Darth,
I agree with you that Stem thinks the witness statements in the Book of Mormon gives support for J. Smith's claims..and he thinks it is strong support/evidence. He does understand though that they lack the expertise to determine if the plates were ancient and expertise to determine and/or know if Smith actually translated plates. He also I believe has indicated that he appreciates data/evidence on its own may not be useful but along with other evidence helps to support a best fit theory. Of course though he is not very objective in evaluating the evidence.
If he gets the point, why is he still asserting that the unfounded statement of Joseph Smith's dad et al. is circumstantial evidence that the Book of Mormon is true?
He is not objective and does not evaluate the evidence well. That's no surprise coming from a believing Mormon.
Here is something Craig Criddle has written on evaluating evidence:
http://sidneyrigdon.com/criddle/rigdon1.htm
The formulation of evidence-based narratives is subject to many kinds of uncertainty, starting with the facts themselves. Measurements and records have limited accuracy. The material world decomposes, so information is lost over time. And then there's the human factor. Evidence can be mishandled or destroyed. Memory and perceptions are fallible and can be manipulated. Eyewitness accounts are much less reliable than generally believed.
Uncertainties force us to deal in probabilities in assessing past and present reality. The challenge comes in assigning values to those probabilities. For example, how likely is it that Joseph Smith spoke with God and translated The Book of Mormon from plates of gold? Devoted and thoughtful Mormons will feel that they have adequately reviewed the evidence and are justified in believing to a probability of near 100% that these events occurred. Virtually all non-Mormons who have reviewed the same evidence conclude that the probability is close to 0%. We can learn a lot from a careful examination of the reasoning processes that different groups use to answer the same question.
>>>
We are far from rational information processors. We have biases and suffer from cognitive dissonance induced denial. The best defense against denial and other biases is the kind of peer review used by the scientific community. The idea is to find a group of well-informed individuals who can act as an "objective" forum of critics -- the larger and more diverse, the better. That is because a diverse group will tend to spot, critique and nullify each other's error and bias, while drawing attention to other relevant information.
Scientific inquiry is like a dot-to-dot puzzle, where the dots themselves have to be uncovered in some way. Each dot is a piece of evidence or data. The idea is to reveal as many dots as possible, then connect them as simply as possible. Data that seem clear are dark dots, whereas uncertain data are faint. When only a few faint dots are available, the picture is unclear. But as the dots accumulate, and become darker, a relatively reliable pattern often emerges. The more testable the pattern and more replicable the results of experiments designed to test it, the more reliable the pattern is. The peer review process seeks to ensure that the dots are shaded and located correctly and then connected using short straight lines so that the overall picture is interpreted correctly.
Using Craig's dot analogy, you look at the witness statements as one dot shaded in support of a best fit theory of a hoax and as not being evidence at all in support of Smith's claims to ancient plates, assuming he actually had plates which is still debatable. He looks at the witness statements in the Book of Mormon as darkly shaded in support of Smith's claims.
I agree with your evaluation.