The "shrillness as an indicator of weakness" fallacy
Twice in the last couple of weeks I've come across cases of people inclined to give credence to a fringe theory - in one case "intelligent design", in the other the Oxfordian theory - on the grounds that the orthodox reply to each is "shrill" or "hysterical".
Of course they're not arguing that this is dispositive evidence on the question (the biggest argumentative fallacy of all, one which I've never seen discussed, but would trash thousands of pages of denunciations of "logical fallacies" if anyone did, is mistaking your opponents' suggestive probabilities or triage to ignore the absurd as attempts at logical proofs). What they are saying is that a shrill response suggests that the opposing side has hit you a good one and that jumping up and down in fury is an attempt to hide the absence of a better answer.
But in both these cases, that assumption is completely mistaken, so it shouldn't be assumed to be helpful in other cases either. The shrillness of the orthodox response to both those theories is actually a result of:
1) Exasperation at how totally ridiculous they are to anyone who actually knows the subject;
2) Weariness at having extensively rebutted them over and over again, and finding that they still haven't gone away.
If you find that the orthodox response to a fringe theory is shrill and unsubstantive, make sure you check around, because the extensive and substantive arguments are probably already there, in some other source.