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Questions tagged [paradox]

A puzzle in which a seemingly impossible situation is presented, or any sort of construction that results in a logical contradiction.

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25
votes
8answers
8k views

Unexpected hanging paradox

The unexpected hanging paradox is as follows: A judge tells a condemned prisoner that he will be hanged at noon on one weekday in the following week but that the execution will be a surprise to ...
14
votes
10answers
3k views

How can the “Boy or Girl” paradox be worded unambiguously?

The first time I encountered the Boy or Girl paradox I was struck by how ambiguous all of the formulations in English are. As Wikipedia notes: Gardner argued that a "failure to specify the ...
3
votes
3answers
850 views

A boy and his father [closed]

A young boy is taking a ride with his dad when a truck runs them off the road, killing the father and critically injuring the young boy. He's Medivac'd to the nearest hospital as the child is lying on ...
1
vote
5answers
949 views

Obi-Wan vs Grievous

19 BBY, the Galactic Republic spots General Grievous in Utapau, the Separatists' Council Base; the Jedi Obi-Wan Kenobi is sent there to deal with him. After a long search, Obi-Wan comes face to face ...
44
votes
7answers
9k views

How many tries to roll a 6?

Suppose you roll a (fair, 6-sided, perfectly ordinary) die repeatedly until you roll a 6. As is well known, the expected (i.e., long-term average over many trials) number of rolls required is 6. Now ...
15
votes
10answers
2k views

Two many rainbows?

Wish I’d had a camera at the time but a cartoon will have to suffice, representing two actual incomplete rainbows that stop in midair where they meet, lit only by a setting sun. This seemed so ...
9
votes
2answers
597 views

Epimenides paradox

Epimenides (a Cretan) once wrote a poem, in which he stated that all Cretans are liars. Since he is a Cretan, and therefore a liar, Cretans are veracious. But then again he wouldn't be a liar! This ...
9
votes
3answers
951 views

Who's the oldest?

A child is born on August 19th 2016 00:12 (local time) on timezone GMT + 1. Another child is born on August 18th 2016 23:48 (local time) on timezone GMT. Which one is the oldest? Note: Not sure I ...