> In common with most other readers (apart from you,
> apparently), I am obliged to accept what an author
> has to say about the sources of his evidence, and
> support for his theories).
First of all, surely there is no possible way you could know what "most other readers" have in common in that regard.
Secondly, I still don't understand what bearing Jon's expertise has on the validity of his descriptions or why anyone would want to know more about his background based on the observations he made.
When an author claims this or that statement is based on a source whose expertise is <stated expertise> all that signifies to me is the tool used by the source as inspiration for the information presented. It makes no difference to me that the Edgar brothers or Adam Rutherford were inspired by the Bible to report their observations. The observations should be judged on the merit of the evidence presented and not the expertise from which the insight stemmed for making those observations.
In this case we are simply being told that Jon's art expertise is what facilitated his observations, observations which any of us are quite able to verify. How that would prompt any reader to want to know more about Jon's expertise before "trusting" his observations makes no sense to me.
I think you are trying to force a point that simply doesn't apply here. As I said, even if Jon lied to Scott about his expertise, it won't change the observations he made about the brush strokes, and won't change the readers' ability to verify whether Jon's observations correspond to the brush strokes seen in those high quality photos.
> GPH readers will doubtless read what the author
> has to say, and then might feel obliged to enquire
> further about the qualifications of the art expert
> whose expertise Creighton has cited. In this
> case, Mr. Creighton has stated that John Snape is
> an "art expert."
I doubt that any objective reader would "enquire further" simply because I see no information to be gained from such knowledge that would add to the brush stroke descriptions Jon offered. Besides, the author of a book is under no further obligation to elaborate on what's published in the book. The book archives are sealed and must be taken on the merit of what's published. If the author thought more information was warranted, it would have been included in that edition of the book. If you think Scott should have included more information about Jon before you give Jon's observation more credibility then let that influence your choice about whether to buy the book. But logically, getting any more information about Jon's expertise is inconsequential to our ability to corroborate whether Jon's descriptions do indeed correspond to the paint brush marks we see up there in the rafters.
> But John Snape's achievements in this field are a
> completely separate matter from what he makes of
> the quarrymarks in Campbell's Chamber. So merely
> pointing enquiring readers back in the direction
> of John Snape's pronouncements on the quarrymarks
> in Campbell's Chamber is really rather missing the
> point ...
Then I guess I missed your point. The only thing relevant about Scott including Jon's comment is his "pronouncements on the quarrymarks in Campbell's Chamber". Jon's expertise is otherwise irrelevant except for the fact that it facilitated the insight to make those observations in the first place. And the proof is that completely omitting Jon's expertise changes nothing about the observations he made.
How can any of us ever know, when all we can do is think?