Certain people frequently claim that religious experiences are the result of hallucinations, epileptic seizures, or other mental phenomenon, as opposed to being genuine experiences of rela phenomena. I don’t think this is true. To tackle the claim I’ll first look at one popular presentation of the claim, in Richard Dawkin’s book The God Delusion, in the section beginning on page 87.
To begin with, Dawkins titles the section “The Argument from Relgious ‘Experience’”, yet in the second paragraph he limits himself only to people seeing and hearing God (or some object of religious devotion). If we instead consult an expert, such as William James in The Varieties of Religious Experience, we would learn that only a small percentage of religious experiences involve visions or locutions (hearing a spoken message). Hence Dawkins is already off on the wrong foot, since his discussion ignores the majority of religious experience.
Dawkins then goes on to say that personal experiences are not convincing to anyone who hasn’t had one or to “anyone knowledgable about psychology”. Such an unsupported declaration that every knowledgable person agrees with Dawkins is unconvincing to me because it’s not true.
Next come a couple of paragraphs declaring that people who have religious experiences are insane. Dawkins compares them to “individuals in asylums”, then offers a quote from Sam Harris saying that religious people should be called ‘psychotic’. (In typical fashion Harris then backtracks and says “religious people are not generally mad”.) Once again, let’s turn to an expert, in this case Abraham Maslow, one of the most influential psychologists of all times. In his book Religion, Values, and Peak Experiences, Maslow rejects the notion that religious experiences are a sign of mental illness, instead describing them as “perfectly natural” and “healthy”, and even states that those with “robust mental health” are the most likely to have religious experiences. Hence the truth about this issue is the precise opposite of what Dawkins and Harris want us to think that it is.
Next Dawkins says, “The human brain runs first-class simulation software.” Actually the human brain runs no software of any kind, because software only runs on computers.
After that comes three pages dedicated to showing that optical illusions exist. (Not a subject that was in question, as far as I know.) Missing is any positive evidence for the claim that religious experiences are actually “hallucination or vivid dreaming”. Now let’s look at the evidence.
Neuroscientist Mari Beauregard has done extensive study and research on the topic of religious experiences. In his book The Spiritual Brain He rejects the claim that religious experiences are hallucinations because religious experiences are not similar to hallucinations. Specifically: (1) The typical religious experiences lasts much longer than the typical hallucination. (2) Typically the subject has a much clearer and more detailed memory of a religious experience than of a hallucination. (3) Religious experiences don’t generally occur in the same circumstances that hallucinations occur in.
Beauregard and Vincent Paquette did a study on Carmelite nuns, taking MRI scans of them while they were experiencing union with god. They found that:
In his book Beauregard points out that this MRI result contrasts sharply with the MRI result for a person who is hallucination. During a hallucination, mental activation is much more limited, and most of the areas on the list above do not light up. Hence the religious experiences of the Carmelite nuns are not hallucinations.
This is in agreement with a great deal of research from other sources. For example, dozens of scientists and doctors have examined the six visionaries from the Bosnian town of Medjugorje, who have been having visions of the Virgin Mary since the early 80’s. They have performed a battery of every conceivable test on the visionaries, and all the tests have confirmed that the visions are genuine, not a fake or a hallucination. Summary here:
http://www.medjugorje.org/science.htm
Perhaps most notable are the results from the electroencephalograph (EEG), which measure cycles of electric activity in the brain. A normal human brain has 10 alpha (receptive) cycles per 20 beta (reactive) cycles. During a daytime hallucination, alpha cycles would decrease and beta cycles would increase. For the Medjugorje visionaries, the opposite happens, proving that they are receiving visions from an outside source rather than from inside their own heads.
To conclude, religious visions and other experiences are not hallucinations.