Answer:
A logical fallacy is a mistaken belief to the effect that inferences having a certain structure are valid. Put another way, a logical fallacy is a belief in the legitimacy of what is in fact an illegitimate rule of inference. As the examples below indicate, logical fallacies are sometimes a reflection of mere prejudice and in other cases they embody actual ratiocinative shortcomings.
Explanation:
Here are some examples:
(1) People will often accept what people in authority, even if the data clearly indicates that they're wrong. If an economist from Harvard weighs in on an issue and homeless person weighs in on that same issue, the economist will be believed and the homeless person will be ridiculed, even if the data makes it very clear that the homeless person is right. (This is known as the 'fallacy of authority.' )
(2) People tend judge others by their words, not their deeds, with the result that a grouchy person who does good is seen as evil, whereas an evil person who pays lip-service to virtue is seen as good.
(3) People assume that what they are not familiar with is impossible. Smith says that his girlfriend has symptoms XYZ and Jones, not having ever personally seen anybody exhibiting those symptoms, refuses on that basis alone to believe Jones.
(4) People have some tendency to assume that entailments are 'convertible', i.e. that if q follows from p, then p also follows from q ('if Smith was decapitated, then he died; so given that he died, he must have been decapitated'). This known as 'affirming the consequent.'
(5) It is assumed that confirmation is transitive, i.e. that if p confirms q and q confirms r, then p confirms. But this is not so. Smith's being a crime boss is evidence of his having considerable, and Smith's having considerable wealth is evidence of his having some kind of legitimate employment; but Smith's being a crime boss is not evidence of his having legitimate employment.
When people commit fallacies 1-3, their doing so tends to have an emotional basis; they want to believe that authority-figures are good people, that people are honest, and that what is strange is impossible. When people commit fallacies 4 and 5, their doing is less a reflection of emotionally rooted prejudices than of sheer lack of acumen. In any case, all of these fallacies are routinely committed.
