igneous rocks by the
    Rb-Sr whole rock technique can be greater than the true age by
    many hundreds of millions of years.  This problem of inheirited
    age is more serious for younger rocks , and there are well-
    documented instances of conflicts between stratigraphic age and
    Rb-Sr age in the literature." (page 1093)

So we see that the "dangling hope" is actually "well-documented" cases in the
literature, the "fantastically  inconceivable world" is the one we live in, and
the "fantastic possibility" has been observed

>and absurdly inconceivable for multiple isochrons of different elements.)

Please state a probability threshold below which something is absurdly
inconceivable -- which I define as having a probability so low that we don't
need to consider it -- and also the evidence leading to the calculation of the
probability.  Without this, the phrase "absurdly inconceivable" has (as is
pointed out when anybody makes a similar staement regarding abiogenesis) no
scientific meaning.

>In fact, you have yet to exhibit in public any UNDERSTANDING of what an
>isochron is,

I have disussed what an isochron is and the theory behind the claims made
regarding isochrons.  Not agreeing with the claims is completely different
from not understanding them.

>and WHY it is self-checking about its results

I understand why isochron theory claims an isochron is self-checking.  But
there can be a big difference between what a theory claims and what reality
is -- particularly when the claim is contradicted by direct observation.

>(a matter well handled by several summaries here in recent years, notably
>one by Bill Jefferies.)

Which I have discussed in another series of postings.

   Bob Bales
   Tektronix, Inc.

I help Tektronix make their instruments. They don't help me make my opinions.
Newsgroups: talk.origins