The philosopher and mathematician Bertrand Russell suggested the beginning of the 900 puzzle: "In a country there is a barber who shaves all and only those who do not shave themselves. Who shaves the barber?"
solutions are obviously only two: 1. that the barber shave himself 2. that the barber does not shave himself, but in both cases we have a contradiction, that is a contradiction, which makes it impossible both solutions. Let's see why.
1. In the first case, we can formulate the following syllogism:
-The barber only shaves those who do not shave themselves
-the barber shaves himself then
-the barber does not shave himself
(the contradiction is that, if The barber shaves himself, then does not shave himself, then it is impossible bay itself, because this would lead to a solution contradictory).
2.In the second case, we can formulate the following syllogism:
-The barber only shaves those who do not shave themselves
-the barber does not shave himself then
-the barber shaves himself
(the contradiction lies in the fact that if the barber does not shave himself, then shaves himself, then is impossible not to shave himself , because even this solution would lead to a contradiction).
Therefore, the barber can not shave, but at the same time, can not not to shave.
Since this is a contradiction in turn, makes it impossible for the initial condition, namely that there is a barber who shaves all those who do not shave, since this condition would lead to an absurdity.
So can not be true that in a country there is a barber who shaves only those who do not shave themselves, and Lord Russell has made a fool of us.
(PS ancient antinomies are often used to demonstrate that the reality or does not exist or is only an illusion)
0 comments:
Post a Comment