[lit-ideas] Re: Try a Logic Problem

  • From: Robert Paul <rpaul@xxxxxxxx>
  • To: lit-ideas@xxxxxxxxxxxxx
  • Date: Thu, 22 Jun 2006 14:27:56 -0700

Paul Stone wrote:

The blind guy has a white hat on.

1) Prisoner 1 can see both 2 and 3's hats. He doesn't know what his hat is, therefore, their hats have to be white and red or two whites.

2) Prisoner 2 can see both 1 and 3's hats. He doesn't know what his hat is, therefore 1 and 3 must be wearing either W/W or R/W.

3) Since neither prisoner 1 or 2 knows which colour hat they have on, they must BOTH be wearing red ones because, if 3 had a red hat on, prisoner #2 would KNOW that he has a white one on -- since both 2 and 3 can't both have Reds or number 1 would know that he has a white one on.

This problem appeared in I. M. Copi's Introduction to Logic (whichever edition was current in the mid-1960s). I was teaching at the University of Oregon then and for pocket money I taught correspondence courses in the three philosophy intro courses: logic, ethics, and 'problems.' Almost all of my students were prisoners in the state penitentiary in Salem. Copi's book was rife with derogatory references to prisoners, on the level of 'All prisoners are morons' (not an actual example), and I made an effort at political correctness avant la lettre by trying to get the State to recommend a different text. I moved on to Reed before anything came of that.

I think I still have a 'dittoed'* step-by-step solution to this problem somewhere. If I find it I'll send it to the Philosophy Museum at Memorial University.

*See http://www.deadmedia.org/notes/40/408.html

Robert Paul
Reed College
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