Where and What: Two Experiments for Dualism

Introduction

The philosophical background of neuroscientific research is very important. If we choose one or another philosophical position about the composition of the mind, we have strong consequences about what is the object and what should be the methodology of neuroscientific research.

Actually, we can think about three main positions about the composition of the mind: The substance dualism, the property dualism and the materialistic reductionism. The substance dualism maintains that the mind and the brain are two completely distinct things but that can interact with one another. The materialistic reductionism says that there is, talking about the mind, one and only one reality: the material reality. The property dualism, instead, argues that what composes the mind is partly material and partly immaterial.

From a logical point of view, we can exclude the substance dualism as contradictory. The mark of material reality is in fact causal efficacy, and if the immaterial substance of the mind can interact causally with the material substance of the brain, we have to consider that the immaterial substance is erroneously considered as such. If the immaterial substance interacts causally with the material substance of the brain, we have to consider the immaterial substance of the mind something material too.

In what follows I will discuss two interesting neuroscientific experiments to argue in favor of the dualism of properties and show that mental reality is partly material and partly immaterial. I will argue from an empirical point of view in favor of such a background; consequently the point of view of materialistic reductionism will fall.

In 2007, two experiments that have now become very famous have appeared in the literature. Henrik Ehrsson and Bigna Lengenhagger produced, in healthy subjects, out-of-body experiences. The literature reports this kind of experience as a consequence of neurological disease or drug use. In this article, I will show that the experiments' outcomes, for how they are designed, "argue" in favor of a philosophical position called dualism and, in our case, of that dualism called dualism of properties.

I will describe the experiments and the findings to make clear the authenticity of the experience involved. Once shown the authenticity of the out-of-body experiences involved, I will abandon the problem of how the experimenter obtained them. I will discuss then why these findings under-determine a philosophical position as dualism and what kind of dualism we should think about.

Two Experiments from 2007

Henrik Ehrsson defines the out-of-body experience "as the experience in which a person who is awake sees his or her body from a location outside the physical body" (Ehrsson, 2007). We can observe these phenomena in patients with stroke and in other abnormal personal conditions as in those who habitually use drugs.

The scientist speculates and experiments that they can induce a similar condition even in healthy patients. First, Ehrsson puts a camera two meters behind the subject. The camera "sees" the back of the subject and transmits the left image of the camera to the left eye of the subject and the right image of the camera to the right eye. The subject now sees his back as if it were in the same spot as the camera.

To stimulate the out-of-body experience, the scientist touches the subject's chest with a rod and shows the same action to the camera without the subject being visible. This experimental apparatus provokes the illusion of looking at one's body from an external point of view. Ehrsson states: "the participants reported the experience of sitting behind their physical bodies and looking at them from this location" (Ehrsson, 2007).

He hypothesized that "the illusion is caused by the first-person visual perspective in combination with the correlated visual and tactile information from the body" (Ehrsson, 2007). To demonstrate this hypothesis, Ehrsson "hurts" with a visible hammer the illusory body of the subjects and he obtains a bodily experience as if the subject was really in the illusory position.

In a similar experiment from 2007, Bigna Lengenhagger and colleagues reach a similar outcome from the experimental conditions. The subject has an out-of-body experience when in virtual reality the bodies are captured by a camera and reproduced in a different position, in front of the subjects and from the backward, when they are synchronously stimulated by a rod.

In the synchronous condition, the subjects state that their position in the experimental set is that of the illusory body perceived by the virtual reality as their own real body. As in Ehrsson 2007, what the experimenter induces is a proper out-of-body experience. The experiment is therefore reproducible and falsifiable. What I will discuss now is the philosophical and theoretical outcome of these experiments.

The Set of the Experiments

First, we must separate the wheat from the chaff and we have to ask ourselves "What is seen in the experiments by the subjects?" Without the physical stimulation and the production of the proper out-of-body experience, we would be in a strange condition. What the subjects see is simply the images of the camera that projects the observer's body from a particular point of view.

The subjects in that condition do not report any particular strange experience; there is not any illusory body and, even if they report their body position as that in the videos, one could explain the experience like an error in perception. This is not the case because, as seen, the subjects do not commit an error like this. The illusory bodies are something more than the perception of their bodies by the subjects. They have the perception of the body and of the bodily sensation as they were in a position other from what they really are.

The stimulation of the body and the stimulation of the illusory bodies, the body that would be stimulated if it were really out there, as in sleight of hand, permits the subject to prove an out-of-body experience. Moreover, Ehrsson shows that there really is an illusory body linked to well-defined body perceptions.

In fact, when he tries to "hit" the illusory body of the subjects with a hammer where it should be according to what they reported in accordance with the experimental conditions and with the extracorporeal experience, the response of the real body is similar to that of a body that a hammer is going to hit. The experience caused in the experiments is not the perceptual experience alone. It is the experience of the subject to be in a different position despite that where its body really is.

Out of Body Experience and Dualism

One of the questions that seems to be prominent to us is "Where is the body experienced in the experimented out-of-body experience?" The body experienced in the out-of-body experience is not where the body is but is not elsewhere in the experimental set. There is an experience not congruent with the experience that the subject should have in normal condition.

The out-of-body experience and the normal experience have the same character. The first experience does not properly link the body while the second does. It is easy to infer that the "where" of the out-of-body experience is not the "where" of the body.

The normal experience and the out-of-body experience are similar. The "where" of the out-of-body experience and the "where" of the body are distinct two. There is nothing, in the set of the experiments, where the subjects indicate and feel they are. Under the hypothesis that the "where" of the experience is the same in the out-of-body experience with respect to what should be the normal one, we can say that the "where" of experience is different from the "where" of the body.

My hypothesis is hard to deny. If the "where" of the normal experience is different from the "where" of the out-of-body experience and the same of the body, we should say contradictorily that the same kind of thing, an experience, has sometimes a kind of "where" and sometimes a different kind of "where". The first physical should be where the body is, the second in a different kind of place.

The results are simply to demonstrate from the identity and distinction between the "where" of the objects and experiences.

The experience has no causal efficacy except with the body and we can say that our result is in favor of some form of dualism. The experiments show that the mental reality is at least triadic. There is the electrochemical level, the plan of the experience and the neural effects on the body. The Ehrsson's hammer test is revealing in this sense.

The experimenter goes to strike the illusory body and the experience causes a physical response in the subject. We have to note that, the normal experience, unlike the out-of-body experience, links the body in such a way that there is an agreement between the "where" of the body and the "where" of the experience. In the out-of-body experiences, this agreement is lost.

Now a reductionist might say that the experiment shows explicitly that the electrochemical level is the same as experience. In this case, we could answer that, as seen, the "where" of the experience is not the "where" of the brain and that the "where" of experience is not the "where" of the electrochemical processes inside the brain. The fact that a change in experience corresponds to a change in electrochemical activation is not a problem for the property dualist.

We are not forced to say, contradicting ourselves, that the immaterial part causes a physical change, as in the dualism of substances, precisely because the immaterial is a part of the whole as an object that is partly material and partly immaterial is constituted. Think of a bag as an abstract object. Both by breaking up the bag with scissors (our material part) and by unstitching the seams (our immaterial part) the bag is no longer there.

The normal conditions make me think that there must be a specific correlation between the coordinates of the physical "where" and the coordinates of the "where" of the experience because, in everyday life, when I touch my hand in the experience I touch it in the physical world too. The out-of-body experience, on the other side, shows that after all the task of the senses is to be able to represent any type of experience.

There must be a precise mathematical correlation between what I encounter in experience and what I encounter in the physical world. Precisely because we must be able to investigate the physical world before any contact with it, we must be open to any type of experience. The abstractness of the mathematical relations makes this meeting possible and ensures that a reference system, a "where", can be put in relation with another reference system, another "where".

This line of reasoning leads us to one of the classic Kantian motifs. As for the time and space of Kant's transcendental aesthetic, our whole experience is the transcendent representation of the physical world and as a palette contains the possibility of any painting, so the forms of experience, time, space, colour, form, contain the possibility of representation of any experience in the physical world (Kant, 1781).

The second metaphysical claim is that the natural knowledge at a transcendental and naturalistic level is the "knowledge" and the "needs" shaped by natural selection. The shape that evolution makes. In this sense, humans have to be open to every kind of experience and only to some kind of experience both because, to live, they have to be open to the environment before they really know something about it, but they have to possess at least some instruments to live it for what it is. This is because natural selection is not only a physical but a metaphysical dispositive too.

The findings tend to demonstrate that self-consciousness can be separated from the physical body and to be something pertaining to the experience built up from the mind-brain. This is a second and important experimental point for dualism. It is hard to see how the nature of experience, distinct from the physical body, can be reduced to the electrical activity of the brain.

The experience of the subject is the experience to be out of his body and to see it from an external point of view. This entire experience is what we should reduce to the electrical activity of the brain. We can do that if and only if the electrical activation has a part of qualitative properties like colours of our out-of-body experience, in such a way that the qualitative experience is the mental counterpart of electrical activity of the brain.

This is the logical conclusion of an inference that wants what has not causal power as something that cannot interact causally and directly with something other. If we think of the mind as something qualitative that has no direct causal powers, while brain activation has, we can sustain this kind of dualism. As the property-dualism wants, we can think of a dualism that says that brain activity comprehends a material and an immaterial part.

This is the dual nature of experience as something different from the physical world. As for the "where" we can reason about the "what". The out-of-body experience is something different from what is the physical environment. The experience to be in a place of the experimental set and to see one's own body from the outside is distinct from everything in the experimental set, the physical "what".

Under the hypothesis that the "what" of normal experience has the same nature as the out-of-body experience, then the "what" of the normal experience is something distinct from the "what" of the physical environment. That can be proved with a demonstration similar to the "where" case. The hypothesis is hard to deny. We should admit that sometimes the experience is something physical and sometimes something different.

Conclusion

The experiments of Ehrsson and Bigna Lengenhagger and colleagues show that they can induce in normal subjects out-of-body experiences. In the out-of-body experience, the "where" and "what" of the experience are different from the "where" and "what" of the physical subjects in its environment, in our case in the experimental set. The "where" and "what" of the out-of-body experience is beyond reasonable doubt the same as the normal experience. Then, "what" and "where" of the experience is something different from the "where" and "what" of the physical set. The experiences have in fact no causal powers, as we have understood them.

If what I have shown is true, the findings of Henrik Ehrsson and Bigna Lengenhagger can be used to validate the theory that argues, the dualism, that the experience of the subject and the physical environment are two distinct things. Theoretically, the theory preferred is the property dualism of the mind-brain opposite to the substance dualism that for logical and practical reasons we have shown is hard to assert.

In other words, the experiments under-determine a theory showing that there are two worlds distinct one from the other: the experiential world and the physical world. The first can communicate with the body and is at least in part physical as the brain signal, but we should equally consider it something different from the second.

Data availability

None declared.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.