Science and the Search for the Soul (1): Psychology, Physics, and Metaphysics
Are humans nothing but a conglomerate of physical particles behaving in accordance with physical laws? Can we show that the existence of a soul and an afterlife are scientifically impossible? Is agnosticism a viable alternative? My proposal to overcome a deadlocked metaphysical debate.
“You,” your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules. As Lewis Carroll’s Alice might have phrased it: “You’re nothing but a pack of neurons.”
This is The Astonishing Hypothesis, the basic idea the neuroscientist Francis Crick (1916-2004, Nobel Prize for Physiology or Medicine 1962) explained in his homonymous book on consciousness, first published in 1994. The subtitle of the book, “The Scientific Search For the Soul”, does not refer to the identification of an immaterial entity that religious and spiritual doctrines sometimes refer to. Instead, Crick tries to explain human perception, emotion, cognition, and behavior scientifically, particularly by means of brain research.
Many philosophers from ancient times until today have speculated about the existence and function of a soul, others have tried to avoid metaphysical conundrums by referring to the human “mind”, which may be understood more innocently as the set of our mental capacities, such as calculating, feeling, deciding, and so on – mental capacities whose triggers and consequences we commonly can observe, in ourselves as well as others.
A major knowledge gap: The mind
In spite of the successes of the cognitive and neurosciences of the recent decades, it is still a challenge to understand the mind and consciousness, called one of the major knowledge gaps in a special edition of Science in 2005, together with such questions as what the universe is made of and whether there is extraterrestrial life.
One of the particular problems of consciousness is already the definition of the phenomenon in the first place – and this does not only apply to consciousness, but to our psychological processes in general. Psychologists are trained to operationalize their theoretical constructs, they provide definitions suitable for experimentation and observation. Examples are attention, conflict, desire, or personality. Subsequently they can investigate them and perhaps even make predictions about human behavior; but psychologists are usually not metaphysicists speculating about what these processes “really” are.
There is no simple brain-mind-mapping
Neuroscience has not helped to solve this problem so far. The hope that modern methods of brain research might allow us to “carve nature at its joints” in the domain of psychology has not been fulfilled. Perhaps you have already heard that the next edition of the North American handbook of psychiatric disorders expected to be published next year, the DSM-5, does not give one single positive example of a neuroscientific definition of a psychological disorder, although it lists about 400 of such pathological conditions. In the related domain of psychiatry, thus, “carving nature at its joints” neuroscientifically has not been successful so far; but let us stick to psychology here.
Instead of clarifying the psychological ontology, the entirety of our psychological processes, many neuroscientists reproduce the sometimes fuzzy or ambiguous concepts such as “reason” or “emotion” and report brain correlations for them. However, our brains do not seem to work in such a way that there are unique patterns of cellular processing that correspond to at least some psychological processes.
The patterns found are subject to a lot of variability due to, among others, general metabolic processes, individual differences, and other sources interfering with the measurement technology. It may be that future neuroscience will provide better methods to identify unique patterns of our mind in the brain. Given common views on the brain as realizing the mind this is actually what we would expect, but for the time being this remains somewhat optimistic speculation.
From physics to people
Does this mean that we have to remain silent about the nature of the mind or the possibility of the existence of a soul? The physicist, science writer, and blogger Sean Carroll argues that the basic physics underlying our everyday life is completely understood and consists of three kinds of particles, electrons, protons, and neutrons interacting via three forces, nuclear forces, gravity, and electromagnetism. He claims – see also this video of his great talk at The Amazing Meeting 2012 in Las Vegas – that Quantum Field Theory leaves no possibility for any additional kinds of particles or forces on the level of our everyday life.
Here I have to admit that I have hardly more knowledge of modern physics than what I have learned at High School, perhaps with a bit of superficial extra knowledge of the philosophy of physics; but for the sake of my argument, let me just assume that Carroll is right. From the said physical understanding he derives the impossibility of the existence of a soul or an afterlife. In his own words:
Claims that some form of consciousness persists after our bodies die and decay into their constituent atoms face one huge, insuperable obstacle: the laws of physics underlying everyday life are completely understood, and there’s no way within those laws to allow for the information stored in our brains to persist after we die. If you claim that some form of soul persists beyond death, what particles is that soul made of? What forces are holding it together? How does it interact with ordinary matter?
If this conclusion is correct, then physics would show that certain spiritual and religious beliefs common in some cultures are wrong; more astonishingly, physics would actually already have shown this decades ago without those believers noticing or adapting their beliefs. Before I continue, let me clarify that I do not know any convincing arguments in favor of immaterial souls or the possibility of an afterlife; but so far I was convinced that this problem is not solvable and that it is thus best to remain undecided, a position sometimes referred to as agnosticism (see also this brief exchange on the stance of agnosticism regarding life after death between Adam Frank and Alva Noë).
Serious ramifications or a humble alternative?
Thus, if Carroll’s conclusion that modern physics rules out such possibilities is correct, then we should expect serious ramifications. Not only for scientists and philosophers it is important to avoid contradictions in their theories and belief systems. However, I think that even if his presentation of modern physics is correct, his conclusion is not mandatory: For if the physics underlying our everyday life is completely understood and this understanding is based on the three kinds of particles and forces, all we can require is that theories about processes or phenomena of our everyday life do not contradict physics.
You may ask yourself what the difference is and whether it is important. In philosophy, there is a stance called physicalism that holds that everything that exists is (ultimately) physical, or that all that can be explained can be (ultimately) explained physically, just to give you two variants, one about existence (that we might call “ontological”) and one about explanations (that we might call “epistemological”). Again, similar stances have been proposed already ages ago. As I understand Carroll, he is a modern (and intelligent) physicalist of some sort. While he admits that there is still much that we do not know, he obviously gives physics a special status, as the physics underlying our everyday world has implications for this world.
In the second part I will argue that physics is not the only academic discipline that has a say about which entities exist. Physics cannot force us to exclude other sciences but all we need is compatibility.