Voting Theory: Insincere Voting / Strategic Voting


– WELCOME TO A LESSON
ON INSINCERE VOTING. IN THIS LESSON WE’LL DEFINE
INSINCERE VOTING, PROVIDE AN EXAMPLE OF WHEN
INSINCERE VOTING MAY OCCUR, AND FINALLY, INTRODUCE INSTANT
RUNOFF VOTING, WHICH IS MEANT TO ADDRESS
INSINCERE VOTING. IN AN ELECTION,
INSINCERE VOTING, ALSO CALLED TACTICAL VOTING
OR STRATEGIC VOTING, OCCURS WHEN A VOTER SUPPORTS
A CANDIDATE OTHER THAN HIS OR HER SINCERE
PREFERENCE FOR A STRATEGIC PURPOSE, OR TO
PREVENT AN UNDESIRABLE OUTCOME. THIS CAN OCCUR
WHEN MORE THAN ONE CANDIDATE SHARE SOMEWHAT SIMILAR
POINTS OF VIEW. LET’S LOOK AT AN EXAMPLE. HERE ARE THE ELECTION RESULTS
OF A STUDENT BODY PRESIDENTIAL ELECTION, WHERE
CANDIDATE “A” IS A REPUBLICAN, CANDIDATE B IS A DEMOCRATIC, AND CANDIDATE C
IS AN INDEPENDENT. FOR THE PURPOSE
OF AN ILLUSTRATION, LET’S ASSUME THE DEMOCRAT
AND INDEPENDENT SHARE COMMON POINTS OF VIEW
ON SEVERAL ISSUES. BECAUSE CANDIDATES B AND C SHARE
COMMON POINTS OF VIEW, IT IS POSSIBLE THAT SOME
INDEPENDENTS MAY VOTE DEMOCRAT, JUST TO AVOID THE REPUBLICAN
FROM WINNING. SO BY INDEPENDENTS VOTING
DEMOCRAT TO AVOID THE REPUBLICAN FROM WINNING, THIS IS AN EXAMPLE
OF INSINCERE VOTING. NOTICE IN THIS CASE
IF WE USE THE PLURALITY METHOD TO DETERMINE THE WINNER, THE WINNER WOULD
BE THE REPUBLICAN WITH A TOTAL OF 358 FIRST PLACE
VOTES, OR APPROXIMATELY 42.1%
OF THE FIRST PLACE VOTES. NOTICE HOW THIS WIN WOULD
NOT BE A MAJORITY, BUT USING THE PLURALITY METHOD
THE WINNER IS CANDIDATE “A”, THE REPUBLICAN. NOW, BEFORE WE DISCUSS
THE INSTANT RUNOFF METHOD, LET’S DETERMINE THE CONDORCET
WINNER. TO DETERMINE THE CONDORCET WINNER WE DO A ONE-TO-ONE
COMPARISON. SO WE DETERMINE THE WINNER OF
“A” VERSUS B, THEN B VERSUS C, THEN “A”
VERSUS C. SO FOR “A” VERSUS B
WE ELIMINATE C. NOTICE HOW “A” WOULD WIN
IN THE FIRST COLUMN, B WINS HERE AND HERE,
SO “A” VERSUS B IS 358 TO 492, SO B IS PREFERRED OVER “A”. THEN FOR B VERSUS C
WE ELIMINATE “A”. NOTICE B WINS ONLY HERE,
C WINS HERE AND HERE, SO B VERSUS C IS 278 TO 572. C IS PREFERRED OVER B. AND THEN FINALLY FOR “A”
VERSUS C WE ELIMINATE B, SO “A” WINS IN THE FIRST COLUMN,
C WINS HERE AND HERE. SO FOR “A” VERSUS C WE HAVE 358
TO 492. C IS PREFERRED OVER “A”. SO NOTICE C IS PREFERRED
OVER “A” AND B, AND THEREFORE THE CONDORCET
WINNER IS CANDIDATE C, THE INDEPENDENT. BUT NOW LET’S INTRODUCE THE
INSTANT RUNOFF METHOD, WHICH IS MEANT TO ADDRESS
INSINCERE VOTING. INSTANT RUNOFF VOTING, ALSO CALLED PLURALITY
WITH ELIMINATION, IS A MODIFICATION
OF THE PLURALITY METHOD THAT ATTEMPTS TO ADDRESS
THE ISSUE INSINCERE VOTING. AND HERE IS HOW IT WORKS: IN IRV VOTING IS DONE
WITH PREFERENCE BALLOTS, AND A PREFERENCE SCHEDULE
IS GENERATED. THE CHOICE WITH THE LEAST FIRST
PLACE VOTES IS THEN ELIMINATED FROM THE ELECTION, AND ANY VOTES
FOR THAT CANDIDATE ARE REDISTRIBUTED TO THE VOTER’S
NEXT CHOICE. THIS CONTINUES UNTIL A CHOICE
HAS A MAJORITY, OR OVER 50% OF THE VOTES. SO IF A VOTER HAPPENS TO VOTE
FOR A CANDIDATE THAT GETS THE LEAST FIRST PLACE
VOTES, BECAUSE THOSE VOTES
ARE TRANSFERRED TO THEIR NEXT CHOICE, THIS ELIMINATES THE MOTIVATION
FOR INSINCERE VOTING. SO WE GO BACK TO OUR PREVIOUS
EXAMPLE. LET’S DETERMINE THE WINNER
USING THE INSTANT RUNOFF METHOD. NOTICE IN THIS CASE CANDIDATE C HAS THE LEAST FIRST CHOICE
VOTES, AND THEREFORE, USING THE INSTANT
RUNOFF METHOD, WE WOULD ELIMINATE CANDIDATE C. BY DOING THIS, WE WOULD ASSIGN
THESE 214 VOTES TO CANDIDATE B. BUT NOTICE HOW BY USING THIS
METHOD THERE’S NO INCENTIVE FOR THE INDEPENDENTS TO VOTE
FOR THE DEMOCRAT JUST SO THE REPUBLICAN
WOULD LOSE. BECAUSE THEY KNOW IF THEIR
CANDIDATE IS ELIMINATED, THEIR VOTES WILL BE ASSIGNED
TO THEIR SECOND CHOICE. SO IF WE ELIMINATE CANDIDATE C, NOTICE HOW THE REPUBLICANS
STILL HAVE 358 VOTES, BUT NOW THE DEMOCRATS HAVE
214 + 278 VOTES, WHICH GIVES THEM APPROXIMATELY
57.9% OF THE VOTES, AND THEREFORE A MAJORITY. AND THEREFORE CANDIDATE B
IS THE WINNER USING THE INSTANT RUNOFF METHOD. BUT NOTICE AT THE SAME TIME
WE’VE DISCOVERED ONE OF THE ISSUES WITH THE
INSTANT RUNOFF METHOD. IT IS POSSIBLE FOR THE WINNER
OF THE INSTANT RUNOFF METHOD TO VIOLATE THE CONDORCET
CRITERION. BECAUSE REMEMBER THE CONDORCET
WINNER WAS CANDIDATE C, WHO WAS ELIMINATED USING
THE INSTANT RUNOFF METHOD. WE’LL TAKE A LOOK AT THE INSTANT
RUNOFF METHOD IN MORE DETAIL IN THE NEXT LESSON. I HOPE YOU FOUND THIS HELPFUL.  

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Comments

  1. too much examples and semantics and Who'd ever call this "insincere" voting ???? ( inaccurate and negative term) " Strategic  or Tactical is much much better.  Your explaining that instant run off makes tactical voting much more difficult or impossible ? was interesting and helpful

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