Chapter 27

The Upside-Down Bell Curve

Looking at the blue line, the average human height is about 66 inches, with a range of the number taller and shorter than the average moving down and away from the average in both directions, making the shape of a bell. Note the red curve is a perfect bell curve and is the normal distribution.  So the actual distribution of human height is quite close to the normal bell curve.

Let’s look at the distribution of political views in the US from the perspective of Left and Right as presented in Surveys conducted by the Pew Research Center. Particularly, let’s look at the Bell curves from 1994 to 2017 regarding the medians of Democratic and Republican views in the USA, as presented in Political Polarization, 1994-2017, Pew Research Center, October 20, 2017, except for text added in italic:

Democrat and Republican overlap. Overall it looks like a bell.

Democrat and Republican overlap. Overall it looks like a bell.

Democrat and Republican overlap. Overall it looks like a bell.

Are Democrats and Republicans starting to separate or is it still a bell?

Democrats and Republicans are separating

Democrats and Republicans have significantly separated, there are now two peaks and it no longer looks like a bell.

The following information is from The Partisan Divide on Political Values Grows Even Wider, Pew Research Center, October 5, 2017, except for informaton in italic.

Partisan divides over political values widen

The gap between the political values of Democrats and Republicans is now larger than at any point in Pew Research Center surveys dating back to 1994, a continuation of a steep increase in the ideological divisions between the two parties over more than a decade.

The subsequent chapters explore Americans’ attitudes across individual political values and policy issues, in most cases including data dating back to the late 1990s or early 2000s. In nearly every domain, across most of the roughly two dozen values questions tracked, views of Republicans and Republican-leaning independents and those of Democrats and Democratic leaners are now further apart than in the past.

While the overall partisan gap across a variety of political values has steadily grown, the dynamic underlying the growing gap differs across issue areas. In some cases, the gap has grown because the parties have moved in different directions, with growing shares of Democrats taking liberal positions and increasing shares of Republicans taking conservative positions. But in other areas, shifts are greater among one set of partisans than another.

In a few issue areas, notably views of homosexuality and of immigrants, public opinion in both parties has clearly shifted in a more liberal direction over the past several decades. Nevertheless, the partisan gaps on both of these values have gotten wider over the past two decades, as the long-term shifts are more pronounced among Democrats than Republicans.

Overall partisan gap widens over two decades

Note the gap starts to widen between 1999 and 2004, which is the time, the year 2000, that Andersen claimed as the first unequivocal year of Fantasyland.

The 10 political values questions (shown at the bottom of this page) have been asked together in surveys seven times since 1994. On average, there is now a 36-percentage-point difference between Democrats and Republicans across these questions. The current gap represents a modest increase in the partisan divide over the past two years (from 33 points in 2015), but it is substantially wider than two decades ago (the gap was just 15 points in 1994).

For instance, overall, on this scale of 10 political values, the median (middle) Republican is now more conservative than 97% of Democrats, and the median Democrat is more liberal than 95% of Republicans. By comparison, in 1994 there was substantially more overlap between the two partisan groups than there is today: Just 64% of Republicans were to the right of the median Democrat, while 70% of Democrats were to the left of the median Republican. Put differently, in 1994 23% of Republicans were more liberal than the median Democrat; while 17% of Democrats were more conservative than the median Republican. Today, those numbers are just 1% and 3%, respectively.

Partisan Animosity

As Republicans and Democrats have moved further apart on political values and issues, there has been an accompanying increase in the level of negative sentiment that they direct toward the opposing party. Partisans have long held unfavorable views of the other party, but negative opinions are now more widely held and intensely felt than in the past.

Among members of both parties, the shares with very unfavorable opinions of the other party have more than doubled since 1994.

More negative views of the opposing party – and its members

As noted in the Center’s 2014 study of political polarization, Republicans and Democrats have long had negative opinions of the other party. But in the past, more partisans had mostly unfavorable views than very unfavorable views.

This is no longer the case. About eight-in-ten Democrats and Democratic-leaning independents (81%) have an unfavorable opinion of the Republican Party, based on an average of surveys conducted this year – with 44% expressing a very unfavorable view. Two decades ago, a smaller majority of Democrats (57%) viewed the GOP unfavorably, and just 16% held a very unfavorable view.

The share of Republicans with highly negative opinions of the Democratic Party has followed a similar trajectory. Currently, 81% of Republicans and Republican leaners have an unfavorable impression of the Democratic Party, with 45% taking a very unfavorable view. In 1994, 68% of Republicans had a negative view of the Democratic Party; just 17% had a very unfavorable opinion.

Let’s compare the Left and Right ideological curves over the last 25 years

Information below is from: Political Polarization in the American Public, Pew Research Center, June 12, 2014

The graphic below shows the extent to which members of both parties have become more ideologically consistent and, as a result, further from one another. When responses to 10 questions are scaled together to create a measure of ideological consistency, the median (middle) Republican here is more conservative than nearly all Democrats (94%), and the median Democrat is more liberal than 92% of Republicans.

As can be seen above, in the 2014 political environment, party (and partisan leaning) predicts ideological consistency more than ever before, and this is particularly the case among the politically engaged. Among Americans who kept up with politics and government and who regularly vote, fully 99% of Republicans were more conservative than the median Democrat, while 98% of Democrats were more liberal than the median Republican. While engaged partisans have always been ideologically divided, there was more overlap in the recent past; just 10 years ago these numbers were 88% and 84%, respectively. Here we see the start of significant polarization.

Another PEW Survey was done in 2017:

Here is a graph of the politically engaged in 2017. Here the upside down bell curve becomes prominent.

From: Political Polarization, 1994-2017, Pew Research Center, October 20, 2017.

Note in 1994 there is no split in the curve between the Left and the Right, in 2004 we can see a split starting, by 2014 we can see an increase in polarization as the upside-down bell curve shows itself, and by 2017 the upside-down bell curve becomes prominent. This shows us the polarization of the Left and Right and the upside-down bell curve now present in the USA. If a bell curve is considered normal, why do we as a society among the politically active and influential have an upside-down bell curve, is that abnormal?  Why are we so polarized?  The answer lies in the human brain and neurological evolution. It’s in our genes, it’s been in our genes for a very long time: cognitive bias probably developing over the course of late mammalian evolution and present in Australopithecus; to confirmation bias in Homo habilis; to the tribe and argumentative theory, where truth doesn’t matter, winning the argument and gaining power does in Homo erectus; all the while generating the tribal ethos resulting in the warrior ethos that lead Homo sapiens out of Africa 70,000 years ago to dominate the world. Our genetically evolved and present cognitive, confirmation, tribal and argumentative biases shape our polarized perceptions of the world around us, and our warrior ethos finds others of similar mind to battle the opposing party.  Do we have to be this polarized?  Can individual human consciousness be aware of this predisposition and keep it in check, putting value in moderation, reason and truth? Can your neuroreality be neureal and rather than unneural? Ben Franklin addressed that question after the Constitutional Convention: “We’ve given you a republic, can you keep it?” Perhaps if we depolarize, get back to the normal bell curve, become more neureal, and become more centrist as a Nation, the answer will be yes.

Here’s another example of the upside-down bell curve regarding the political activism gap with regard to political donation, again from  Political Polarization in the American Public, Pew Research Center, June 12, 2014, see the graph below:

Many of those in the center remain on the edges of the political playing field ... while the most ideologically oriented and politically rancorous Americans make their voices heard.

The rise of ideological uniformity has been much more pronounced among those who are the most politically active. Today, almost four-in-ten (38%) politically engaged Democrats are consistent liberals, up from just 8% in 1994. The change among Republicans since then appears less dramatic – 33% express consistently conservative views, up from 23% in the midst of the 1994 “Republican Revolution.” But a decade ago, just 10% of politically engaged Republicans had across-the-board conservative attitudes

On measure after measure – whether primary voting, writing letters to officials, volunteering for or donating to a campaign – the most politically polarized are more actively involved in politics, amplifying the voices that are the least willing to see the parties meet each other halfway.

These are among the findings of the largest study of U.S. political attitudes ever undertaken by the Pew Research Center. Data are drawn from a national telephone survey of 10,013 adults, conducted from January through March of this year, and an ongoing series of follow-up surveys. This rich dataset, coupled with trends and insights from two decades of Pew Research Center polling, reveals a complex picture of partisan polarization and how it manifests itself in political behaviors, policy debates, election dynamics and everyday life.


Where are you on the political spectrum? Take the Ideology Consistency Scale Test below that was used in these surveys.  I came out with a -1.

Throughout this report we utilize a scale composed of 10 questions asked on Pew Research Center surveys going back to 1994 to gauge the extent to which people offer mostly liberal or mostly conservative views across a range of political value dimensions. In short, while there is no ex-ante reason for people’s views on diverse issues such as the social safety net, homosexuality and military strength to correlate, these views have a traditional “left/right” association, and the scale measures this growing correlation over time.

The individual questions in the scale are shown above.

Individual questions were recoded as follows: “-1” for a liberal response, “+1” for a conservative response, “0” for other (don’t know / didn't answer, etc...) responses. As a result, scores on the full scale range from -10 (liberal /left responses to all 10 questions) to +10 (conservative/right responses to all 10 questions). For analytical purposes, respondents are grouped into one of five categories, which are used throughout the report, as follows:

- Consistently conservative (+7 to +10), aka Far Right
- Mostly conservative (+3 to +6), aka Moderte Right
- Mixed (-2 to +2), aka Cenrtist
- Mostly liberal (-6 to -3), aka Moderate Left
- Consistently liberal (-10 to -7), aka Far Left

To put these figures in perspective, a respondent offering five liberal and five conservative views, or six of one and four of the other, would be considered a Centrist. Someone offering seven conservative and three liberal responses, or eight and two, would be considered “Moderate Right.” And any respondents offering nine conservative and one liberal response, or all ten conservative, would be considered “Far Right.” Since some people do not answer every question, other combinations are possible.

Let’s look at the progression of the politically engaged graphs over the past 25 years, bold added for emphasis.

The regular bell curve refers to a normal distribution of a value across a range. Let’s look at the distribution of human height: 

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