Wednesday, April 19, 2006

There is no such thing as common sense

"Common sense is the collection of prejudices acquired by age eighteen."
  "The man who has no tincture of philosophy goes through life imprisoned in the prejudices derived from common sense, from the habitual beliefs of his age or his nation, and from convictions which have grown up in his mind without the co-operation or consent of his deliberate reason."
-Bertrand Russell
"unencumbered by the thought process"
- motto of radio show Car Talk

This is a rant page, creating a location I can point to, expounding my claim that there is no such thing as common sense, and if you think that there is then you haven't gotten out into the world enough.  The only reason common sense seems common is that you've only dealt with people very much like you. There are other web pages that take a similar stance.
"To determine the value of philosophy, we must first free our minds from the prejudices of what are wrongly called 'practical' men."
-Bertrand Russell

A secondary belief of mine is that, real or not, so-called common sense should not be the answer to the question "Why?" or "How?".  It is an answer that is a get-out-of-jail-free card for non-thinkers.  It allows them to make decisions Unencumbered By The Thought Process. I've always thought this (and it doesn't matter that I might have Asperger's... LOL), but I was bolstered in my belief when I found out that most Philosophers think so little of it that they have a name for it (which isn't a compliment): Naive Realism.

See/Hear the "Making Decisions" show of Philosophy Talk where the guest talks about the documented value of skeptics & contrarians in group settings, not because they are right or wrong, but because they free up people to go against group think who otherwise wouldn't speak up. Better for decisions even if more of a pain in the butt for those going thru the process.

Episode 12 (Probability and Modern Science) of the TTC Video Series Mathematics, Philosophy, and the 'Real World' gives a couple of examples of naive intuition as a bad thing…

- A study from 1980 is mentioned where a number of medical Drs were asked to translate the word "likely" (as in "likely to have a disease") into a percentage (as in "percent chance of having the disease"). Amazingly, the answers ranged from 20% to 95%

- An example is given of people's intuition about statistics being very wrong where a jury thinks there is a good chance that a witness is correct when he says he saw a blue car at night.  FACTS: (1) witness was tested as being 80% correct when reporting car color at night, AND, (2) there are 15% blue cars and 85% green cars in population. In fact the probability that he was wrong is over half!
Because of so many green cars in total population, the witness will wrongly identify more green cars as blue (17% of total population) [i.e. 20% wrong of 85% green; 85x.2=17] than correctly identify blue cars as blue (12% of total population) [i.e. 80% right of 15% blue; 15x.8=12].

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