I. Petitio Principii: (circular reasoning, circular argument, begging the question) in general, the fallacy of assuming as a premiss a statement which has the same meaning as the conclusion.
–“What a brain! And you know how to prove things, like the big shots?
–Yeah, I have a special method for that. Ask me to prove something for you, something real hard.
–All right, prove to me that giraffes go up in elevators.
–Let’s see. Giraffes go up in elevators … because they go up in elevators.
–Good, that was great! … Suppose I asked you to prove giraffes don’t go up in elevators.
–That’s easy. I just prove the same thing, but the other way around.” Fernando Arrabal, El Cementerio de Automoviles, el Arquitecto y El
III. The reason petitio principii is considered to be a fallacy is not that the inference is invalid (because any statement is indeed equivalent to itself), but that the argument can be deceptive. A statement cannot prove itself. A premiss must have a different source of reason, ground or evidence for its truth from that of the conclusion.
Motte and bailey: Falacy
Motte and bailey (MAB) is a combination of bait-and-switch and equivocation in which someone switches between a “motte” (an easy-to-defend and often common-sense statement, such as “culture shapes our experiences”) and a “bailey” (a hard-to-defend and more controversial statement, such as “cultural knowledge is just as valid as scientific knowledge”) in order to defend a viewpoint. Someone will argue the easy-to-defend position (motte) temporarily, to ward off critics, while the less-defensible position (bailey) remains the desired belief, yet is never actually defended.
In short: instead of defending a weak position (the “bailey”), the arguer retreats to a strong position (the “motte”), while acting as though the positions are equivalent. When the motte has been accepted (or found impenetrable) by an opponent, the arguer continues to believe (and perhaps promote) the bailey.
Note that the MAB works only if the motte and the bailey are sufficiently similar (at least superficially) that one can switch between them while pretending that they are equivalent.
Fox Tweeted A Really Biased Trump-Obama Comparison And They’re Getting Torn To Shreds
Don’t let the recent decision by FOX News to drop anchor Bill O’Reilly amid sexual harassment lawsuits change your opinion of them, they’re still not a very reliable source for news. And yesterday, they gave the perfect example of why they shouldn’t be trusted by tweeting out this comparison of the jobless rates after 100 days in office for the most recent four presidents.
Jobless rate after first 3 months: Trump vs. Obama vs. Bush vs. Clinton. pic.twitter.com/EUTEseJyTj
— Fox News (@FoxNews) April 29, 2017
Soviet Shoe Factory Principle
The factors that are easiest to measure or most visible are the ones that get the most attention, regardless of their importance in comparison to other factors. Another way of saying this is that factors that are easiest to measure or model are not necessarily the most important ones and/or a complete picture, but human nature often forgets this.
In Soviet Russia there is a story of a shoe factory that was pressured to increase production, as measured by quantity of shoes produced. However, the factory was a bit short on materials. So to increase production, the factory decided to produce more children’s shoes, which require less material. Eventually there was a severe shortage of adult shoes, especially larger sizes. However, the factory was meeting its production goals on paper.
We can also imagine that if size quotas were given, there’d be lots of ways to skimp on quality. For example, less threads could be used. If the authorities start counting threads, then old thread can be used. If they find a way to measure the age of the thread (however unlikely), then use cheap leather, cheap glue, cheap paint, etc.
.. I remember one story from a high-school history textbook which was a factory making toy plastic balls had to meet a quota of balls per month, but was never supplied with enough plastic, so it ended up making them thinner and thinner to meet production requirements without any regard for whether they would pop as soon as one kicked them.