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Re: Erroneous conclusions from applying material conditionals?

Newsgroups sci.logic
Date 2023-05-29 09:56 -0700
References (3 earlier) <d6f79405-3d99-4a01-b273-9fd27714f9e1n@googlegroups.com> <329534ce-a2f3-4c92-99a5-1002523de16dn@googlegroups.com> <bd760a62-c8e4-4551-ac78-ac349b9971c6n@googlegroups.com> <f5cbc146-4b54-47a8-ac06-751128790439n@googlegroups.com> <96a1f35a-d729-4792-a22a-46d65dabefban@googlegroups.com>
Message-ID <c7e9f27e-7f7a-4370-b135-e3c798029115n@googlegroups.com> (permalink)
Subject Re: Erroneous conclusions from applying material conditionals?
From Dan Christensen <Dan_Christensen@sympatico.ca>

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On Monday, May 29, 2023 at 11:30:33 AM UTC-4, Mild Shock wrote:
> Already using this alone, where U represents the guests of the pub:
> EXIST(x):[x e U & (x e s => Q(x,s))]
> Prevents your errorneous conclusion. After all, Smullyan 
> talks about a man at the bar, the place inside a pub 
> where you usually order a drink. Not on venus or mars: 
> 
> "A man was at a bar. He suddenly slammed down his 
> fist and said, " Gimme a drink, and give everyone elsch 
> a drink, caush when I drink, everybody drinksh!" So drinks 
> were happily passed around the house." 

Smullyan's informal proof:

"Either it is true that everybody drinks or it isn't. Suppose it is true that everybody drinks. Then take any person--call him Jim. Since everybody drinks and Jim drinks, then it is true that if Jim drinks then everybody drinks. So, there is at least one person namely Jim-such that if he drinks then everybody drinks. 

"Suppose, however, that it is not true that everybody drinks; what then? Well, in that case there is at least one person-call him Jim-who doesn't drink. Since it is false that Jim drinks, then it is true that if Jim drinks, everybody drinks. So again there is a person--namely Jim--such that if he drinks, everybody drinks."

--"What is the name of this book?" pp. 209-210

Hmmm.... No mention of any pub or and other location. In your "standard" FOL, Smullyan's Drinkers' Principle would be Ex(Dx => AyD(y)). Nothing corresponding to anything like a pub. What gives? 

> https://cs.bme.hu/~szeredi/ait/Smullyan-What-is-the-Name-of-This-Book.pdf 
> 

For a set-theoretic variation of DP that includes explicit mention of a pub set p (unlike Smullyan's original version), see the thread, "Yet another set-theoretic variation of the Drinkers' Paradox." There, using ordinary set theory and basic logic, I prove:

ALL(d):ALL(p):[Set(d) & Set(p) => EXIST(x):[x in d => p=d]]

Where d could be thought of as the set of people drinking in given pub, and p as the set of all people in that pub. Note that d and p are arbitrary, possibly empty sets. Since these are arbitrary sets, this results holds whether or not d is a subset of p.

Dan

Download my DC Proof 2.0 freeware at http://www.dcproof.com
Visit my Math Blog at http://www.dcproof.wordpress.com

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Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-27 12:04 -0700
  Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-27 13:25 -0700
    Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-27 19:42 -0700
  Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 08:39 -0700
    Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 11:50 -0700
    Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 12:01 -0700
      Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 13:47 -0700
        Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 13:57 -0700
          Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 14:02 -0700
          Re: Erroneous conclusions from applying material conditionals? olcott <polcott2@gmail.com> - 2023-05-28 16:12 -0500
          Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 15:39 -0700
            Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 15:56 -0700
              Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 16:04 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 16:14 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 16:24 -0700
              Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 16:49 -0700
              Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 16:52 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <janburse@fastmail.fm> - 2023-05-29 02:25 +0200
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <janburse@fastmail.fm> - 2023-05-29 02:31 +0200
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <janburse@fastmail.fm> - 2023-05-29 02:45 +0200
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 17:59 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 17:46 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 17:51 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 18:01 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 18:07 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 18:12 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 18:15 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 18:17 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 18:23 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-28 18:28 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 18:46 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-28 21:51 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-28 22:14 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 22:33 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 22:36 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-29 09:01 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 09:27 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 09:32 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 09:35 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 10:03 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <janburse@fastmail.fm> - 2023-05-29 19:45 +0200
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-30 05:52 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-30 15:16 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-29 11:14 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-29 22:53 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-30 17:45 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 08:23 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-31 13:22 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-31 13:31 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-31 13:38 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-31 13:51 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-01 19:56 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-01 21:35 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 21:44 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 18:54 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-01 19:55 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 21:13 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 21:19 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 21:23 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 21:30 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-01 22:02 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 22:28 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 22:31 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 22:34 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 22:39 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 23:29 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-03 14:14 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-03 14:23 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 23:26 -0700
                Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-02 09:42 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 20:41 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 20:58 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 21:24 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 21:28 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 21:31 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-01 21:34 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 22:49 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-03 04:49 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-03 04:51 -0700
        Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-28 15:33 -0700
    Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 02:52 -0700
      Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 02:58 -0700
        Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 03:03 -0700
          Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 07:35 -0700
            Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 08:23 -0700
              Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 08:30 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 08:33 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 09:56 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <janburse@fastmail.fm> - 2023-05-29 19:56 +0200
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 11:40 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 11:43 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 13:32 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 13:38 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 13:59 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 15:19 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 15:21 -0700
                Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-05-29 17:37 -0700
                Re: Erroneous conclusions from applying material conditionals? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-29 19:00 -0700
  Re: Erroneous conclusions from applying material conditionals? Mild Shock <janburse@fastmail.fm> - 2023-06-02 09:41 +0200
    Re: Erroneous conclusions from applying material conditionals? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-02 09:42 -0700
      Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-02 11:00 -0700
        Re: Erroneous conclusions from applying material conditionals? Mild Shock <bursejan@gmail.com> - 2023-06-02 11:14 -0700

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