Panpsychism It is a belief that consciousness exists in the entire universe—not only in humans and animals, but also in trees, plants, and bacteria. Panpsychists believe that even in elementary particles there are certain aspects of the mind. For intellectual and emotional reasons, broad-minded ideas are attractive to many people. But can it pass the empirical test? Surprisingly, maybe it can. That’s because one of the most popular scientific theories of consciousness, Comprehensive Information Theory (IIT), has many (though not all) features of panpsychism.
As the American philosopher Thomas Nagel It has been argued that if something exists “something” in its state, then it is conscious. The human brain in a waking state feels like something specific.
IIT assigns a unique number, the system’s integration information, which is represented by the Greek letter φ (pronounced as φ). If φ is zero, the system does not feel anything; in fact, the system does not exist as a whole, because it can be completely reduced to its constituent parts. The larger the φ, the more conscious and irreducible the system. Given an accurate and complete description of a system, IIT predicts the quantity and quality (if any) of its experience. IIT predicts that due to the structure of the human brain, the value of φ is very high for humans, while the value for animals is small (but positive), while classical digital computers have almost none.
A person’s φ value is not constant. It increases with self-development in early childhood, and may decrease with the occurrence of dementia and other cognitive impairments. φ fluctuates during sleep, becomes larger during dreaming, and becomes smaller during deep dreamlessness.
IIT first determines the five real and basic attributes of any and every imaginable conscious experience. For example, experience is certain (excluded). This means that the experience is not inferior to reality (experiencing only the feeling of blue, but not experiencing the moving ocean that brings color), nor is it mere experience (for example, experiencing the ocean while also being aware of the canopy behind it). In the second step, IIT derives five related physical characteristics. Any system—brains, computers, pine trees, sand dunes—must be manifested in order to make people feel like something. The “mechanism” in IIT refers to anything that has a causal effect in the system; this may be a logic gate in a computer or a neuron in the brain. IIT says that consciousness only appears in a mechanical system with a specific structure. In order to simplify slightly, the structure must be integrated to the greatest extent-it cannot be accurately described by breaking it down into its components. It must also have a causal relationship to itself, that is, the current state of a given mechanism must not only limit the future state of that particular mechanism, but also the future state of the entire system.
Given a precise physical description of the system, the theory provides a way to calculate φ for the system.The technical details of how to do this are complicated, But the result is that, in principle, as long as there is such a precise description of the system, the φ of the system can be measured objectively. (We can calculate the φ of the computer because we can understand them accurately after constructing them. Calculating the φ of the human brain is still an estimate.)
The system can be evaluated at different levels-one person can measure the φ the size of a sugar cube in my brain, or the φ of my entire brain, or the φ of me and you. Similarly, one can measure the φ of a silicon atom, a specific circuit on a microchip, or a combination of microchips that make up a supercomputer. According to this theory, consciousness exists in the system with the largest φ. It applies to all such systems, and only to such systems.
The φ of my brain is larger than the φ value of any part of it, but someone plans to subdivide it. So I am conscious. But your φ and I are less than my φ or your φ, so we are not “common” consciousness. However, if future technology can create a dense communication center between my brain and your brain, then this brain bridging will create a single thought distributed in the four cortical hemispheres.
On the contrary, the φ of a supercomputer is smaller than the φs of any circuit that composes it, so the supercomputer-no matter how large and powerful it is-is unconscious. The theory predicts that even if some deep learning system can pass the Turing test, it will also be a so-called “zombie”-simulated consciousness, but in fact it is not conscious.
Just like panpsychism, IIT believes that consciousness is the intrinsic and basic attribute of reality. It is graded and is likely to exist widely in the tree of life, because any system with non-zero comprehensive information will make people feel like some kind of thing. This does not mean that the bees feel obese or plan for the weekend. However, when the bee sends the pollen-filled pollen back to the hive in the sun, it will feel a certain degree of happiness. When a bee dies, it no longer has any experience. Likewise, given the enormous complexity of a single cell, with millions of proteins interacting with each other, it might feel a bit like something.
The essence of debate consciousness sounds like an academic exercise at first, but it has real and important consequences. Most obviously, this is important to how we view the vegetative state. These patients may groan or move in other ways for no apparent reason, but are unable to purposely respond to signaling commands by moving their eyes or nodding. Are they conscious, trapped in a damaged body, able to perceive but unable to react? Or are they unaware?
Assessing whether these patients are conscious is tricky. Supporters of IIT have developed a program to test the consciousness of non-responders. First, they built a network of EEG electrodes that can measure electrical activity in the brain. They then stimulated the brain with gentle magnetic pulses and recorded the echo of that pulse. They can then calculate a mathematical measure of the complexity of these echoes, called the Perturbation Complexity Index (PCI).
In healthy, conscious individuals—or in people with brain damage but clear consciousness—PCI is always above a certain threshold. On the other hand, in 100% of cases, if healthy people fall asleep, their PCI is below the threshold (0.31). Therefore, it is reasonable to use PCI as a proxy for conscious existence. If the PCI measurement of a persistent vegetative person is always below this threshold, we can confidently say that the person has no hidden consciousness.
Many clinical centers in the United States and Europe are studying this method. Other tests attempt to verify IIT’s prediction of the location and timing of sensory consciousness footprints in the brains of humans, non-human primates, and mice.
Unlike panpsychism, IIT’s amazing claims can be empirically tested. If they persist, science may have found a way to break a knot that has plagued philosophers since the existence of philosophy.
Christoph Koch He is the chief scientist of the MindScope project at the Seattle Allen Institute for Brain Science.