Chance, not ideology, drives political polarization

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Ever-widening divisions between Democrats and Republicans are believed to reflect deeply rooted ideological differences, but a new study points to a radically different interpretation: it may be mostly a matter of luck.

It's a phenomenon that Michael Macy, Cornell University professor and director of the Social Dynamics Laboratory, calls an "opinion cascade"—in which partisans pile onto whatever emerging position they identify with their party. Macy is author of "Opinion Cascades and the Unpredictability of Partisan Polarization," published Aug. 28 in Science Advances.

Social scientists have long wondered how political partisanship develops, and even more confusing is the tendency of U.S. political parties to radically shift platforms.

Macy asks: "Why have the major shifted positions on issues like , balanced budgets, legalization of marijuana, same-sex marriage and trust in science? And how is it that voters on both sides often have contradictory positions on and ?"

Macy's team looked for answers by conducting an experiment in which they re-created the early days of opinion formation to see how the cards might have fallen differently had early movers held different arbitrary opinions.

Video presentation of the study. Credit: Michael Macy, Sebastian Deri, Alex Ruch, and Natalie Tong (Cornell University)

The researchers split more than 2,000 Democratic and Republican volunteers into 10 "," each isolated from the others. Within each world, participants took turns filling out an to indicate whether they agreed or disagreed with a series of unfamiliar political and cultural issues. In two of the 10 worlds, the survey was private, but in the other eight, whenever a partisan took a position on a given issue, all other participants in their world saw a real-time update of how each party was leaning.

The results showed how a handful of early movers can trigger a cascade in which later partisans pile on to their party's newly emerging position, leading eventually to large political differences. The big surprise was that the party that supported the issue in one world was just as likely to oppose the issue in another world.

"In one world, it was Democrats who favored using AI to spot online criminals, and in another world it was Republicans," he said. "In one world, Democrats favored classic books, and in another world, Republicans favored the classics. In one world, Democrats were more optimistic about the future and in another world, it was Republicans."

Macy hopes that these findings might help civilize the political discourse.

"In our world, political divisions are so fiercely defended," Macy said. "The two sides get very worked up, which would seem to indicate that positions are deeply rooted fundamental divisions. But our study suggests that these positions may just be identity markers, like bumper stickers, the result of cascades that propelled people into a with which they came to emotionally identify.

"Learning that the two parties could just as easily have switched sides," he said, "might encourage people to re-examine their positions and listen to the views of people with whom they sharply disagree."


Explore further

Partisanship runs deep in America - even among 'independents'

More information: M. Macy el al., "Opinion cascades and the unpredictability of partisan polarization," Science Advances (2019). DOI: 10.1126/sciadv.aax0754 , https://advances.sciencemag.org/content/5/8/eaax0754
Journal information: Science Advances

Provided by Cornell University
Citation: Chance, not ideology, drives political polarization (2019, August 28) retrieved 17 October 2019 from https://phys.org/news/2019-08-chance-ideology-political-polarization.html
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Aug 28, 2019
humans are not rational beings...

Aug 28, 2019
The Ancient Greek founders of mob rule of the majority did not have political parties, but their 'comrades' associations' - hetairea / hetairikon - were as harmful in their power seeking, enough that eisangelia - legal denunciation - was enacted.

Aug 28, 2019
There is no accident that Rick is contained within the word politics.

Aug 28, 2019
Humans respond oppositely to input...

Aug 28, 2019
What would Saul Alinsky say?

Aug 28, 2019
There is some element of chance, but there is also an element of calculation, and I believe the latter outweighs the former.

Aug 28, 2019
Citizens of the United States live better than 93% of the rest of the world. I am 72 years old and was taught in school that it's our multi party system tham makes America great.
We have so many people that don't realize how good they have it, that they are intent on rocking the boat till the boat tips over.

At 93%, our current and past leaders along with our government's agencies must be doing a whole lot right.
Sometimes people are so dumb. I told a guy about the 93% yesterday, and all he could say is we can do better. We feed our dogs better than most people in other countries feed their kids. That wealth is what makes a lot of other countries hate us, plus it is the major reason why we have so many people wanting to immigrate here.
We don't need better living conditions with more wealth, what we need is fewer people trying to tip the boat over.

Aug 29, 2019
Sorry, I meant to say tick and not rick.

Aug 29, 2019
Tribalism destroys objectivity. Membership entails defending whatever abstract credos and rituals that define the tribal identity. Does god have a mother? Is jesus superhuman or flawed god? Who is Mohammad's rightful heir? Objectively these opinions are meaningless but the tribes who ascribe to them have been willing to defend them to the death, and to murder without remorse.

The only thing that matters to the committed tribalist is gaining advantage over adversaries. And they are willing to lie and cheat to do it, most often to themselves.

Most all humans are tribal. This is why we are so easy to manipulate, and why systems of governance like democracy can never be allowed to govern. Which is why they never have and they never will. Like religion their job is only to manipulate.

Aug 29, 2019
""In one world, it was Democrats who favored using AI to spot online criminals, and in another world it was Republicans,"

A real-life example...

Trump diverts FEMA money to border crisis
"Sen. Jon Tester of Montana, the ranking Democrat on the Senate Appropriations Subcommittee on Homeland Security, also expressed reservations about the administration's plan.
"I have grave concerns about DHS's proposed end-run around laws passed by Congress that would drain millions from agencies tasked with protecting the homeland from security threats and natural disasters"

-But did you know?

"Democrats slam President Trump for diverting FEMA funds to the border, but then-President Barack Obama did the same thing in 2014"

-We are subject to the same sort of manipulation every day and we willingly accept it because it plays to our fundamental nature as tribalists.

Aug 29, 2019
"Macy hopes that these findings might help civilize the political discourse."

-But the current discourse is being intentionally inflamed, polarized, tribalized. Tribalists are not going to make the decision personally to be rational because it makes them look like they are capitulating. Apostacy is punished most severely.

Aug 29, 2019
Well TheGhostofOtto1923 only 3 posts in a row this time? I don't know what you said but a dollar to a doughnut you were trying to sound educated by saying the word tribalism 2 zillion times. I just wish you could convince yourself you are not a moron, that way your long windedness would cease. I guess you just have mental inadequacy issues.

Aug 31, 2019
Tribalism destroys objectivity. Membership entails defending whatever abstract credos and rituals that define the tribal identity.


On the contrary. It's rational for people to support the opinions of their own group, in order to get the group to support theirs, and to present a unified front against the competition.

As individuals, people have few ways of making other people behave. You can threaten someone with violence and retribution, you can buy them off, or you can trade. These "opinion cascades" are examples of the latter: public conformity to what is perceived to be the group opinion is social currency - I scratch your back, you scratch mine.

This has nothing to do with "tribalism". Any time people organize into groups of any kind, group dynamics take over.

Aug 31, 2019
Not surprising.

The Ancient Greek founders of mob rule of the majority


Also called democracy, 'the worst system besides every other tried'. And it is winning the world over, likely because it works.

At 93%, our current and past leaders along with our government's agencies must be doing a whole lot right.


US economy is founded on genocide, slavery and exploitation. There is nothing inherently good in that.

That wealth is what makes a lot of other countries hate us, plus it is the major reason why we have so many people wanting to immigrate here.


A self contradicting sentence - what is it, "hate" or "want"? In statistics US is not hated, but disliked because of such arrogance and power play as you display (refusing immigration). US has few immigrants these days due to that, about 1 % of your population vs Germany, Sweden et cetera 10 %. EU would be in trouble if economic work immigrants not wanted to move here. US *will* be in trouble as your peeps grow old.


Aug 31, 2019
US economy is founded on genocide, slavery and exploitation.


You are out of your gourd. Is one man different from another? All countries are founded on the same things just to different degrees. I think, by thinking the way you do, you are betraying you children and grandchildren and you don't even care.

US has few immigrants these days due to that,


And what is wrong with a country deciding who can come into it? That once again is the way all countries are.

Aug 31, 2019
Simple easy and obvious: Exxon and Shell propaganda (when they knew better, as demonstrated from their internal documents) influenced one political party to support them, dividing the nation. This is not "random chance." It's a coldly calculated political ploy, for which they are paying in public respect and from which they are vigorously trying to hide.

Sep 01, 2019
On the contrary. It's rational for people to support the opinions of their own group, in order to get the group to support theirs, and to present a unified front against the competition
That's right. Whether objectively they're right or wrong. That's my point. That's the point of the article.
This has nothing to do with "tribalism". Any time people organize into groups of any kind, group dynamics take over
Again, right. But its CALLED tribalism.

You dont understand what tribalism is do you? Even after I've been posting about it for years. So explain what you think it is.

Sep 01, 2019
US economy is founded on genocide, slavery and exploitation. There is nothing inherently good in that
If I'm not mistaken, torbjorn is from a country founded by vikings?

Sep 03, 2019
SpookyOtto the Nazi hater of humanity vomits his stock phrases. Otto habitually posts the same tired old boring comments year after year, about women and the same tired old bullshlt about Tribal Dynamics, thinking that these two themes will make all the readers think that Otto is so full of wisdom and knows more than anyone else.

Such false pride in oneself is Otto's undoing, besides all of his past sins that are recorded, and for which he will pay when we take his already damned soul up to where it will burn with horrible pain for all eternity. Otto's alleged 'ghost' will find out soon enough that we don't make deals.

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