Logical failures of inappropriate use of information
Inference from wrong information
Anecdotal evidence - relying on a single case
One of the simplest fallacies is to rely on a private case as proof. For example: quot;There are many proofs that God exists and still performs miracles today. Just last week I read about a girl who was dying of cancer. Her whole family repented, and she was healed” It's perfectly fine to use personal experience to demonstrate a point, but in fact, individual cases prove nothing to anyone. Your friend may claim to have seen Elvis in the supermarket yesterday, but those who haven't will take more than that to be convinced.
Private cases may seem very captivating, especially if the audience wants to believe. This is also part of the explanation for urban legends. Stories that have been verified as false continue to circulate as anecdotes for years.
Audiatur et altera pars – hiding the basic assumptions
Often, people build their argument based on assumptions they don't bother to state. The Audiatur et altera pars principle is that all the basic premises in the argument must be stated explicitly. It is not really a logical fallacy, not to bring all your premises, but a lack of premises combined with an insistence on not providing them, will often be met with suspicion.
Bifurcation – assumption of binaries
Sometimes called the "either-or fallacy", binary assumption occurs when someone presents a situation that has only two explanations, when in fact, there are other explanations that could fit. For example:
"Either man was created as the Bible tells us, or he evolved from inorganic chemicals due to coincidence, as science tells us. What science says is really improbable, so…”
reliance on external authority
Argumentum ad antiquitatem - in the name of antiquity
This is the fallacy of claiming that something is true and good just because it is ancient, or because "things have always been that way". This is the opposite of Argumentum ad Novitatem - in the name of innovation.
"For thousands of years Jews believed in God. Judaism must be right, it has survived for so long, even in the face of persecution"
Argumentum ad lazarum - in the name of modesty
This is the assumption that someone poor knows better, or just more righteous, than someone rich. This is the opposite of an argument in the name of wealth. For example:
"It is more likely that Buddhist monks know the meaning of life, after all they have given up the distractions of material wealth"
Argumentum ad novitatem - in the name of innovation
This is the opposite of an argument in the name of antiquity. This is the fallacy of assuming something is better just because it's newer.
"Explorer 6 is a much better browser than Netscape 5. After all, it came after it"
Argumentum ad numerum - in the name of the crowd
A cousin to the populist argument, this fallacy assumes that the more supporters a claim has, the more likely it is true. For example:
"The majority of the population in Texas believes that the death penalty has great deterrent power. It's really ridiculous to claim otherwise, in light of so much evidence."
"All I'm saying is that thousands of people believe in the power of the pyramids, so there must be something there"
Argumentum ad verecundiam - in the name of reputation
In this fallacy, you are trying to gain support for your argument by using the good reputation of a particular person. For example:
"Isaac Newton was a genius, and he believed in God"
Such a line of argument is not always without value. For example, it may be relevant to seek the opinion of an authority on a certain subject, if this is the subject being discussed. For example, it is easy for us to distinguish between:
"Hawking concluded that black holes emit radiation"
and between
"Peneros concluded that it was impossible to build a thinking computer"
Hawking is a physicist, so it can be expected that his opinion on physical issues is well-founded, while Penrose is a mathematician, and it can be doubted whether he is qualified or not to talk about artificial intelligence.
The Natural Law fallacy - in the name of naturalness
Arguing in the name of nature is a common fallacy in political arguments. One version consists of making an analogy between the conclusion you want to reach and some situation in the natural world, then claiming that reaching the conclusion is inevitable, because the natural world is similar:
"The natural world is a competitive world. Animals are constantly fighting each other to win the limited resources of nature. In the same way, capitalism is basically a competition for capital, and therefore an inseparable part of human nature"
The second form in which this fallacy appears is the claim that because people are products of nature, they must imitate behavior observed in nature, and anyone who does otherwise is 'unnatural':
"Certainly homosexuality is unnatural, when was the last time you saw two animals of the same species mating?"
Argumentum ad crumenam - in the name of wealth
This is the mistake of believing that money is a criterion for correctness. Those with more money are more right than the rest of us. This is the opposite of Argumentum ad Lazarum - in the name of modesty. Example:
"Microsoft's software is necessarily the best. Otherwise how did Bill Gates get so rich?”
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