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THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢欢 Peter Emerson The de Borda Institute 欢欢欢欢欢欢

THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

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Page 1: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY

AND ITS WORLD-WIDE CONSEQUENCES

欢迎

Peter Emerson

The de Borda Institute

德博达研究所

Page 2: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

ZIMBABWE

President Mugabe:

Elections: first-past-the-post

Governance: majority vote

Page 3: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

EGYPT

Constitutional Referendum

Yes 77.3%

No 22.7%

(41% turnout)

Page 4: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

MAJORITARIANISM(majority rule by majority vote)

The (simple or weighted) majority vote is the most inaccurate measure of collective opinion ever invented.

Page 5: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

CLOSED

QUESTIONS

SEMI-OPEN

QUESTIONS

OPEN

QUESTIONS

↑All

prefs

Borda

BC / MBC

non

Major-

C AV = alternative vote

BC = Borda Count

IRV = instant run-off

MBC = modified Borda count

STV = single transferable vote

Condorcet

(Copeland)

M

A

J

O

R

I

T

A

R

I

A

N

OSome

Approval

voting

U prefs Serial voting

Sweden*

AV = IRV = STV

N 1st

prefs

only

Weighted majority

SA, UN

Consociational

NI, Belgium

2-round voting

Norway**

T Simple majority

Ireland, UK

Twin Majority

Switzerland

Plurality

New Zealand

* a series of majority votes

** a first-round plurality and then a majority vote

1 of 2

options

1 of some options

1 or some of some options

1or some or all of all options

1st preference only Preferential

BINARY MULTI-OPTIONAL

VOTERS’ CHOICE → →

DECISION-MAKING

Page 6: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

‘DEMOCRATIC’ (?) DICTATORS

Page 7: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

OPTIONSVoters and their preferences

i j k l m n p

A 1 1 1 4 4 4 4B 2 3 3 1 2 3 3C 3 2 2 2 1 2 2D 4 4 4 3 3 1 1

A VOTERS’ PROFILE

Page 8: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

OPTIONSVoters and their preferences

i j k l m n p

A 1 1 1 4 4 4 4B 2 3 3 1 2 3 3C 3 2 2 2 1 2 2D 4 4 4 3 3 1 1

A VOTERS’ PROFILE

Page 9: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

OPTIONSVoters and their preferences

i j k l m n p

A 1 1 1 4 4 4 4B 2 3 3 1 2 3 3C 3 2 2 2 1 2 2D 4 4 4 3 3 1 1

A VOTERS’ PROFILE

Page 10: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

OPTIONSVoters and their preferences

MBCCon-dor-cet

i j k l m n p

A 1 1 1 4 4 4 4 16 0B 2 3 3 1 2 3 3 18 2C 3 2 2 2 1 2 2 21 3D 4 4 4 3 3 1 1 15 1

A VOTERS’ PROFILE

Page 11: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

MethodologySocial Choice

and Social Ranking

Examples of use in:

1st 2nd 3rd 4th Decision-making Elections

Plurality vote A D B/C

UK (where it is called FPP)

KenyaTwo-round system

D A - - New Zealand (referendums)

Norway (in parliament)

FranceCôte d'Ivoire

AV B A - - AustraliaBC/MBC C B A D SloveniaCondorcet C B D A -

‘DEMOCRATIC’ RESULTS

Page 12: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

PARTIAL VOTING IN AN MBC

He who votes for 1 option gives his favourite 1 pt.

Page 13: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

PARTIAL VOTING IN AN MBC

He who votes for 1 option gives his favourite 1 pt.

She who votes for 2 options gives her favourite 2 pts (and her 2nd choice 1 pt).

Page 14: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

PARTIAL VOTING IN AN MBC

He who votes for 1 option gives his favourite 1 pt.

She who votes for 2 options gives her favourite 2 pts (and her 2nd choice 1 pt).

He who votes for 3 options gives his favourite 3 pts, (his 2nd choice 2 pts and his 3rd choice 1 pt).

Page 15: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

PARTIAL VOTING IN AN MBC

He who votes for 1 option gives his favourite 1 pt.

She who votes for 2 options gives her favourite 2 pts (and her 2nd choice 1 pt).

He who votes for 3 options gives his favourite 3 pts, (his 2nd choice 2 pts and his 3rd choice 1 pt).

She who votes for all 5 options gives her favourite 5 pts, (her 2nd choice 4 pts, and so on).

Page 16: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

PARTIAL VOTING IN AN MBC

If you vote for:

Number of options

1 2 3 4 5

your 1ST pref gets: 1 pt 2 pts 3 pts 4 pts 5 pts

your 2ND pref gets: 1 pt 2 pts 3 pts 4 pts

your 3RD pref gets: 1 pt 2 pts 3 pts

your 4TH pref gets: 1 pt 2 pts

your 5TH pref gets: 1 pt

Page 17: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

BORDA COUNT (BC)

A full vote = n, n-1 … 2, 1

MODIFIED BORDA COUNT (MBC)

A full vote = n, n-1 … 2, 1

A partial vote = m, m-1 … 2, 1

Page 18: THE INADEQUATE STUDY OF SOCIAL CHOICE THEORY AND ITS WORLD-WIDE CONSEQUENCES 欢迎 Peter Emerson The de Borda Institute 德博达研究所

CLOSED

QUESTIONS

SEMI-OPEN

QUESTIONS

OPEN

QUESTIONS

↑All

prefs

Borda

BC / MBC

non

Major-

C AV = alternative vote

BC = Borda Count

IRV = instant run-off

MBC = modified Borda count

STV = single transferable vote

Condorcet

(Copeland)

M

A

J

O

R

I

T

A

R

I

A

N

OSome

Approval

voting

U prefs Serial voting

Sweden*

AV = IRV = STV

N 1st

prefs

only

Weighted majority

SA, UN

Consociational

NI, Belgium

2-round voting

Norway**

T Simple majority

Ireland, UK

Twin Majority

Switzerland

Plurality

New Zealand

* a series of majority votes

** a first-round plurality and then a majority vote

1 of 2

options

1 of some options

1 or some of some options

1or some or all of all options

1st preference only Preferential

BINARY MULTI-OPTIONAL

VOTERS’ CHOICE → →

DECISION-MAKING