As everyone knows, it is illogical to say that a proposition is false because of some trait or characteristic of the person espousing the proposition.
For instance, it is illogical to say that “chickens are birds” is a false proposition because the person who said it, Jones, happens to be crazy. Even though it might be true that Jones is crazy, the proposition logically stands or falls on its own merits, rather than the merits of the person espousing it.
Now that’s all very fine and dandy, but that rule applies to formal or deductive logic. The rules are a bit different in informal or inductive logic. So, is there ever a time in informal logic when the merits of the person asserting the proposition do indeed become relevant?
Please consider, in informal logic, an argument from authority is logically valid provided that the authority is relevant. If the authority is irrelevant, then an argument from authority becomes illogical or fallacious.
For example, it is usually a valid argument from authority to cite Einstein on the Theory of Relativity, since Einstein was an authority on the subject. But it would most likely be an invalid argument from authority to cite Einstein on the subject of ancient Phoenician blue glassware since Einstein was no authority on the subject. Thus, you can have both valid and invalid arguments from authority.
But, if you can have a valid argument from authority, can you have a valid argument from anti-authority? That is, if you can establish that Jones is more often wrong than right on a particular topic, can you logically cite Jones as an anti-authority?
Example: Jones is wrong most of the time about chickens. Jones says chickens are lizards. Therefore, chickens are most likely not lizards.
Would that be a logically valid argument?
Why or why not?