Essential Questions

This is a dynamic list of possible statements about what single-winner election methods should be like. It is meant to give a survey of the EM list members' basic opinions.

Each list member can add their own column and express their degree of agreement below each of the statements. For reasons of space, please just put your initials in the column's head.

When you add a new statement about some essential property of election methods, please try to formulate it as clear as possible, using as few ambiguous terms as possible, and keep the list sorted by groups of related statements.

Please do not change the wording of statements as soon as someone expressed a degree of agreement. If you do, please announce on EM list, add a new line of degrees of agreement and put the old line of degrees of agreement in brackets.

Degrees of agreement

++  I agree strongly
 +  I rather agree
 0  I am indifferent about this
 -  I rather disagree
--  I disagree strongly

 ?  I am undecided about this

Statements and agreement by category

STATEMENT
  DEGREE OF AGREEMENT BY... (INITIALS)

• What are the goals of single-winner election methods?

  SR  JH  JG  KV MO
to elect a winner
  ++  ++  ++  ++ ++
to provide a social order (=ranking)
  ++  --  0   0   0
to make people vote "honestly"
  ++   +  ?   ++  0

to allow people to vote honestly
                  ++
to gain detailed information about voters' preferences
   +   +  +   +  ++
to give voters with no information about others' preferences equal power
  ++   +  +   +   +
to give both majorities and minorities a fair amount of power
  ++  ++  -   ?   -

• What information should be asked for and used?

  SR  JH  JG  KV
Pairwise preference information (e.g. rankings) should be used
  ++   +  ++   +  ++
Approval information (e.g. cutoffs) should be used
   +  ++   ?   -  +
Cardinal ratings information should be used
   -   -   +  --  +
Strategic information (e.g. AERLO) should be used
  --  --   ?  --   ++
It should be possible to rank X and Y equal independently of whether they are approved
   +  ++   +   ?    +
It should be possible to rank X over Y without the need to either rank Z over Y or X over Z
   +  ++   ?  --    ?
It should be possible to rank X over Y and Y over Z without the need to rank X over Z
   --  +  --  --    -

• How should this information be interpreted?

  SR  JH  JG  KV MO
Approval information should be interpreted as cardinal rates of, say, 0 or 1
   +   -   +   +  +
Ranking X and Y equal means X and Y should get the same probability of winning
  ++   +   ?   ? -
Ranking X and Y equal means the decision about X and Y should be delegated to the other voters
   -   -   -   -  +
Expressing undecidedness between X and Y means this decision should be delegated to the others
  ++  ++   -   -  +

• What about certain types of "winners" and "losers"?

  SR  JH  JG  KV MO
Beats-All Winners (=Condorcet Winners) must win with certainty
  ++   -  ++   0  --
Beats-All Winners must not lose with certainty
  ++  ++  ++   0  ?
Approval Winners must not lose with certainty
   -   +  --  --  ?
Beaten-By-All Losers (=Condorcet Losers) must not win
  ++   ?  ++   + --
A Beaten-By-All Loser must not win unless s/he is an Approval Winner
  --  ++   -   0
Beaten-By-All Losers must have winning probability less than 1/2
   +   +   +   + 0
Approval Losers must not win
   -   -  --  -- 0
An Approval Loser must not win unless s/he is a Condorcet Winner
   +   +  --  -- 0

• What other special properties should the winner have?

  SR  JH  JG  KV
The winner must belong to the Smith/GeTChA/Top Set
  ++   -  ++   -
The winner must be top on at least one ballot
  --   ?   0   0

• What effects should certain manipulations have?

  SR  JH  JG  KV
Raising X on one ballot without changing anything else must not decrease X's winning probability
  ++  ++   +  ++
Adding a ballot which only ranks X must not decrease X's winning probability
  ++  ++   ?   +
Adding a ballot saying "X>(whatever)" must not decrease X's winning probability
  ++   ?   ?   +
Changing a ballot which only ranks X to "X>(whatever)" must not decrease X's winning probability
  --   -   ?   +
Changing a detail "X>Y" to "Y>X" on one ballot should be unlikely to change the winner from W to Z
  ++   +   ?   0
Cloning must not affect the other candidates' winning probabilities
  ++  ++   +   +
Nominating "noise" candidates which are not liked much should be unlikely to change the outcome
  ++   +   +  ++

• Questions of trade-off

   SR  JH  JG  KV
 Freedom of preference expression is more important than anti-strategic properties
    -   +   ?   ?
 Efficiency is more important than simplicity
    ++  ?   +   ?