Rationality

Rationality is the ability to use reason and logic to make decisions and achieve goals. It involves basing beliefs and actions on clear, structured thinking, critical analysis, and systematic evaluation of available evidence. A rational person uses these tools to justify their decisions and behaviors, ensuring they are grounded in well-reasoned arguments and supported by strong evidence.

The Basic Idea

The average adult makes around 35,000 decisions each day.¹ From trivial choices like what to eat for breakfast to more significant choices about finances or relationships, life is one long stream of decisions. Even the act of choosing an opinion is a decision in itself. Many of these daily decisions produce inherently neutral consequences—whether you eat cereal or toast for breakfast won’t alter the course of your life. We make most of these mundane decisions automatically and efficiently without too much deliberate thought. However, some decisions significantly impact our lives, and this is where rationality comes into play.

Rationality, or the ability to respond to reason, involves actively reflecting on the possible consequences of your actions and deciding on a choice that brings you closer to your goals.² This includes reviewing what you already know, deliberately thinking about new information coming in, using this information to modify your existing beliefs, and applying this knowledge to future decisions.

Rationality is an admired and sought-after quality, but it is not always perfect. We don’t always use rational thought in the pursuit of objective truths. Rather, human reasoning is constantly clouded by emotions and personal motivations. We might use rationality simply to win an argument or persuade someone to make a decision that would benefit us, even if it’s not the best decision for everyone.

Even when rationality would lead to better personal outcomes, we still sometimes fail to make rational decisions. For instance, people who fear flying might take a long drive to avoid getting on an airplane, even though flying is much safer than driving.³
Our decisions are strongly influenced by biases, or unconscious mental processes that happen quickly and automatically.² We revert to these processes when our brains are limited by time, data, or computational power, relying on rules of thumb to help us make decisions efficiently. It’s important to note that these deviations from rationality are not always bad. Relying on mental shortcuts can often drive us towards adaptive decisions where full rationality would be impossible. These biases also infuse our decisions with emotion, allowing us to consider empathy, compassion, and the perspectives and values of other people—ensuring our decisions are not so rational that they are robotic and heartless.

Epistemology: The philosophical study of knowledge. Epistemology is concerned with the nature and scope of knowledge and related issues, including the rationality of belief. 

Theoretical Rationality: A type of rationality dealing with the rationality of beliefs.⁴ Theoretical rationality is rooted in cognitive processes rather than action. It involves drawing conclusions and forming opinions based on available arguments and assumptions. For example, it is theoretically rational to believe that it might rain when you see dark clouds approaching on the horizon.

Practical Rationality: A type of rationality concerned with the rationality of actions or decisions.⁴ Practical rationality refers to the rationality of our actions in terms of how they might bring about a certain goal. For example, it would be practically rational to develop a budget if you want to save money for an upcoming vacation.

Bounded Rationality: The idea that our rationality is always limited when we make decisions because we have incomplete information or limited cognitive resources. Faced with these limitations, rational people choose satisfactory solutions rather than optimal solutions. This idea suggests that we are not fully rational beings due to the natural limitations of our minds.

Cognitive Biases: Systematic errors in thinking that deviate from rationality. Cognitive biases result from the brain’s tendency to streamline and simplify information processing, allowing us to make decisions unconsciously and automatically.
Homo Economicus: Latin for “economic man,” this term describes a hypothetical figure who represents the concept of unconditional rationality. This caricature is what traditional economic models were based on—although today, we recognize that no actual person acts in a vacuum without cultural, emotional, physical, or mental influences.

The roots of rationality can be traced back to ancient Greece during a time when philosophers were shifting focus from mythological narratives to logic and reason-based explanations for phenomena.⁵ This shift marked the beginning of the systematic study of philosophy and science through an emphasis on classifying and categorizing knowledge.

Aristotle made some of the most significant contributions to these early discussions of logic and reason. He stated that humans are rational animals because we base our behaviors on thought and reason, arguing that rationality is the essence of what makes us human and sets us apart from other species. In these epistemological discussions, philosophers like Aristotle and Plato laid the groundwork for logical reasoning.

The concept of rationality evolved during the 17th and 18th centuries of the Enlightenment—a period aptly called the “Age of Reason.” Up until this period, rationality was largely about certainty or the practice of basing beliefs and actions on concrete truths. During the Enlightenment, the notion of rationality shifted towards probabilistic reasoning—making the best decisions with incomplete information. The concept of rationality was now more about responding reasonably to uncertainty and making decisions based on what was likely true rather than what was definitely true.

This was also a time when scholars began recognizing the limits of human rationality and exploring the potential for bias in thinking. In the 20th century and beyond, developments in psychology and cognitive science revealed many ways in which decision-making deviates from rationality. Researchers are still exploring these biases today.

Understanding Cognitive Biases

Research and discussions on rationality have contributed to our understanding of how people make decisions. This has led to the development of many psychological theories attempting to explain how reasoning occurs and what processes get in the way of rational thought. For example, the study of cognitive biases is based on the concept of irrationality and the underlying psychological processes that are responsible for this. 

These biases influence how we evaluate the risks and rewards of our choices, like whether or not it's rational to purchase insurance, gamble, or go skydiving. For example, we are naturally biased towards choices that help us get more of a good thing or less of a bad thing. We also tend to prefer choices that are easier to envision (availability heuristic) or align with our existing beliefs (confirmation bias). 

These deviations from rationality are often seen as mistakes or misbehaviors.⁶ Sometimes, we attribute a lack of rationality to a lack of thought entirely, claiming we were absentminded or “just not thinking” when we made an irrational decision in the past.

However, it’s important to point out that irrationality is not a lack of thought, but our thinking being skewed by cognitive biases. This can even be a good thing! Biased thinking helps us make tens of thousands of daily decisions without draining our cognitive resources and enables us to act quickly in emergencies.

Behavioral Economics

Studying human rationality is also important for understanding why people make irrational economic decisions. Why do some people spend money on luxury cars instead of saving for retirement? Insights from irrational behaviors like these can help policymakers account for cognitive biases and implement strategies to help people make better choices. 

For instance, nudge strategies are behavior interventions that guide people toward better decisions without limiting their freedom of choice. Research in this area has significantly expanded our ability to maximize productivity and problem-solve, contributing to innovation and economic growth but also advancements in healthcare and environmental sustainability.⁷

Development of Artificial Intelligence
Our understanding of rationality can also contribute to the development of artificial intelligence (AI). One of the goals of creating AI models is to create rational decision makers.⁸ The notion of rationality plays an important role in determining how we can simulate human reasoning by building AI systems that make good decisions even when they lack certain information or resources—much like our own bounded rationality. At the same time, understanding the thought processes behind irrational human behavior can help us mitigate similar issues in AI programs, ensuring AI decisions are truly aligned with our goals.

Are Humans Rational?

One of the largest debates surrounding rationality is whether humans are fundamentally rational beings or if our behavior is mostly driven by irrational biases. There is no clear answer to this question—scholars have been debating what it means to be rational for millennia! 

Traditional economic theories assume that humans always make rational decisions by carefully evaluating the costs and benefits of each choice and selecting the option that leads to optimal outcomes. For example, someone might choose to buy a certain car because it provides the best mileage for the price. However, behavioral economics demonstrates that our decisions are often skewed by emotion or bias. Think of how many people buy expensive gas-guzzling cars even though there are more economical options available.

However, some argue that simply making a decision because you believe it to be the best decision is a form of rationality. Max Weber, one of the founders of sociology, argued that humans are always capable of subjective rational action.4 Weber suggested that rationality is the basic human capacity to base actions on our values and beliefs, even if our actions appear irrational from an objective standpoint.

Rationality and Emotion

Emotions present another problem for rationality. Are emotions part of rationality or is true rationality completely devoid of emotion? Research suggests that emotions can be useful in making decisions — emotions like fear have clear adaptive benefits.⁹ At the same time, emotions can interfere with our ability to make rational decisions and lead us toward choices that don’t align with our goals. For example, a person might avoid making a career change due to fear of failure, even if this change aligns with their professional goals.

Still, many economists, psychologists, and philosophers agree that emotions and rationality can coexist. Emotions can provide valuable insight into problems when facing complex information and often contribute to prosocial behavior. For example, you might choose to help out a friend in need by lending them some money, even if this is not the most rational decision in light of your economic goals.

Emotions play a key role in ensuring our decisions are not overly rational. Rational decision-making can and should incorporate emotions and ethical considerations, ensuring our choices are not only aligned with our own goals but also in the interest of the greater good.

The story of Stanislav Petrov, known as “the man who saved the world,” is a compelling case study of rationality and the value of employing reasoning when making decisions under pressure.¹⁰

Petrov was a lieutenant colonel in the Soviet Air Defense Forces during one of the most tense periods of the Cold War. He was responsible for monitoring the signals coming from Soviet surveillance satellites covering the United States. On September 26, 1983, the Soviet nuclear early warning system detected an incoming missile strike from the U.S., reporting that five missiles had been launched. If Petrov followed protocol and reported the attack, the Soviets would respond with nuclear retaliation, potentially leading to a global nuclear war. 

As you might have guessed, we managed to dodge this disastrous outcome. Petrov did a remarkable job of thinking rationally in the face of immense pressure, carefully analyzing the situation and employing logic and reasoning to conclude that the warning was likely a false alarm. He reasoned that if the U.S. was actually attacking, it would have launched more than a handful of missiles. He also considered the reliability of the alert system, which was fairly new and had been rushed into service. In the end, Petrov determined the alert was a false alarm and did not report the missile launch.

Petrov took a rational approach to this decision by assessing the reliability of information coming in, considering the likelihood of different outcomes, and using reasoning to make a decision when information was lacking. Had he blindly followed protocol or made a decision based on impulse and emotion, he might have passed on the alert and we might not be here today. Thank you, rationality!

Rationalism

Rationalism is an epistemological school of thought positing that opinions and actions should be based on reason rather than religion or emotion. This view emerged during the Enlightenment, when concepts of rationality, logic, and empiricism were taking center stage. See this article for more on rationalism and where it started.

Does Emotion Affect Our Ability To Make Rational Decisions?

We touched on this topic in the above article, but there’s a lot more to the relationship between emotion and rationality. This article explores whether inhibiting emotions can help people make more rational decisions and details some of the neuroscience involved in studying this topic.

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10. Jones, S. (n.d.). Stanislav Petrov, the Man who Saved the World. Historic Flix. Retrieved July 9, 2024, from https://historicflix.com/stanislav-petrov-the-man-who-saved-the-world/