!!'''[[http://en.wikipedia.org/wiki/Fallacy_fallacy The Fallacy Fallacy]]''':
!!! Also called
* Appeal to Fallacy
* [[StrawVulcan Mister Spock Fallacy]]
* Fallacy means Wrong

Claiming that a position must be false because the argument used to get to that position is invalid or used a fallacy. It may sound like a rational thing to do since by definition a fallacious argument ''makes no sense'', and this rule may seem like a {{mindscrew}}y special case, but...

->Tom: All cats are animals. Ginger is an animal. This means Ginger is a cat.
->Bill: Ah, you just committed the "affirming the consequent" logical fallacy. Sorry, you are wrong, which means that Ginger is not a cat.

Bill's rebuttal is an argument from fallacy, because Ginger may ''very well'' be a cat; we just can't ''assume'' so from Tom's argument.

In other words, pointing out somebody's fallacy is not fallacious in itself (you're doing it right), but if a position (such as an already-accepted objective fact) is completely dismissed as false because one of the arguments used to defend it happens to be fallacious, this is the Fallacy Fallacy.

For extra rhetorical effect, this can be combined with StrawmanFallacy when your opponent has both fallacious and valid arguments, by refuting the fallacious arguments and ignoring the valid ones.

Another excellent example of how a [[RightForTheWrongReasons false argument combined with a true conclusion]]: in medicine, pressure around the brain can cause severe headaches. Ancient surgeons assumed that it must be demons in the patient's head causing the pain, and that exposing them to light would kill them or drive them out; therefore, they drilled holes in the patient's skull. The end result relieved the pressure and actually ''did'' cure the headaches, even though their reasoning was entirely faulty.

An argument using fallacious reasoning is capable of being consequentially correct. In logic, "invalid" (fallacious argument) and "false" are ''not synonymous'' (See SoundValidTrue for a more complete explanation of this. There are reasons why extensive Critical Thinking courses exist.) This is related to how [[TropesAreTools logical argument is used as a tool rather than as a fact-in-itself, and that logical validity can sometimes be surpassed by an objective scientific fact]].

See also RightForTheWrongReasons and DumbassHasAPoint.

!!! Examples:
* The use of red lighting to treat smallpox. (By placing dyed cloth over the windows of a room.) This was believed to aid the balance of humours in the body. Now it is assumed to have been effective because the red dye was a natural shield against ultraviolet light.
* Any StrawVulcan character is bound to be written as if "illogical" is a synonym for "wrong."
* A good many theories about the world over the years including many scientific ones are mostly WildMassGuessing for their time that lead to the right conclusions but for the wrong reasons. Freud's theories, for example, are sometimes useful but are based on dated inaccurate knowledge of the mind.
* One of the standard examples of this is Continental Drift: Alfred Wegener was right in that the continents moved, but the process he postulated was dismissed by geologists as being absurd (and they were right). It was the discovery of the mid-ocean ridges and the trenches in the 1950s and 1960s that finally demonstrated the how of plate tectonics.
* Of course, a proposition may fallaciously be declared correct due to an argument against it fallaciously declaring it incorrect due to a particular argument ''for'' it being fallacious, thus committing the ''Fallacy Fallacy Fallacy''.
* One specific FallacyFallacy is based off of the AppealToRidicule. This is very common in political debates, wherein if an individual ridicules some position without backing up the ridicule, the opposing side will assume that the AppealToRidicule was made because the person has no actual argument to make. Instead, the person who made the argument was just trying to be funny, or was just taking some time to enjoy disparaging the opposition. Or the argument was ''so'' transparently ridiculous they didn't think it was worth their time to discredit it (who wants to be the politician caught on camera spending half an hour to explain that they can't disprove the existence of an orbiting teapot?). And of course, even if the person was engaging in a fallacy, it doesn't say anything about others who share their point, and may very well be able to back up their claims.
* Kinda inverting: Martin Gardner, the math popularizer, coined the [[SdrawkcabName Ycallaf]], which is an argument that *looks* like a fallacy but is nevertheless true. (Beloved example: The otherwise fallacious 0=1-1+1-1+...=1-(-1+1-1+)...=1 argument is actually valid when properly interpreted in the [[ItMakesSenseInContext context]] of knot theory.) [[note]]It doesn't prove 0=1 but that -1, i.e. "antiknots" do not exist.[[/note]]
* A beautiful example of the Fallacy Fallacy comes up every time an agency, government, or corporation involved in a controversial issue conducts an internal review or investigation and then publishes results which agree with their desired position. The doubters will immediately resort to an impugning motives form of ad hominem; "Of course that's what they would say! They've got a vested interest!" This may be true, but one cannot logically conclude that the impure motives mean the internal review was falsified. However, in turn, this does not mean there was no cover-up at all. Logic cannot tell us what is true in this case, so we have to switch to other modes of thought to come to a probabilistic conclusion about whether "they" are lying.
-->'''Alice:''' The environmental survey says there will be no damage to caribou populations if we open this area to mining.\\
'''Bob:''' Of course that's what those greedy bastards at Strippit Mining Enterprises would say. They're just publishing research which supports their point of view.\\
'''Alice:''' Hold on; you're just dismissing the report because [[AdHominem the company]] did the research without even examining the report.\\
'''Bob:''' And you're [[AppealToAuthority uncritically accepting their authority]] when they have a clear interest in the conclusion.\\
'''Charlie:''' So basically...you're both talking out of your rear ends.

** Alternate hypothesis analysis shows that an organization coming to a conclusion that suits their vested interest *is* evidence that the conclusion is true--just very weak evidence. Consider: if the mining would harm caribou, what would we expect Strippit Mining to say? That it wouldn't harm caribou,of course. But, suppose the mining would in fact not harm the caribou--what would we expect Strippit to say? Why, that the mining would not harm the caribou. Since one would expect Strippit to say the same thing whether or not it is true, their statement doesn't seem to be evidence one way or the other--and definitely not evidence that their finding is untrue. However, if the mining would harm caribou, there is at least some chance Strippit would admit the harm. Organizations, like people, are sometimes honest even when it is against their best interests. But if the mining would not harm the caribou, it is hard to imagine Strippit lying and saying it would, a lie which would be against their own interests. Therefore, their claim of harmlessness is weak evidence of harmlessness, based on how likely Strippit is to be honest against their own interest. (And Strippit reporting that their mining plan would harm caribou is rather strong evidence that it would. Organizations don't usually lie to harm themselves.)
** Note also that this sort of bias need not involve deliberate lying--people will interpret ambiguous evidence as favoring the conclusion they desire or already believe. That is, we would expect the Ban All Mining And Especially Strippit activist group to report that the mining would harm the caribou whether or not it actually would--and not necessarily through any lying or even lack of diligence on their part.
** And of course if either Strippit or Ban All Mining offers actual proof, this is not disproven by their own self-interest or preexisting ideology.