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What Actually Is a Belief? And Why Is It So Hard to Change?

Beliefs evolved as energy-saving shortcuts. Restructuring them is costly.

“For some of our most important beliefs, we have no evidence at all, except that people we love and trust hold these beliefs. Considering how little we know, the confidence we have in our beliefs is preposterous—and it is also essential.”

2002 Nobel Laureate Daniel Kahneman1

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Source: Source: Alain Lacroix/Dreamstime

Beliefs are a slippery concept. What actually are they? Philosophy has long struggled to define them.2 In this post-truth and ideologically polarized world, we need a better understanding of beliefs. As a psychiatrist, my job frequently involves identifying distorted beliefs, understanding how they formed, and helping people to learn to be more skeptical of their own beliefs.

Let’s consider a helpful evolutionary framework for making more coherent sense of what beliefs really are, and why mistaken beliefs can sometimes be so hard to change. Then we’ll talk about how to gain a more accurate grasp of reality, and how, ultimately, to advance society.

Beliefs as energy-saving shortcuts in modeling and predicting the environment3

Beliefs are our brain’s way of making sense of and navigating our complex world. They are mental representations of the ways our brains expect things in our environment to behave, and how things should be related to each other—the patterns our brain expects the world to conform to. Beliefs are templates for efficient learning and are often essential for survival.

The brain is an energy-expensive organ, so it had to evolve energy-conserving efficiencies. As a prediction machine, it must take shortcuts for pattern recognition as it processes the vast amounts of information received from the environment by its sense organ outgrowths. Beliefs allow the brain to distill complex information, enabling it to quickly categorize and evaluate information and to jump to conclusions. For example, beliefs are often concerned with understanding the causes of things: If ‘b’ closely followed ‘a’, then ‘a’ might be assumed to have been the cause of ‘b’.

These shortcuts to interpreting and predicting our world often involve connecting dots and filling in gaps, making extrapolations and assumptions based on incomplete information and based on similarity to previously recognized patterns. In jumping to conclusions, our brains have a preference for familiar conclusions over unfamiliar ones. Thus, our brains are prone to error, sometimes seeing patterns where there are none. This may or may not be subsequently identified and corrected by error-detection mechanisms. It’s a trade-off between efficiency and accuracy.

In its need for economy and efficiency of energy consumption, the default tendency of the brain is to fit new information into its existing framework for understanding the world, rather than repeatedly reconstructing that framework from scratch.

Seeing is believing

It seems likely that the processes in the brain involved in abstract belief formation evolved from simpler processes involved in interpreting sensory perception.

Since we experience the external world entirely through our senses, we find it hard to accept that these perceptions are sometimes subjectively distorted and that they are not necessarily reliable experiences of objective reality. People tend to trust their physical senses and to believe their perceptions even when they are hallucinating and no matter how bizarre their perceptual distortions. People will layer explanations on top of their perception of reality to explain away contradictions.

We give our subjective experience too much credence, and so too our beliefs. We will more readily explain away evidence that contradicts our cherished belief by expanding and elaborating that belief with additional layers of distorted explanation, rather than abandoning it or fundamentally restructuring it.

Homeostasis — maintaining stability

Primitive nervous systems evolved in simple organisms in part to serve the function of homeostasis—a dynamic physiological state of equilibrium or stability, a steady state of internal conditions. Homeostasis is structured around a natural resistance to change, following the same principle as a thermostat.

The lower, primitive parts of our human brains maintain homeostasis of breathing, heart rate, blood pressure, temperature, energy balance (via appetite) and a variety of endocrine processes. So too, beliefs preserve a kind of cognitive homeostasis—a stable, familiar approach to processing information about our world.

We should expect that the homeostatic function that defined primitive brains would likely have been preserved as an organizing principle in the evolution of more complex brains. Certainly, complex brains are geared toward reacting, learning and adapting, but just like primitive brain functions, these adaptations are ultimately in the service of maintaining homeostasis in an ever-changing environment.

Radically restructuring our belief system and creating a new worldview engages parts of the brain involved in higher reasoning processes and computation, and is consequently more effortful, time- and energy-consuming. The brain often cannot afford such an investment. This would explain why, when we experience cognitive dissonance, it is easier to resolve this discomfort by doubling down on our existing belief system—ignoring or explaining away the challenging, contradictory information.

A consistent sense of self, and personal investment in one’s beliefs

Another important factor accounting for resistance to changing our beliefs is the way our beliefs are so often intertwined with how we define ourselves as people—our self-concept. Indeed, beliefs are associated with a part of the brain integrally involved in self-representation—the ventromedial prefrontal cortex.4 We want to feel that we are consistent, with our behavior aligning with our beliefs. We constantly try to rationalize our own actions and beliefs, and try to preserve a consistent self-image. It’s embarrassing and quite often costly in a variety of ways to admit that we are fundamentally wrong.

In many cases, people have a lot invested personally in their belief system. They may have staked their reputation on a particular belief. Not infrequently, people structure their whole lives around a belief. And this investment may go far beyond a sense of self, extending to large material and financial investments or a life’s career. A change of belief for such a person would obviously involve a monumental upheaval and may entail intolerable personal losses.

No wonder it’s so hard to change our cherished and entrenched beliefs.

The social dimension of belief

A lot of our belief framework is learned at an early age from parents and other adult authority figures. Many human beliefs are the cumulative products of millennia of human culture. Children are strongly predisposed to believe their parents, and, as adults, we are inclined to believe authorities.

It's not surprising that our brains have evolved to more readily believe things told to us than to be skeptical. This makes evolutionary sense as a strategy for efficient learning from parents, and as a social, tribal species it promotes group cohesion.

People can be swayed by persuasive individuals or compelling ideas to override and reject their previously received authority. Sometimes, this is rational. But sometimes, it is not—people are susceptible to influence by charismatic ideologues and by social movements. Especially when these offer new attachments and new self-identities imbued with more powerful affiliation, validation, esteem and sense of purpose than the individual previously had in their life.

Science and the excitement of proving ourselves wrong

Science values the changing of minds through disproving previously held beliefs and challenging received authority with new evidence. This is in sharp contrast to faith (not just religious faith). Faith is far more natural and intuitive to the human brain than is science. Science requires training. It is a disciplined method that tries to systematically overcome or bypass our intuitions and cognitive biases and follow the evidence regardless of our prior beliefs, expectations, preferences or personal investment.

The increasing application of the scientific method in the last four centuries ushered in unprecedented, accelerating progress in humanity’s quest to understand the nature of reality and vast improvements in quality of life. Discovering just how mistaken we collectively were about so many things has been the key to sensational societal progress.5

Imagine if each of us as individuals could cultivate a scientific attitude of rigorous critical thinking and curiosity in our personal lives, and could experience an exhilarated feeling of discovery whenever we find we have been wrong about something important. Perhaps it’s time to stop talking admiringly about faith and belief as if these were virtues.

Faith is based on belief without evidence, whereas science is based on evidence without belief.


1. Daniel Kahneman, Thinking, Fast and Slow, New York: Farrar, Straus and Giroux, 2011, p. 209.

2. See for example Schwitzgebel, Eric, "Belief", The Stanford Encyclopedia of Philosophy (Summer 2015 Edition), Edward N. Zalta (ed.),

3. Parts of this article are taken from: Ralph Lewis, Finding Purpose in a Godless World: Why We Care Even If The Universe Doesn’t (Amherst, NY: Prometheus Books, 2018). The book is a deeper dive into questions of purpose, meaning and morality in a random, purposeless, godless universe. Among other topics, the book discusses in more depth the psychology of belief, developing an understanding motivated by respectful curiosity as to how and why humans are predisposed to religious belief. The book provides an accessible understanding of the counter-intuitive scientific insights that have led today’s scientists to confidently state that the universe, life and human consciousness are the wondrous products of fundamentally random, unguided processes rather than the creation of an intelligent designer.

See this YouTube video link for an engaging Power Point presentation in which Dr. Lewis explains how a family health crisis focused him on coming to terms with the outsized role of randomness in life, and to wrestle with the question of whether the scientific worldview of a fundamentally random universe is nihilistic. He summarizes how science has come to view the universe and absolutely everything in it as the product of entirely spontaneous, unguided processes, and why this is actually a highly motivating realization for humankind. Or see this link for a very brief video providing a synopsis of the book.


4. Harris, S., et al., The neural correlates of religious and nonreligious belief. PLoS One, 2009. 4(10): p. e0007272; Harris, S., S.A. Sheth, and M.S. Cohen, Functional neuroimaging of belief, disbelief, and uncertainty. Ann Neurol, 2008. 63(2): p. 141-7. The ventromedial prefrontal cortex is also involved in emotional associations, reward, and goal-driven behavior.

5. Democracy also loosely employs the scientific method of conjecture and criticism. Each election platform is an hypothesis, each elected government an experiment, subjected to the peer review process of a free press and the next election. The combination of science and democracy has been the key to human progress. To be sure, this progress has not been smooth or without calamitous derailments in modern history. But the overall trend over time has been definitively and spectacularly positive, and it is indisputably the most successful system humans have invented to date.

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