Rational Irrationality: Believing What We Want to Believe

The theory of rational irrationality shows how absurd ideas and decisions obey a logic that contradicts the basic principles of reason.
Rational Irrationality: Believing What We Want to Believe
Gema Sánchez Cuevas

Written and verified by the psychologist Gema Sánchez Cuevas.

Last update: 01 November, 2022

Rational irrationality is a concept proposed by the economist, Bryan Caplan, to describe a concept that various psychological approaches have attempted to address. It’s the fact that, as human beings, we behave with high doses of irrationality. In other words, to a great extent, we’re not guided by reason.

The concept of rational irrationality suggested by Caplan claims that beliefs and behaviors are often seen as irrational, but deep down they do have a logic. He suggests that they don’t obey obvious reason, but they do obey other forms of rationality.

Ultimately, rational irrationality claims that we turn our beliefs into arguments, often against a great deal of evidence to the contrary. It tends to occur in the field of religion and politics. However, there are also episodes in the history of science to which this concept can also be applied. Let’s take a closer look.

The problem with people is not that they don’t know, but that they know so much that ain’t so.” 

-Josh Billings-

Concentrated woman at the computer thinking

Rational irrationality

Bryan Caplan argues that there are two types of rationality: epistemic and instrumental. The first is rational with a capital R: our beliefs try to conform to testable ‘truth’. We avoid untruths and keep open minds toward new evidence. If the evidence contradicts our beliefs, we abandon them.

The second is instrumental rationality. In this case, in a colloquial way, we believe what suits us to be true. This isn’t hypocrisy or opportunism. Quite simply, we naturally choose to believe what we want to be true because it makes it easier for us to achieve our goals.

Bryan Caplan points out that rational irrationality is configured when tension arises. For example, epistemic reason contradicts instrumental reason and vice versa. This is a circumstance that not only occurs individually but also collectively. Caplan indicates that it’s more likely to occur when there are two circumstances:

  • There are more preferences than beliefs. This happens when something is extremely attractive and pushes existing beliefs into the background. For example, a genre of lousy music becomes popular. It starts to be seen as good because it’s so popular.
  • Holding an erroneous belief doesn’t imply a high cost. In other words, it’s possible to continue in error, without negative consequences.

Irrationality isn’t doublethink

Rational irrationality is often confused with doublethink, where the individual deliberately decides to believe something they believe to be false. On the contrary, this theory postulates that people relax their intellectual standards when the costs of possessing erroneous beliefs are low.

Preferences and beliefs

Why do preferences end up taking the place of rational beliefs? The rational irrationality approach maintains that it occurs when new beliefs appear that are so attractive that they relax people’s criteria of truth.

As a rule, it happens when one or more of the following conditions are present:

  • Self-interest bias. Believing in something personally benefits those who believe in it, or the group with which they identify. For example, if you’re a vegan, you’ll tend to believe what other vegans say, even if it’s far-fetched.
  • Self-image beliefs. There’s a tendency for you to consider more what reaffirms the image you have of yourself, or the one that you want to adopt and project. For instance, if you want to look brave, you’re more likely to believe everything that suggests you are, no matter how silly it may be.
  • Beliefs by social connection. You have a tendency to preserve the beliefs that allow you to stay as part of a group or access a group you want to join.
  • Coherence bias. You tend to believe in new ideas that fit in with your existing ones, even if there’s no evidence to support them.
many people talking

Believe what you want to believe…

The theory of rational irrationality states that you often believe what you want to believe, even if there’s evidence that it’s not true. It’s because you derive a certain benefit from this kind of unintentional self-deception. A certain interest satisfies you and that’s why you stick to your guns.

This has great implications, especially in the political arena. For example, many people choose unsuitable leaders but no one can explain why. The theory of rational irrationality accounts for the reasons why this phenomenon occurs.

Ultimately, from the collective point of view, the weight of attraction is worth more than that of ideas. That’s the reason why crazy beliefs are often imposed collectively. They offer something (a paradise, salvation, unique well-being, etc.). This becomes so attractive that reason is renounced.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Caplan, B. (2001). Rational ignorance versus rational irrationality. Kyklos, 54(1), 3-26.
  • Contreras Medina, F. R. (2006). Estudio crítico de la razón instrumental totalitaria en Adorno y Horkheimer. IC Revista Científica de Información y Comunicación, 3, 63-84.
  • Sánchez Montilla, J. A. (2021). Preferencias musicales y creencias adolescentes: el sesgo sexista y romántico. Andalucía educativa.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.