Brain Salad Surgery

A person "sees a tree." He is asked what caused him to see this. "Well, light from the tree coming to my eyes."

A neuro-phile says, "No, what caused you to have that experience was this brain state I detected." *

The neuro-phile is obviously confused: these are not competing explanations, but complementary explanations from different points of view.

If someone asks me, "Gene, why are you in England?" then "I came for a conference" and "This is where the jet landed" are not contradictory answers! They address the question from two different perspectives.


A person experiences strange fits. Doctors are puzzled as to what is occurring, but he is not: Aliens are beaming mind-control waves into his head, totally disrupting his brain patterns.

We may not believe him, but that will be because we doubt aliens are visiting the earth, or something like that. What would be absurd here is to point to his unusual brain scans and say, "See, it is just that your brain is all funny!"

Because that is exactly what he (and we) should expect to find if his explanation is correct! His come back will be, "Of course my brain is all funny! That is what I have been telling you, and it is the aliens that are doing it!"

NOTE: The point here is not that we should believe the person having fits: it is that it is nonsense to try to use his odd brain states as evidence against his explanation, since those brain states fit his explanation perfectly.


August Kekulé reports that, in a daydreaming state, he had a vision of a serpent eating its own tail, and that this enabled him to solve the mystery of the structure of benzene.

Kenneth von Skeptik scolds him: "You had no vision about benzene! Your brain was just in an altered state. Here: I can show you the brain scan."

Obviously again, Kenneth is talking nonsense: Kekulé was both in a state where his brain waves were altered, and where he had a vision. These explanations don't compete with each other: they are alternate ways of describing the same event.

(Imagine: you tell a friend you just took a family vacation, and he contradicts you by saying, "No, you and your kids' molecules were just traveling in certain trajectories through space!")


Hildegard of Bingen has visions. They seem to her to be from God, but she is uncertain. So she corresponds with Bernard of Clairvaux, Pope Eugene III (now you see why I like her!), and others. After examining her claims with some skepticism -- the Church heirarchy was really, really not enthusiastic about people who went around claiming to be talking to God, since God might tell them to challenge the heirarchy: see, Luther, Martin or Bruno, Giordano for illustrations on this point -- these people admitted that, yes, these seemed to them like genuine visions. For one, she did not merely "see lights," but she received theological messages, and those messages seemed sound.

Following these visions, Hildegard launches a career of writing theology, medicine, theater, music, letters, and of traveling about preaching, one that is simply extraordinary for anyone of anytime, let alone for a woman in the Middle Ages. Furthermore, in her medical writings, Hildegard describes migraines in some detail: people then knew quite well that migraines existed, and in particular, Hildegard was very familiar with them. What did not happen at the time was that all of these migraine sufferers claimed divine visions, and went on to become great polymaths, or that every nearby monk immediately put up every migraine victim for sainthood. In fact, I'd bet it is safe to say that 99.999% of migraine sufferers do not have experiences like Hildegard's.

Now, I don't think for a second that any of the above constitutes proof that Hildegard had visions sent by God! But, just as with the UFO believer in case 2, or Kekulé in case 3, what is ridiculous is to point to the fact that Hildegard might have been in some unusual brain state as contradicting the idea that her visions had a divine origin. If the creator of the universe is projecting a vision straight into your head... well, don't you think that might put your brain in a rather unusual state?

* Let us leave aside the questions of if brain states can be said to "cause" experiences, and how they might do so, and just accept that there is some connection between the two, and use "cause" to describe it.


  1. If you knew what normally caused a particular unusual brain state and it was something other than god then it would not be ridiculous to point to the fact that Hildegard was in that brain state as contradicting the idea that her visions had a divine origin.

    1. "and it was something other than god"

      God is not a material cause amongst other material causes. ALL material causes are "something other than God," or looked at differently, none of them are.

      An analogy to your reasoning: if we know what conditions in the brain cause us to hear sounds, then we can point to that fact to contradict the idea that someone is trying to get our attention!

      The fact that there is a MATERIAL cause for some event has nothing whatsoever to do with whether some conscious entity intended to communicate with us through that event.

      If I give the material causes of your words showing up on this screen, does that "contradict" the fact you were trying to comment on my blog?!

    2. It would be perfectly consistent for me to think that a brain state that causes me to hear sounds would be present when someone is trying to verbally get my attention since that is a situation where I am indeed likely to be hearing sounds.

      But if I know that my brain state is caused by my friend calling me to get my attention, wouldn't that mean I was justified in thinking that this brain state was not actually caused by my cable box sending messages into my brain electronically ?

    3. You are in total confusion on this rob: You are unable to sort out the *efficient* cause of something from its *final* cause. Your friend trying to get your attention is NOT an efficient cause: it is a final cause. The efficient cause of the sound is sound waves reaching your ears.

      In the case of Hildegard, you claim that if we know the efficient cause of her visions was a migraine, then (somehow!) we know that this rules out the possibility that God was communicating to her.

      That is exactly analogous to: What caused those sounds I heard was sound waves (efficient cause), so that rules out the possibility that my friend was trying to communicate to me!

    4. "In the case of Hildegard, you claim that if we know the efficient cause of her visions was a migraine, then (somehow!) we know that this rules out the possibility that God was communicating to her."

      I don't claim that at all. God may indeed give people migraines as part of the vision transmission process.

      If however I knew that the French had developed a weapon that created unusual brain patterns , that gave people migraines and caused them to see visions, and that one of these weapons had been deployed round the corner from where Hildegard lived on the day of one of her visions then I would think this fairly good circumstantial evidence that this vision was not caused by god (other than in the very general sense that a theist may claim "everything is caused by god").

    5. YES! THAT would be a good alternate explanation for her visions!

      I think you wrote that last comment. A good alternate explanation would be, "No, rob's girlfriend snuck onto his computer and typed it." OR: rob's computer is infected with a virus that sends out occasional correct blog comments :-)

      What is NOT a good alternative explanation is: "no, it is just electrons moving around on your screen that made those words show up."

  2. Wow, I did not realize how bad an argument that was until reading this. Thank you for that.