You’re Not As Rational As You Think: Political Philosophy and the Neuroscience of Irrationality

Cognitive scientists have known for decades that humans are inherently irrational when it comes to making economic decisions. This may seem obvious to a good poker player, who will likely utilize mathematical probability to make economic decisions during a poker game, but to most people the fact that they have systematic economic biases might come as a surprise.

What might be even more unsettling is the fact that we are also prone to systematic irrationality when making political decisions.

One neuroimaging study, conducted during the 2004 U.S. presidential election, looked at how partisan voters process contradictory information about their party’s candidates. For example, subjects might read a quote by John Kerry espousing his support for economic sanctions instead of war in Iraq, and then in the next slide read a quote saying he unequivocally supports Bush’s decision to invade. As you might expect, Democratic subjects could recognize the contradictions in quotes by Bush and politically neutral celebrities, but found ways of rationalizing away Kerry’s inconsistencies. Republican subjects showed the opposite trend: They recognized inconsistencies in quotes by Kerry and by politically neutral celebrities, but not in quotes by Bush. This isn’t surprising, but what’s worth noting is that while subjects reasoned away their own candidate’s contradictions, their brains didn’t show any significant increase of activity in brain regions previously associated with “cold” reasoning. Instead, the researchers saw greater activation in brain regions associated with emotional processing.

John Kerry

The takeaway: Both liberals and conservatives fit new information into pre-existing, emotionally regulated cognitive schemas, regardless of whether or not doing so is logical. People might explain to you why their decisions are rational – they might even think that they arrived at their decisions through reason alone – but in fact they’re simply justifying “gut” emotional reactions. This is similar to what some cognitive scientists call retrospective construction, which is the illusion of having made a conscious choice after we have already unconsciously decided on a course of action.

Another study found that when doing a simple decision-making task that involved some risk, Republicans and Democrats showed significantly different activation levels in brain areas associated with emotional processing. Specifically, Republicans tended to more strongly recruit the right amygdala and Democrats tended to more strongly recruit the left insula. While you could come up with some story about what this means for the difference in how conservatives and liberals emotionally process information, the more interesting finding is that differential activation of the amygdala and insular cortex is a better predictor for partisanship than any other measure yet proposed – it’s far more accurate (82.9% accuracy) than guessing your affiliation based on your parents’ partisanship (69.5% accuracy). The problem this finding raises is this: How certain can you be that you have arrived at your political beliefs rationally when a neuroscientist can accurately predict those beliefs just by looking at brain regions involved in emotional processing?

What does this mean for political philosophy? Plato realized millennia ago that humans are inherently irrational. That’s why, in his Republic, he proposed that we should place all political power in the hands of trained philosophers, who are ostensibly more capable of “cold,” detached reasoning than the common person. He called these leaders philosopher-kings. But philosophers are also capable of bad reasoning – Plato himself lived long before people in the West started to seriously question the ethics of slavery or the subjugation of women. Placing all political power in the hands of one of his philosopher-kings, who would have likely acted in line with the moral ethos of the time, would have led to an immoral totalitarian state by today’s standards.


But we can sympathize with Plato’s concern over an unenlightened democracy: The citizens of Athens, the birthplace of democracy, voted to execute his mentor Socrates for corrupting the youth of the city. Perhaps Plato thought that if philosophers were in power, or if Athens had leaders who were capable of really rational thinking, then they would have recognized the service Socrates was providing by compelling other Athenians to critically examine their lives.

That same concern remains with us today: We value democracy, but if voters are uninformed and don’t think critically, then how are they to be trusted to make rational political decisions?

We have something that the ancient Athenians lacked, and that is near universal access to information. If ever a question about some fact arises, most people in the West are at most minutes away from the best answer we have. The problem is that near universal access to cold facts doesn’t seem to have made people better at cold reasoning. As we have seen, even when faced with clearly contradictory information, we can fit that information into pre-existing cognitive schemas. If we are to avoid voting for the wrong cause, as the Athenians did when they executed Socrates, then we must become more rational thinkers. But how can we get everyone to think more rationally?

The solution, I think, is near universal education in philosophy. If democracy is to make us all kings, then let us be philosopher-kings. Philosophers are by no means immune to the biases that lead to irrational decision-making, but training in philosophy makes you far more aware of your own biases, if only because other philosophers will pick apart every assumption and contradiction in your beliefs. And if it is difficult for someone to hold on to an irrational belief in a philosophy seminar, just imagine how hard it would be to perpetuate poor thinking in a society in which everyone is a philosopher-king.


2 thoughts on “You’re Not As Rational As You Think: Political Philosophy and the Neuroscience of Irrationality

  1. Let’s say I have a glass of wine. Studies show this reduces inhibitions. If I know that having wine reduces inhibitions, I will add an extra check to my actions to see if they are reasonable. Some actions, like motor reflexes, will not be subject to the check. Surely my deliberative decisions will be subject to the check. This means that I will become more reasonable and less impaired because I know that the glass of wine biases my judgment. Doesn’t your argument work the same way? You describe a process for increasing / establishing rationality in the face of bias. (I know you say the brain scans show activity in the emotional region of the brain but emotions are evidence that is useful for reasoning. You did not show that the brain completely loses rational function, so I am not inclined to take this line as a response.)

  2. As I understand it, you’re saying that becoming aware of the fact that we tend to process information emotionally rather than rationally makes our political decision-making process more rational. And this is possible because we are not completely irrational. Did I get that right? I’d agree – we’re not not completely irrational. After all, we do try to use reason to justify our gut decisions. And from personal experience, at least, I can say that becoming aware of my own biases has made me less quick to jump to conclusions and has made me more open to others’ criticisms of my own logic.

    It’d be interesting to conduct a study that tests whether reading about your own biases makes you reason through problems more carefully, or whether it makes you consider contradictory information more rationally. You could also check to see whether reading about your own biases makes your brain activity look any different when you are subsequently confronted with potentially contradictory information. There have been similar studies that have examined whether reading that free will doesn’t exist affects your ethical behavior.

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