Fallacist's Fallacy
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[edit] Definition
The so-called Fallacists Fallacy, also known by the Latin name argumentum ad logicam ("argument [aimed] at logic"), is an informal logical fallacy where a participant invalidly rejects a proposition because the arguments made in favor of the proposition are themselves fallacious The most general structure of this argument runs something like the following:
- P because of <fallacious argument>
- Therefore, not-P.
This is a fallacy because the fact that a bad argument can be presented in support of a proposition does not necessarily mean that there are no other good arguments available.
[edit] Example
Example 1:
- Protagonist: Einstein said, "God does not play dice with the universe." If a scientist like Einstein believed in God, obviously God must exist.
- Antagonist: That's an appeal to authority fallacy, so God doesn't exist.
Example 2:
- Protagonist: Everything that flies is a bird or a bat. Since eagles fly, and they're obviously not bats, they must be birds.
- Antagonist: That's the fallacy of false dichotomy, so we clearly don't know whether eagles are birds or not.
In either case, although Protagonist's argument itself is fallacious, the conclusion might be true. For the second example in particular, the truth of the conclusion can be easily demonstrated through other arguments (Eagles have feathers, only birds have feathers, therefore eagles are birds).
[edit] Discussion
In formal logic, an argument is considered to be sound if, whenever the premises are true, the conclusion must also be true. For example, the Barbara syllogism is an example of a sound argument:
- All As are Bs
- All Bs are Cs
- Therefore, all As are Cs
Under any possible interpretation A, B, and C, if the first two statements are true, the third must equally be true. A 'fallacy is formally defined as an unsound argument, an argument where even if the premises are true, the conclusion might not be true. An example of this would be the following (unsound) syllogism:
- All frogs are vertebrates
- Some vertebrates live in trees
- Therefore, some frogs live in trees.
As it happens, the conclusion of this argument is true, as are the premises. But an argument of similar form -- replace "frogs" with "trout" in the above argument -- would have true premises but a false conclusion. Therefore, the argument above is fallacious, even when the conclusion ("some frogs live in trees") happens to be true.
Therefore, just because an argument can be shown to be similar in construction to a known fallacy does not make its conclusion wrong. The most that can be said about a proposition supported by a fallacious argument is that the argument does not necessarily support the proposition. There may be other sources of evidence that can be drawn upon (we still know that eagles are birds), and the evidence of the argument itself may still need to be taken into account.
In real life, it is rather rare that people have the luxury of being able to make statements that are provably true or false. Most arguments put forth are therefore formally fallacious, even if they are rational and convincing. For example, just because a respected group of doctors makes a statement supporting a particular medical treatment does not mean that the treatment is necessarily safe or effective. Panels of doctors have been wrong before. For this reason, "appeal to authority" is regarded as a fallacy; the judgement of experts is not necessarily a guarantee of truth. On the other hand, in matters within their area of expertise, the judgement of experts is usually likely to be much more accurate and reliable than the judgements of non-experts, which is why the experts are experts in the first place.
It is therefore sometimes necessary to distinguish between formally fallacious but nevertheless "rational" arguments, such as an appeal to the judgement of doctors on medical matters, or an ad hominem argument that attacks the credibility of the witness, and fallacious arguments where a close reading shows that the argument provides little convincing evidence. Examples of this might include an appeal to the authority of doctors on a matter of law or theology (matters in which they have no particular authority) or an irrelevant ad hominem argument.
[edit] Exceptions to the Rule
Any time an argument is suspected of being fallacious, it is necessary to consider the question of whether the argument is still "rational" in the sense defined above. If the argument still provides what a rational observer considers to be support for the proposition, even if the support isn't 100% watertight, the proposition may still be true.
