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Fast above

Posers and Puzzles

21 Jul 11

Thequ1ck

Fast above

Slow Below

Joined: 29 Sep 03
Moves: 25914

21 Jul 11

Suppose there is a town with just one male barber; and that every man in the town keeps himself clean-shaven: some by shaving themselves, some by attending the barber. It seems reasonable to imagine that the barber obeys the following rule: He shaves all and only those men in town who do not shave themselves.

Under this scenario, we can ask the following question: Does the barber shave himself?

Shallow Blue

Joined: 18 Jan 07
Moves: 12466

21 Jul 11

Originally posted by Thequ1ck
Suppose there is a town with just one male barber; and that every man in the town keeps himself clean-shaven: some by shaving themselves, some by attending the barber. It seems reasonable to imagine that the barber obeys the following rule: He shaves all and only those men in town who do not shave themselves.

Under this scenario, we can ask the following question: Does the barber shave himself?

You are Bertrand Russell, and I claim my £5,—.

Richard

forkedknight

Defend the Universe

127.0.0.1

Joined: 18 Dec 03
Moves: 16687

21 Jul 11

Yes, at home in front of the mirror 🙂

TomCr

woodpusher

Cincinnati

Joined: 13 Jun 10
Moves: 23143

21 Jul 11

he goes to the implied female barber

AThousandYoung

Insanity at Masada

tinyurl.com/mw7txe34

Joined: 23 Aug 04
Moves: 26660

21 Jul 11

Originally posted by Thequ1ck
Suppose there is a town with just one male barber; and that every man in the town keeps himself clean-shaven: some by shaving themselves, some by attending the barber. It seems reasonable to imagine that the barber obeys the following rule: He shaves all and only those men in town who do not shave themselves.

Under this scenario, we can ask the following question: Does the barber shave himself?

Obviously the "reasonable" rule is unreasonable. Of course he does.

Palynka

Upward Spiral

Halfway

Joined: 02 Aug 04
Moves: 8702

21 Jul 11

2 edits

Originally posted by TomCr
he goes to the implied female barber

Well spotted, although she might go bankrupt with only one client.

Edit - Nah, still doesn't work.

iamatiger

Joined: 26 Apr 03
Moves: 26771

22 Jul 11

The front door of the barber's shop is in town. The back room where he sits is not, and he shaves himself.

Banana King

Joined: 24 Jan 09
Moves: 5514

22 Jul 11

sometimes

Banana King

Joined: 24 Jan 09
Moves: 5514

22 Jul 11

the barber shaves himself when he's not shaving himself, and he doesnt shave himself when he is! lol

LemonJello

Joined: 24 Apr 05
Moves: 3061

22 Jul 11

Originally posted by Thequ1ck
Suppose there is a town with just one male barber; and that every man in the town keeps himself clean-shaven: some by shaving themselves, some by attending the barber. It seems reasonable to imagine that the barber obeys the following rule: He shaves all and only those men in town who do not shave themselves.

Under this scenario, we can ask the following question: Does the barber shave himself?

ATY already gave the right response. Given your supposition, the barber shaves himself and it is wrong to say that it is reasonable to describe this barber by the rule you provide.

What you present is not a paradox. The "rule" you provide, though, would be where a paradox lies.