27 Nov 2020

Bob Murphy Show ep. 166: Arrow’s Impossibility Theorem

Bob Murphy Show 7 Comments

Spelled out for you…

7 Responses to “Bob Murphy Show ep. 166: Arrow’s Impossibility Theorem”

  1. J.D. Wells says:

    As your sitting there you have to weigh the consequences, but you also may have to show some form of force to ensure you keep the upper edge.

    You simply get out your cell phone & call 911.

    When they answer you say;

    “Yes, can you please send an ambulance to the dinner you are in… & also request a law enforcement presence to witness the pending assault that will occur if they don’t get there in time…”.

    Either way it ends you have a backup plan… medical help for yourself or the other person & or Law Enforcement help to even the odds . Is it justified? Hell yes, given the recent current events and the potential outcome.

    Also, you have more options either way you want to drive it from that point. If you want to push the individual to use unlawful force against you, so you can “defend” yourself, you can. If you want to avoid the fight, you can by getting more help there to solve the situation that way. Either way you are the driving force to end the situation.

    • Bob Murphy says:

      Can you post this in the other thread? But just to warn you, calling the police would be threatening the use of violence to solve the problem, and so that isn’t a legal answer if you intended this as a submission.

      • J.D. Wells says:

        But your really not “threatening” anything. Your just using you cell phone to notify someone else about the pending situation. There’s no threat, only what the other person may perceive as a threat.

        • random person says:

          Using that logic, would it also not count as violence if someone, say, phoned up a Mafia boss who owed him a favor, or a KGB officer?

  2. Capt. J Parker says:

    Thanks for the Arrow Impossibility Theorem discussion. Very topical for me. The question of whether to adopt ranked choice voting was on the ballot here in Massachusetts last month. Prior to the election I was discussing the issue with a neighbor who happens to be a Political Science professor. His take was the ranked-choice was the best way to achieve an election outcome that best satisfies the desires of the electorate (or words to that effect – it was a casual discussion.) I responded that I wasn’t so sure and that I thought Ken Arrow had shown that here wasn’t any such thing as a method that “best satisfies the desires of the electorate.”

    My neighbor replied “Oh yeah – Arrow – I recall something about that” But neither of us could recall enough detail to about the Impossibility Theorem to have an informed discussion of ranked-choice so we resolved to research and discuss at a later date. The ballot measure BTW did not pass.

    One thing I did turn up is that Arrow himself did not believe his theorem implied all voting schemes were equally bad. For one example see: https://electionscience.org/commentary-analysis/voting-theory-remembering-kenneth-arrow-and-his-impossibility-theorem/

    I’ll end with two questions in case anyone who follows Dr. Murphy cares to answer them:
    1) Does anyone know of a mathematical public choice study of ranked-choice vs plurality voting schemes?
    2) My scan of the internet says that Republicans and conservatives prefer plurality voting or runoffs over ranked choice while Democrats and progressives prefer ranked choice. Why would this be?

  3. Harold says:

    Gibbard’s Theorem may be a strating point. I don’t really get it after a quick read through.

    One key outcome seems to be that if you restrict the possible outcomes to two only, you can avoid dictator and tactical voting.

    • Capt. J Parker says:

      Thanks Harold. Checking it out now.

Leave a Reply