[EM] Get Real, Richard Moore:

Martin Harper mcnh2 at cam.ac.uk
Mon Apr 2 14:43:58 PDT 2001

Don wrote:

> Approval
> Voting is currently in vogue on this EM list.  We should try that method
> before it goes out of fashion.  Approval Voting will give the following
> results to your example:
>               17 A,   17 B,   17 C,   17 D,   17 E

No it won't. A ranking of A>B>C>D>E does not equate to an approval vote which
approves all five candidates. Nice straw man.

The correct answer is of course that we don't know who the approval winner is
unless we know how the voters rate the various candidates (as opposed to merely
ranking them).

>      Bucklin will give us: 17 A,  2 B,  3 C,  6 D,  6 E
>      So, it is candidate A, the lowest candidate of top choices, that you
> have determined shall win the election in your concocted example.  Why did
> I not see that before, yes indeed, why not?

Does anyone on this list support Bucklin? Another straw man expertly beaten

>      What is wrong here is that Bucklin violates the Golden Rule of
> Preferences, that is, later preferences are not to harm nor help earlier
> preferences.

And what basis is this golden rule coming from? What makes it golden? What
makes it better than an alternate rule: "earlier preferences are not to help or
harm later preferences". Or, say, criteria such as monotonicity?

>     One, voters of the top two candidates, D and E, would not march
> lockstep and vote for the same second choice A, and then the same third
> choice B, etc.

With 17 voters, it's entirely possible simply by random chance. If supporters
of D and E share similar political views, it's more possible. If they are
members of a distinct faction handing in block votes, then it's likely.

> Two, few of the D and E voters would choose A or B as a second or
> third choice when we consider that the voters of A and B chose D and E dead
> last, the dislike would be mutual.

I like Burger King but hate McDonalds. Would it be so amazing if someone else
liked both McDonalds and Burger King, but hated KFC?

>   Three, there is no reason for the voters of the two front running
> candidates, D and E, to make any lower choices.

In IRV this is correct. In other methods it is not.

> Their two candidates are head and shoulders above the three lowest
> candidates,

Says who? They are head and shoulders above in first place support - but first
place support isn't everything - if it was, then we should stick with

> it is of no interest to these voters which of the three is to be the last
> candidate.

Maybe they particularly hate someone and want to do everything possible to keep
them out. Perhaps one of the candidates is an anti-semitist and they are a jew.
Perhaps one of them doesn't believe in global warming, and they're a
green-fanatic. Point is more people vote to keep someone they dislike out than
to get someone they like in.

>    The jury is in, candidate D is the winner [of a modified example which is
> supposedly more realistic], but we already knew that.

Even if I was to accept your reasoning... Given that approval requires less
changes to the voting system, is easier to count, simpler to vote, and cheaper
to implement - and according to you gives exactly the same winner as IRV in
'realistic' situations... why exactly would you choose IRV over Approval?

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