The evolutionary psychology of the myside bias

Andreas Hofer
6 min readOct 26, 2021

The Bias That Divides Us: The Science and Politics of Myside Thinking (2021)

by Keith Stanovich is a fascinating book that illustrates impressively how both the political left and right are prone to the myside bias, a special case of the confirmation bias.

When it comes to the myside bias, people are quick to detect logical errors in the opponent side argumentation, but not in their own:

In fact, each side in our partisan debates often argues-convincingly-how positions on the other side are inconsistent and aligned in a seemingly incoherent manner, and such arguments are often quite effective. In the abortion debate, it is common for pro-choice advocates to point out the inconsistency of the pro-life advocates who want to preserve the life of the unborn but not the life of someone on death row. This argument is often effective and compelling, but so is the counterargument by pro-life advocates, who point out the inconsistency of their pro-choice opponents in opposing the death penalty but supporting abortion-in seeming to find the deaths of criminals-but not the deaths of the unborn-unacceptable. When pro-choice advocates argue that many innocent people have been executed, the pro-life advocates counter that all of the unborn are innocent. Thus, when it comes to inconsistency on the part of their opponents, both pro-choice and pro-life advocates seem to have compelling arguments.

I am a liberal, and indeed I find it strange that I might find myself arguing for abortion of innocent lives and against the death penalty for a serial killer. As a liberal, I also tend to find conservatives too ingroupish and anti-science. Again Stanovich teaches me a lesson:

When, however, Chambers, Schlenker, and Collisson (2013) measured the degree of tolerance and warmth liberal subjects displayed toward groups whose values conflicted with liberal values (businesspeople, Christian fundamentalists, the wealthy, the military), they found that liberal subjects displayed as much out-group dislike as conservative subjects did. Ideological similarity strongly predicted group liking, with correlations greater than .80.

Stanovich does a good job in presenting a balanced view: Both sides can be equally

Being an ardent proponent of Evolutionary Psychology I have seen liberal often attacking research on the differences between the genders, for example.

However, I think Stanovich falls into the same trap he argues against: he is trying to be too politically correct. While it’s true that we all fall prey to the myside bias, we aren’t the same and there are some fundamental differences Stanovich downplays. Moreover, he doesn’t really come up with any ideas for the origins of our “sides” and downplaying the differences only prevents finding any.

Anticipating Mercier and Sperber (2011) in some ways, Klayman (1995, 411) argues that “when other people lack good information about the accuracy of one’s judgments, they may take consistency as a sign of correctness”; he points to the many characteristics of myside argumentation (e.g., consistency, confidence) that can bootstrap social benefits to the individual and group. Dan Kahan’s discussions of his concept of identity protective cognition (Kahan 2013, 2015; see also Kahan, Jenkins-Smith, and Braman 2011; Kahan et al. 2017) likewise suggest other potential mechanisms for myside bias to confer evolutionary benefit by facilitating group cohesion.

If group cohesion (or tribalism in its original sense) was the driver of the myside basis, we wouldn’t be seeing the same pattern all over the world. It would be village against village, country against country. Tribalism has been getting worse due to globalization, not because one community is up against another as it was true mostly in the past, but because trends in either direction have been globally amplified.The contents of our personal values would matter less than the values of our group. What we see, however, is the reverse pattern: people actively FINDING their tribes, rather than siding with the one they were born into. Stanovich writes about the liberal bias in academia:

A survey of 500 arts and science faculty members at Harvard (Bikales and Goodman 2020) found that less than 2 percent identified themselves as conservative or very conservative, compared to more than 38 percent identifying themselves as very liberal and almost 80 percent as liberal or very liberal.

If liberals and conservatives are equally rational and science-loving, where does this bias come from? The answer is simple, they aren’t equally interested in science and their rationality may really be following a different evolutionary logic. As a liberal living in the countryside, I have found other people of myside far more often online than in my neighbourhood. Liberals tend to clusters in certain areas and liberal biases exist in:

  • Science and universities
  • Journalism
  • Literature
  • Arts in general, including Hollywood
  • Environmentalism
  • Cities (vs. suburbs and countryside)
  • Non-mainstream online communities (e.g. Reddit, Quora)
  • Some hi-tech companies, especially in Silicon Valley

Apart from some key political issues like gun control, abortion and taxation, liberals and conservatives differ in many traits and lifestyle choices, such as travelling, learning foreign languages, interest in foreign cultures, and even food preferences. Studies have shown that our political preferences already manifest in childhood and are partially genetic. Conservative children are more obedient and cautious, whereas liberal children are less obedient and more explorative.

So, where do our tendencies come from? Looking at different cultures around the world, we can see that liberal values can be found in most hunter-gatherer societies and conservative values can be found in most agricultural societies.

In fact, researchers have found that the longer history of agriculture an area had the more conservative (or “tight” in Michelle Gelfand’s terminology) the population is, whereas hunter-gatherers like the Inuit or Hazda tend to be “loose”, i.e. low in rule enforcement and high in personal freedom.

So, our myside bias is at least partially rooted in our evolutionary history. Returning to the example above: hunter-gatherers have fewer children (4-year intervals) than farmers (2-year intervals) as additional children would threaten the survival of the other children. Infanticide (the forager equivalent of abortion) is therefore not uncommon. Most foragers have sex taboos after the birth of a child to avoid further offspring in quick succession. Punishment among farmer societies also tends to be much more severe than among hunter-gatherers. When there is conflict, hunter-gatherers leave their band and join a new one. Farmers on the other hand tend to enforce conformism and adherence to rules. Farmers tend to live with the same community for all of their lives, whereas changing bands is very common in foragers.

Our myside biases stem from our different evolutionary histories at least as much as siding with our tribes. As interesting as reading Stanovich’s book is, claiming that liberals and conservatives show now fundamental differences would be doing a disservice to science and humanity. It is better to investigate those differences and then find compromises that don’t make both sides try to kill each other. Stanovich did, however, convince me not to support higher taxes on petrol. So far I have always considered it a necessary measure to protect the environment. Stanovich says that liberals like me should think twice because it would hurt poorer people and hardly affect the behaviour of richer people. Not necessarily an outcome liberals do intend.

Stanovich’s book does have important lessons to teach. In a world that gets increasingly polarized, we do have to rethink our positions more often. If we like it or not, we should listen to the other side, they are often better at spotting the flaws in our logic. Universities are doing a disservice to science and their own reputation if they ban researchers who find differences in cognition between men and women. The scientific method is trying to replicate empirical findings, not firing scientists for producing results that are considered politically incorrect.

I tried to trace the evolutionary history of our myside biases in my book:

Originally published at on October 26, 2021.