Which voting system is the best? - Alex Gendler

1,249,184 views ・ 2020-06-11

TED-Ed


Please double-click on the English subtitles below to play the video.

Translator: Rastbêjê Çalî Reviewer: Daban Q. Jaff
00:06
Imagine we want to build a new space port
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wêna bikin ku em dixwazin bendergehekê valagehî ( fezayî) yê nû ava bikin
00:09
at one of four recently settled Martian bases,
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li yek ji çar bingehên martî, yên ku nû bicîh bûne,
00:13
and are holding a vote to determine its location.
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û em ji bo diyarkirina cihê wê dengdanê dikin,
00:16
Of the hundred colonists on Mars, 42 live on West Base, 26 on North Base,
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ji sed dagîrkerên li merîxê, 42 li bingehê rojava, 26 li bingehê bakûr,
00:23
15 on South Base, and 17 on East Base.
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15 li bingehê başûr, û 17 li bingehê rojhilatê,
00:28
For our purposes, let’s assume that everyone prefers the space port
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ji bo meremên me, em pêdvî bikin ku her kes benderê valagehê bibijêre
00:32
to be as close to their base as possible, and will vote accordingly.
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ku gengaz be nêzîkî bingehê wan bin, û wê li gorî wê deng bidin.
00:37
What is the fairest way to conduct that vote?
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awayê herî dadperwer ji bo pêkanîna wê dengdanê çi ye?
00:40
The most straightforward solution would be to just let each individual
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çareseriya herî rasterast wê tenê ew be ku bila her kesek be
00:44
cast a single ballot, and choose the location with the most votes.
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sindoqekê bavêjin, û cihê ku herî zêde deng digire hilbijêrin.
00:48
This is known as plurality voting, or "first past the post."
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ev wekî dengdana pirjimariyê tê zanîn, an êkem posta paşîn,
00:54
In this case, West Base wins easily,
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di vê rewşê da, bingehê rojava bi hêsanî bi ser dikeve,
00:57
since it has more residents than any other.
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ji ber ku ji yên din zêdetir niştecihên wê hene.
00:59
And yet, most colonists would consider this the worst result,
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û hê jî, piranîya dagirkeran wê vî encamê xirab li berçav bigrin.
01:04
given how far it is from everyone else.
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tê dayîn ku ew ji her kesê din çiqas dûr e.
01:07
So is plurality vote really the fairest method?
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ji ber vê yekê gelo bi rastî dengên pirjimariyê rêya herî dadperwere?
01:12
What if we tried a system like instant runoff voting,
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heke em pergalek mîna dengdana tavilê ya tavilê ezmûn bikin,
01:15
which accounts for the full range of people’s preferences
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ku bi tevahî hevyazên mirovan di hijmêre,
01:19
rather than just their top choices?
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ne tenê ji hilbijartinên wan ên jorîn?
01:21
Here’s how it would work.
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li vir ew ê çawa bi xebite.
01:23
First, voters rank each of the options from 1 to 4,
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destpêkê, hilbijêr her yek ji vebijarkan ji 1-ê heya 4-an rêz dikin,
01:27
and we compare their top picks.
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û em hilbijartinên wan ên jorîn didin ber hev.
01:29
South receives the fewest votes for first place, so it’s eliminated.
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başûr ji bo pileya yekem herî kêm deng digire, ji ber vê yekê di hête hilwişandin.
01:34
Its 15 votes get allocated to those voters’ second choice—
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ev 15 dengin ji bo hilbijartina duyemîn a wan hilbijêran di hête veqetandin-
01:39
East Base— giving it a total of 32.
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bingehê rojhilatê, bi tevahî 32-an dide wê.
01:43
We then compare top preferences and cut the last place option again.
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paşî em hevyazên jorîn didin ber hev û dîsa vebijarka cihê paşîn qut dikin.
01:49
This time North Base is eliminated.
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vê carê bingehê bakur di hête rakirin.
01:51
Its residents’ second choice would’ve been South Base,
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hilbijartina duyemîn a nîştecîhên wê dê bingehê başûr bûya,
01:54
but since that’s already gone, the votes go to their third choice.
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lê ji ber ku ew ji xwe çû, deng diçin hilbijartina wan a sêyemîn.
01:59
That gives East 58 votes over West’s 42, making it the winner.
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ku 58 dengan dide rojhilat li ser 42-ên rojava, wê serkeftî dike.
02:05
But this doesn’t seem fair either.
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lê ev jî dadmend xuya nake.
02:08
Not only did East start out in second-to-last place,
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ne tenê rojhilat di cihê duyemîn-dawiyê de dest pê kir,
02:11
but a majority ranked it among their two least preferred options.
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lê piraniyek ew di nav du vebijarkên xwe yên herî kêm bijarte de rêz kir,
02:16
Instead of using rankings, we could try voting in multiple rounds,
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li şûna bi karanîna rêzikan, em dikarin di pir geran de dengdanê ezmûn bikin,
02:20
with the top two winners proceeding to a separate runoff.
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bi du serkeftiyên jorîn re derbasî pêş birkek cuda dibin.
02:25
Normally, this would mean West and North winning the first round,
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bara pitir, ev tê vê wateyê ku rojava û bakur tûra êkê bi dest dixin,
02:29
and North winning the second.
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û bakur ya dûyê qezenc kirin.
02:30
But the residents of East Base realize
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lê nîştecihên bingehê rojhilatê tê gihiştin
02:33
that while they don’t have the votes to win,
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demê ku dengên wan nebin ji bo serkeftinê
02:36
they can still skew the results in their favor.
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ew hîn jî dikarin encaman di berjewendiya xwe de bişkînin.
02:39
In the first round, they vote for South Base instead of their own,
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di tûra êkê da, ew li şûna xwe dengê xwe didin başur,
02:43
successfully keeping North from advancing.
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bi awayekê serkeftî bakûr ji pêşveçûnê dûr dixe.
02:46
Thanks to this "tactical voting" by East Base residents,
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bi saya vê dengdana taktîkî ya niştecihên bingehê rojhilatê,
02:50
South wins the second round easily, despite being the least populated.
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başûr tûra dûyê bi hêsanî qezenc dike, digel ku nifûsa herî kêm e jî.
02:55
Can a system be called fair and good if it incentivizes lying
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gelu dibe ji pergalekê re dadperwer û baş bê gotin heke ew hanî derewkirinê bide,
02:59
about your preferences?
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li ser hevyazên xwe?
03:01
Maybe what we need to do is let voters express a preference
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dibe ku ya ku divê em bikin ev e ku bila hilbijêr hevyaza xwe diyar bikin
03:05
in every possible head-to-head matchup.
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di her pêk hînanek gengaz de serî-bi-serî ( rûbirûbûn)
03:08
This is known as the Condorcet method.
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ev wekî rêbaza kondorsêtê tê zanîn.
03:11
Consider one matchup: West versus North.
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pêşbirkekê li berçav bigrin: rojava li hevber bakûr.
03:15
All 100 colonists vote on their preference between the two.
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her 100 dagîrker li ser hevyaza xwe ya di navbera her duyan de deng didin.
03:18
So that's West's 42 versus the 58 from North, South, and East,
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anku ev ya rojava ye 42 li hevber 58 ya li bakûr, başûr û rojhilat,
03:23
who would all prefer North.
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kî dê bakûr hemî yê hevyaz bike.
03:25
Now do the same for the other five matchups.
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niha heman tişt ji bo pênc pêkanînên din jî bikin.
03:29
The victor will be whichever base wins the most times.
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yê ku bingehê wî herî zêde bi ser bikeve wê bibe serkeftî.
03:32
Here, North wins three and South wins two.
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li vir, bakûr sê ya û başûr du yan qezenc dike
03:36
These are indeed the two most central locations,
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bi rastî ev du deverên herî navendî ne,
03:40
and North has the advantage of not being anyone’s least preferred choice.
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û bakûr xwediyê sûd ê ye ku ne kesek e ku herî kêm hilbijartinek ê hevyaz dike.
03:45
So does that make the Condorcet method an ideal voting system in general?
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ji ber vê yekê gelo ew rêbaza kondorsêt ê bi gelemeperî dike pergalek dengdana nimûneyî?
03:50
Not necessarily.
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pêdvî nake.
03:53
Consider an election with three candidates.
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hilbijartinek bi sê berjengan li berçav bigrin.
03:55
If voters prefer A over B, and B over C, but prefer C over A,
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heke hilbijêr A-yê ji B-yê, û B-yê ji C-yê hevyaz bikin, lê C-yê ji A-yê re hevyaz bikin,
04:01
this method fails to select a winner.
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ev rê têkçû ku serkeftî hilbijêre.
04:04
Over the decades, researchers and statisticians have come up with
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di deh salan de, lêkoler û hijmarzan derketin
04:08
dozens of intricate ways of conducting and counting votes,
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bi dehan awayên tevlihevên meşandin û hijmartina dengan,
04:12
and some have even been put into practice.
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û heta hindek jî xistine nav rahênan an,
04:14
But whichever one you choose,
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lê hûn ê kîjan hilbijêrin,
04:16
it's possible to imagine it delivering an unfair result.
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gengaz e ku meriv wêna bike ku ew encamek ne dadperwer derxîne.
04:21
It turns out that our intuitive concept of fairness
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der dikeve holê ku têgeha me ya pêjinîdar a dadperweriyê
04:25
actually contains a number of assumptions that may contradict each other.
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bi rastî çend pêşbînî hene ku dibe ku dijberî hev bin.
04:29
It doesn’t seem fair for some voters to have more influence than others.
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ji bo hin hilbijêran dadperwer xuya nake ku ji yên din bêtir xwedî bandor bin.
04:33
But nor does it seem fair to simply ignore minority preferences,
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lê ne jî rast xuya dike ku meriv tenê hevyazên hindikahiyan paşguh bike,
04:38
or encourage people to game the system.
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an mirovan teşwîq bikin ku bi pergalê re bi lîzin.
04:41
In fact, mathematical proofs have shown that for any election
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di rastiyê de, ezmûnên bîrkariyê ji bo her hilbijartinê ew diyar kirine
04:45
with more than two options,
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bi du vebijarkan re,
04:47
it’s impossible to design a voting system that doesn’t violate
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ne pêkane ku meriv pergalek a dengdanê ya ku binpê nake sêwiran bike
04:51
at least some theoretically desirable criteria.
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qe nebe hindek pîvanên dîtnekî yên balkêş.
04:55
So while we often think of democracy as a simple matter of counting votes,
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ji ber vê yekê gelek caran demê em demokrasiyê wekî mijarek a hêsan a jimartin a dengan difikrin,
05:00
it’s also worth considering who benefits from the different ways of counting them.
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her wiha hêja ye ku meriv ji awayên cuda yên hijmartin a wan sûd werbigire.
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