The Wason Card Problem
is a well known test in the study of deductive reasoning.
You are given 4 cards, two face up and two face down; say, 3,8, Red, Brown, and asked which card(s) must be turned over in order to test the truth of the proposition that if a card shows an even number on one face, then its opposite face is Red?
Apparently only a small percentage of those tested give the 'correct' solution - although the 'great majority of subjects agree with the logic of the solution, once it is explained to them'.
The 'correct' solution is given in the article, but it is worth attempting to solve it first, if you are not already familiar with it.
Question: Why is the 'correct' solution in fact questionable?
(In reply to solution
broll's problem, as written, leaves open the possibility that the '3' has an even number on the other side. However the Wikipedia link he posted does not (italics added)
You are shown a set of four cards placed on a table, each of which has a number on one side and a colored patch on the other side. The visible faces of the cards show 3, 8, red and brown. Which card(s) must you turn over in order to test the truth of the proposition that if a card shows an even number on one face, then its opposite face is red?
So if one does not read broll's first paragraph carefully you may not notice the missing clause.
It makes for a nice puzzle and it fooled me.
The 'correct' solution given on Wikipedia is indeed correct.
Posted by Jer
on 2015-06-01 13:48:35