Appeal to ignorance from an appeal from ignorance?
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Original Question
What type of fallacy is this:
Two "experts", one from domain A (say expert X) and the second from domain A+B (say expert Y).
Assume both experts are equivalent in domain knowledge from domain A. The second expert Y introduces knowledge from domain B to the first expert X. The first expert X denounces the knowledge because he is unaware of that domain B and therefore knowledge from domain B.
X declares this denouncement into a forum likely full of people with only knowledge from domain A and very likely with less domain knowledge than either expert X and Y in their knowledge of domain A.
The use of the denouncement is to undermine expert Y in their domain A expert role. I intimates knowledge of domain B is also indication that expert Y must clearly be less of an expert than X for not recognising that the knowledge from domain B is "new" and untested - clearly because expert X has not heard of domain B.
It is almost a collision of:
Appeal from Ignorance (X: I don't know domain B so it cannot be important)
Appeal from authority or is it appeal to ignorance or both (X: I am the domain expert in A over other practitioners in domain A and my guidance is I do not know domain B and therefore you must also not know domain B)
Ad Hominem(X: you are clearly "dum" for talking to domain B)
If it helps, the domain is C=A+B, expert X has a narrow view of domain C.
Answers
2I appreciate your making this as general as possible to avoid bias, but it can get confusing without an example. Let's use the flat earth (I don't think we have any flat earther's on this forum).
FlatTony24 is an expert in flat earth nonsense. Dr. Science is also an expert in flat earth nonsense, as well as astrophysics. FlatTony24 rejects Dr. Science's views on astrophysics because FlatTony24 knows nothing about astrophysics. FlatTony24 then posts on the Flat Earth forums how he rejects this information. The readers of the forum respect FlatTony24 because of his expertise in flat earth nonsense and therefore also reject the astrophysics of Dr. Science.
Do I have it right? Assuming I do, here are the problems I see:
This is an Argument from Ignorance . FlatTony24 has no evidence that Dr. Science's views on astrophysics are wrong, yet he rejects them (I am assuming that is what is meant by he "denounces" him). FlatTony24 would also be guilty of Poisoning the Well . The readers of the forum would committing the Appeal to False Authority by accepting FlatTony24's views as authoritative when it comes to the rejection of the data related to astrophysics.
"Assume both experts are equivalent in domain knowledge from domain A. The second expert Y introduces knowledge from domain B to the first expert X. The first expert X denounces the knowledge because he is unaware of that domain B and therefore knowledge from domain B"
This is an Argument from Personal Incredulity Fallacy. Expert X cannot believe expert Y's knowledge, therefore expert X concludes, without any reason besides he or she cannot believe or refuses to believe it, that the knowledge is false or improbable.
"The use of the denouncement is to undermine expert Y"
This is a poising the well fallacy. Adverse information (be it true or false) about expert Y is presented. Therefor, the claims of expert Y will be false.
"the knowledge from domain B is "new" and untested - clearly because expert X has not heard of domain B."
This is merely a false assumption, most likely made from a cognitive bias of some sort. It can also fall under the Argument From Personal Incredulity as well. Expert X is acting from ego, trying to hold onto the agenda of keeping his flock and position of authority.
Like Dr. Bo said, the audience on the forum of expert X would be committing a False Authority Fallacy regarding astrophysics.
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