The paradox of democracy: Arrow impossibility explained

The paradox of democracy: Arrow impossibility explained

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Language: English

Type: Robot

Number of phrases: 61

Number of words: 410

Number of symbols: 1911

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00:03
democracy as in one-man one-vote it's regarded as being the type of government to aspire to however it has its problems the public do not necessarily possess any particular collective wisdom and there's a danger of trial by plebiscite over topical or emotive issues if policy is based on popular opinion that people are asked on the street what sort of environmental problem they consider most important they are more likely to answer litter rather than global warming because the problem of litter is
00:35
immediate and in front of them whereas climate change is something perceived as being out of their control and external that the main problem is that a democratic approach decision-making can create logically inconsistent results as we're going to demonstrate here today this inherent difficulty with democracy was elegantly demonstrated using set theory by the Nobel prize-winning economist Ken arrow and is now known as arrow impossibility in its simplest form
01:07
it can be represented by three people let's call them James Simon and Mary who each rank three preferences a B and C in an order one two or three each person ranks their preferences in a different order this simulates the wide difference of opinion that might be found amongst the general public the trick is to look at the ranking order of the preferences chosen by each person don't add up the numbers it's the ranking that we need to
01:38
compare how many people prefer option a to option B by looking at the table you can see that two people have this ranking two out of three people means that a majority have this preference then have a look and see how many people prefer option B to option C as before - people prefer this ranking so again a majority so it logically follows that the majority of our community of three people prefer option
02:12
a to option C as the majority prefer both a to B and B to C however here comes the paradox if you look at the number of people who rank their preference for option C above option A than it is again a majority so we have the majority preferring both a to C and C to a which is of course quite impossible if you want to know more about the types of principles that can be applied to dealing with the problems
02:43
of aggregating social preferences join us on the environmental challenges program

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