[kibwen]

I would be sensitive to the "TPC under RCV are more likely to be extremists" argument were it not for the fact that FPTP has already allowed profound extremism in one of our two parties, and since FPTP is so anti-competitive it means that it's extremely difficult to combat. I'll take a system that makes parties more competitive, which non-FPTP systems all do.

[nickff]

I'm not sure what your definition of 'extremist' is. If either major party is getting close to 50% of the votes, it must be quite mainstream. I don't have to like it, and I may in fact find it abhorrent, but that has nothing to do with extremism.

[snewman]

A common scenario in many locations in the US:

A district tilts heavily toward one of the two main parties -- it is a "safe" district for that party. The candidate nominated by that party in the primary election is nearly certain to win the general election. If the candidate is highly extremist / flawed, they might lose, but party affiliation is sufficiently strong nowadays (aka the electorate is sufficiently polarized) that a candidate can be pretty far to one extreme -- farther out than the bulk of the electorate -- and still win.

Meanwhile, there is a tendency for the more centrist voters in both parties to skip the primary. Thus, the candidate who survives the primary is often relatively extreme.

The result is that the victor of the general election is often to the extreme side of not only the electorate as a whole, but the membership of their party.

To oversimplify, imagine that political views fall on a one-dimensional spectrum ranging from 0 to 1, and the electorate consists of:

  - 40% at 0.4 (center-left)
  - 30% at 0.6 (center-right)
  - 30% at 0.8 (heavy right)

In the primary, center-right voters are under-represented, and a candidate at or beyond 0.8 has an excellent chance of being nominated. Then in the general election, at least 2/3 of the center-right voters are likely to swing toward that candidate (because of polarization / strong party affiliation).

[nickff]

Looking at your spectrum, I'd see the same distribution as:

- 40% left

- 30% center

- 30% right

Any rating of 'how far' someone is along the spectrum is arbitrary, as the spectrum itself is arbitrary. I wouldn't see any extremism either.

[snewman]

Agreed, the spectrum ultimately is arbitrary. I was thinking in terms of a spectrum normalized to the country as a whole. In a particular district, you often have a breakdown that is off-center relative to the overall nation (of course that can be in either direction).

And in any case, the key point is that the primary process can lead to a candidate taking office who is well off-center even within their district.

[kibwen]

Amusingly, upthread you and I are talking about whether encouraging more people to vote leads to better outcomes, and this is an example where the answer is yes: a candidate can be both an extremist and receive 50% of the vote if, as in is true in the US, less than half the eligible electorate actually votes. The current president was elected on the backs of 25% of eligible voters; does that make him an extremist candidate even by the standards of the US electorate? If we had more data on account of more Americans asserting their preferences, then we could actually determine that.

[nickff]

I think that's a sign that each of us has nuanced views!

'Extremist' is a bit of a slippery fish; I can't imagine calling something with even 10% support 'extremist'. If I had to draw a line, it would probably be that the sum of all 'extreme position support' would have to be less than 5% for a given subject. That is not to say that positions with >5% support are necessarily correct or conscionable.

[pessimizer]

For "extremism" to be anything but a meaningless slur, it has to at least include in its meaning "not common."

[danaris]

I don't care how common it is; anyone advocating for genocide is an extremist.

There is an absolute scale, just like there is at least some absolute morality.