Would You Know if You Held a Weird Belief?

The continuum of irrationality and delusion—and why religion is not a delusion.

Posted Aug 22, 2019

 Dreamstime | Angela Ostafichuk
Source: Dreamstime | Angela Ostafichuk

Would you know if you’re delusional?

Do you have any false beliefs, strongly held in the face of refuting evidence? Of course not, from your own point of view. Me neither. Have other people told you that some of your beliefs are false, and have they tried to present you with refuting evidence from their point of view? Sure. Me too. Many times.

Who’s the arbiter of truth and reality? Parents? Teachers? Professional experts in each field? Government authorities? Religious authorities? Scientists?

What is a delusion?1

Delusions are defined as “fixed, false beliefs, strongly held and immutable in the face of refuting evidence, that are not consonant with the person’s educational, social, and cultural background.”2

Delusions and irrational beliefs are on a continuum.

While psychotic delusions can be extremely bizarre and the person suffering from psychosis may be severely out of touch with reality and very impaired in their functioning, many delusions seen in mentally ill patients are not necessarily blatant, and are practically indistinguishable from the plethora of irrational unscientific beliefs held by a large swath of the mentally healthy population. There is not a definitive line separating delusions from regular irrational beliefs that are based on faulty evidence.

Rather, in determining whether a belief is delusional, psychiatrists routinely consider other factors (in addition to whether the belief is shared by other people in that individual’s cultural or social group). These factors may include whether the belief is causing significant distress and impairment of the person’s functioning, whether it is out of character for that person, and whether it is accompanied by other tell-tale symptoms of psychosis, such as marked sleep disturbance.

The wide prevalence of strange beliefs in the mentally healthy general population

Irrational beliefs based on distorted reality can be tenacious and impervious to contradictory evidence. This includes both individual, idiosyncratic beliefs and those shared by large groups of people. There is no shortage of examples of widely held irrational beliefs shared by many mentally healthy people, on topics spanning astrology, alien abduction, ESP/telepathy, homeopathy, vaccines causing autism, implausible conspiracy theories, and more.

Why and how are so many thoroughly invalidated beliefs confidently shared by such large numbers of mentally healthy people? More than mere credulity and suggestibility are at play, but a lack of critical thinking skills is certainly a part of it.

Science is the antidote (but science is hard)

The scientific method is a rigorous methodology that has gradually developed over time. It helps us arrive at a more objective, accurate understanding of reality, controlling for our subjectivity, cognitive biases, assumptions, and potentially misleading intuitions (intuition is valuable for generating hypotheses but is an obstacle when testing them). Scientific progress relies heavily on the highly critical scrutiny of the peer review process, and independent replication. Scientists are highly motivated to disprove each others' hypotheses.

The scientific method is based more on disproving hypotheses than on proving them.


A crucial element of scientific rigor is that scientific hypotheses must be structured in such a way as to expose themselves to the possibility of being proven wrong. This is referred to as falsifiability.

Delusions are usually structured as unfalsifiable beliefs: the delusional person explains away evidence that contradicts the delusion by expanding and elaborating the delusion with additional layers of explanation. For example, the doctor who points out the evidence for the impossibility of the paranoid conspiracy against the patient must be one of the conspirators. Delusions typically cannot be reasoned away.

A patient of mine3 who was psychiatrically hospitalized in an agitated, paranoid state was convinced that a criminal gang whom she believed had been staking out her house planned to murder her family that very day. I asked her if the appearance of her family in an anticipated visit to the hospital that evening and their own attempts to reassure her would prompt her to consider that she might be mistaken. But no, she insisted, that would actually be even stronger proof that they were in immediate danger, as they had clearly been duped and lulled by sedative drugs slipped into the house’s drinking water, and would be led away from the hospital to be killed. She had thus added another layer of delusion to explain away the contradictory evidence.

Non-psychotic irrational beliefs are the same. An invariable characteristic of New Age spiritual beliefs, pseudo-scientific theories, fringe conspiracy theories, and other such beliefs is that they are unfalsifiable.

To ensure that your own beliefs do not have that characteristic, ask yourself this simple question: What would it take for you to change your mind?

There exists a green swan

As explained by the twentieth-century philosopher of science Karl Popper, an example of a falsifiable hypothesis is “all swans are white.” We can test this hypothesis by going looking for swans. If we ever find even a single black swan, we will have definitively disproved (falsified) our hypothesis. The hypothesis “all swans are white” is thus structured in a scientifically valid way.

In contrast, a hypothesis that “there exists a green swan” is unfalsifiable: it cannot be undermined by evidence because it is structured in such a way that it can never be definitively disproved, no matter how long we keep searching without ever finding a green swan. It could always be argued that we have just not looked hard enough, or that green swans have some characteristic that makes them difficult to discover.

What about religious beliefs?

Religious beliefs are almost invariably structured as unfalsifiable hypotheses. Belief in God is very much a green swan hypothesis.

Science and religion flatly contradict each other: The problem is that all the scientific evidence shows us that the universe and everything in it, including all the complex life on this planet and our conscious selves, is entirely the product of spontaneous unguided processes. As I have argued before, the scientific view does not require an Intelligent Designer and is utterly incompatible with one.

So is belief in God a delusion?

No, belief in God is not clinically delusional, from my professional point of view as a psychiatrist, or that of most of my colleagues, including the atheists among us.

In The God Delusion, Richard Dawkins's bestselling polemic against religion, the title of the book is meant to suggest that all belief in gods is delusional.4 While this may be an effective rhetorical device, it would be a clinically invalid use of the term “delusion” in a psychiatric clinic. Remember that the definition of delusions states that they “are not consonant with the person’s educational, social, and cultural background."

A patient's religious beliefs are deemed to be abnormal only if they represent a fairly dramatic and abrupt out-of-character change for that individual and are very incongruent with the sociocultural group with which the individual affiliates. For example, a young Jewish man was brought to me by his secular parents because he had recently become fervently devout, was constantly preaching to his family, and had left his girlfriend and stopped seeing his friends. He talked about how he had heard the voice of God the previous month. Since then, he had barely slept and was up at night reading the Torah. He wanted to drop out of engineering school to pursue a mission of returning all the non-believing Jews of Toronto to the ways of the Torah.

The fallibility of subjective perception and intuition

The very strongest forms of religious faith have usually been cemented by subjective experience—some kind of first-hand experience of God's presence or the miraculous. It's natural for people to trust their own subjective perceptions first and foremost, and these are often powerfully reinforced by strong emotions. But subjective experience and intuition are notoriously the most unreliable forms of evidence—people give them far too much credence. It is precisely because of the distorting power of subjectivity and intuition that the scientific method is so necessary.

Layering beliefs with new explanations rather than abandoning them in the face of contradictory evidence

As we have seen, a common characteristic of delusions, paranormal and anti-science beliefs, and indeed (by definition) religious faith, is the imperviousness of the belief to contradictory evidence. Because the core belief is held with such motivated conviction and its invalidation is not an option, when faced with refuting evidence the holder of the belief must create additional layers of explanations to maintain the belief. People do this instead of cutting through and replacing the contradicted belief with a simpler, more elegant model that fits the data more tightly.

How can we recognize a rational belief (a good explanation)?

Oxford physicist David Deutsch defines a “good explanation” as one that is difficult to (arbitrarily) vary.5 A good explanation is a model that fits the data/evidence tightly and elegantly without resorting to caveats or extra layers of explanations. For example, Copernicus’s heliocentric model of the solar system (sun at the center; Earth revolving around the sun) was a better explanation than the Ptolemaic geocentric model (Earth at the center). Ptolemy's geocentric model was favored by the Church at the time because it put humans at the center of God's creation, not off to the side on one of many planets. But as anomalies were discovered in the planetary orbits, to make the geocentric model keep working required the addition of loops upon loops (epicycles) in those orbits. As Galileo ultimately showed with convincing evidence, Copernicus’s heliocentric model fit the data more elegantly, without all those arbitrary extra layers of explanation.


The above example, along with many others in the history of science, demonstrates that accepting a good explanation often involves abandoning cherished beliefs and discarding assumptions in which we are emotionally invested.

So, be skeptical, especially of your own beliefs, and particularly those beliefs that are incapable of being falsified by evidence. Note that we're talking here about the rigorous, disciplined skepticism of the scientific method, backed up by careful statistical analysis and all the self-correcting checks and balances of that methodology—not the pseudo-skepticism of conspiracy theorists.

And be prepared to sometimes mistrust your subjective experience and intuitions when the evidence points to a different conclusion. Don’t believe everything you think.


1. 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). 

2. Benjamin Sadock, et al., eds., Kaplan & Sadock’s Comprehensive Textbook of Psychiatry. 9th ed. (Philadelphia: Lippincott Williams & Wilkins, 2009), p. 1080.

3. Patient details have been altered to protect anonymity.

4. Richard Dawkins, The God Delusion (Boston: Houghton Mifflin, 2006).

5. David Deutsch, The Beginning of Infinity: Explanations That Transform the World (New York: Viking, 2011), pp. 24–25.