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Logical Nonsense (Posted on 2003-08-26) Difficulty: 4 of 5
  • All, who neither dance on tight ropes nor eat peanut butter, are tall.

  • Creatures with spikey hair who look silly will go swimming if they do not dance on tight-ropes.

  • A kangaroo looks silly wearing sunglasses.

  • A smart creature will always do what he ought to do.

  • No one ought to go swimming who looks silly and eats peanut butter.

  • A smart driver wears sunglasses.

  • Kangaroos that have sneezing fits are avoided.

  • Short creatures who go driving have sneezing fits.

  • No creatures ought to dance on tight-ropes if they have sneezing fits.

  • All, who do not dance on tight-ropes and who are avoided, have spikey hair.
Therefore, no short kangaroos who are smart...

See The Solution Submitted by DJ    
Rating: 4.2105 (19 votes)

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my tentative solution | Comment 3 of 13 |
No short kangaroos who are smart should drive a car. If they do, they will be caught in a confusion of rules:
If they drive, they will, being smart, wear sunglasses and look silly. Being short, they will sneeze and therefore be avoided. As sneezers they won't dance on tightropes. But it forces them to eat peanut butter (as all non-tightope dancers who dont eat it are tall). Being avoided, non-tightrope dancers would mean they had spikey hair. As spikey haired, silly looking non-tightrope dancers, they 'may' swim, but as peanut butter eating, silly looking creatures they should not.
(In the 4th statement:'no one ought' doesnt say one could NOT swim, but since our kangas are smart, we'll assume they would do what is best. Similarly, statement 2's 'may' isnt a 'must' so they are not compelled to swim, but then rule 4 would seem to make rule 2 at best imcomplete, possibly false)
All the kangas have to do to avoid this confusion is not drive. They need not look silly or be avoided. They are free to swim, dance tightropes and eat or not eat peanut butter so long as they dont try to avoid both tightrope dancing and peanut butter eating (or they wouldnt be short). If the kangaroos can deal with the social ostracism i.e.looking silly and being avoided (a moot point whether smart kangas would choose this) they might prefer the former scenario and drive or not drive and just decide not to swim.
What do you think?
  Posted by catherine on 2003-08-26 23:26:31
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