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16 Reasons Why I Believe In God: (6) Consciousness and Identity


A 19th century    phrenology chart    — Wikimedia Commons (Public Domain)

A 19th century phrenology chart — Wikimedia Commons (Public Domain)

If materialism is true, then your mind is nothing more than an emergent property of your brain, or it is one and the same thing as your brain. In either case, there could never be a mind existing apart from a physical brain. Hence, there could be no God (understood as an unembodied Mind). However, if there were good reasons to believe that minds could exist in the absence of a functioning brain, or that minds constitute an irreducibly non-physical part of reality, then it would make God's existence more plausible. As it turns out, there are such reasons. In this post, I will discuss two of them — consciousness and identity.


Our conscious experience of the world has an undeniably qualitative aspect to it. For example, our experiences include things like the color of grass, the sound of a cello, or the feel of pain. Philosophers of mind call these experiences qualia. The existence of qualia poses a problem for materialists. If materialism is true, and all that exists is matter and energy, then all knowledge should be reducible to knowledge of physical/scientific facts. For instance, all knowledge about the experience of pain should be reducible to facts about the stimulation of peripheral nerve fibers, the signals they send to the brain, etc.. If we knew all those relevant facts, then, according to materialism, we should know everything there is to know about the experience of pain. The rather obvious problem with qualia, however, is they show that physical facts do not tell us everything.

A famous thought experiment helps to illustrate this problem, called "the knowledge argument." Imagine a scientist who has lived and studied her whole life in a black-and-white environment. She's never personally seen other colors, but she knows every physical fact there is to know about them — facts about pigmentation, wavelengths of light absorption and reflection, and how the various parts of the brain are stimulated by such wavelengths. According to materialism, she should know everything there is to know about colors and our experiences of them. But then imagine our scientist is allowed to leave her black-and-white environment and, for the first time, she steps outside and experiences the world in all its variegated glory. "Oh, that's what the color green looks like!" we can imagine her saying. Clearly, our scientist has now gained new knowledge that she did not have before, even though she knew all the physical facts prior to going outside. The new knowledge she acquired is qualitative and experiential in nature — it cannot be adequately known simply through physical, descriptive facts. Thus, it seems the qualia of conscious experience entail an irreducibly non-physical component to them. It follows that materialism is false.

Consciousness without the brain?

Qualia create problems for materialism in other ways, too. There are documented cases, although rare, where people claimed to have conscious experiences even though their brains were deemed non-functioning by medical doctors and scientists. NPR told the remarkable story of Martin Pistorius who was effectively "trapped" in his body in a vegetative state for 12 years, after doctors told his parents he was "not there." Then there's the neurosurgeon, Eben Alexander, who claims to have had vivid conscious experiences after his brain was completely disabled by bacterial meningitis — Newsweek covered his story in 2012. Of course, it's possible that people who report such experiences are lying or exaggerating or mis-remembering, or it could be that the doctors and scientists who diagnosed them overlooked something. However, if it were true that people had conscious experiences while effectively brain dead, then that would suggest that consciousness is not something entirely reducible to brain function, as materialists argue.

There are even stranger examples, though. For instance, some people who were cured from hydrocephalus ("water on the brain") as children, now have brains that are mostly just fluid, yet they have normal intelligence and exhibit no noticeable symptoms. This has caused some scientists to ask, "Is the brain really necessary?" All that to say, the materialist conception of consciousness is not without problems.

Leibniz's law of Identity

If materialism is true, then you are identical with your body. You do not have a body, you are your body — "you" and your body are one and the same thing. In other words, there is no immaterial self (or soul) called "you," there is just your physical brain and body. Upon reflection, however, we find that there are excellent reasons to doubt this idea, and therefore to doubt materialism.

According to Leibniz's law, known as the indiscernibility of identicals, if two objects are actually one and the same object, then they should have all the same properties. For instance, the morning star and the evening star should have all the same properties, because, as it turns out, they are one and the same object — the planet Venus. If we discovered a single property that one of them had but the other did not, then they couldn't be the same object, but rather two different objects.

To better understand Leibniz's law, imagine you lost your key fob at the mall. You go to the lost and found to see if they have it, and they ask for a description. You begin to list its properties: "It's black, it's oval shaped, and has a blue-and-white Volkswagen symbol on it." "Sorry," they reply, "we have a Volkswagen fob very similar to that, but it can't be yours — this one is rectangular shaped, not oval." Because their key fob had a single property different from yours (its shape), they understood that it could not be the same object as your key fob. That's Leibniz's law — if two objects are the same object, then they'll have all the same properties. If they don't, then they're not the same object; they're different objects.

Now, if materialism is true, and you are your body, then "you" — that is your self — should have all the same properties as your body. If we found one single property that you have but your body doesn't, then according to Leibniz's law you cannot be the same thing as your body and, consequently, materialism is false. So, is there such a property? Yes.

Identity through time

You persist through time, but your body does not. The cells in your body are constantly being replaced with new cells. A fascinating article in the New York Times, titled "Your Body Is Younger Than You Think," explains:

Although people may think of their body as a fairly permanent structure, most of it is in a state of constant flux as old cells are discarded and new ones [are] generated in their place... The cells lining the stomach, as mentioned, last only five days. The red blood cells...last only 120 days or so on average... The epidermis, or surface layer of the skin, is recycled every two weeks or so... Other tissues have lifetimes measured in years, not days, but are still far from permanent. Even the bones endure nonstop makeover. The entire human skeleton is thought to be replaced every 10 years or so in adults...

According to some estimates, about 98% of the atoms in your body are replaced every 7-10 years or less.[1] You literally do not have the same body that you did ten years ago! But you are still you. The subject we recognize as your self stays the same through time, even though your body doesn't. That's a remarkable fact! If someone took your car and replaced every last part except the steering wheel, you would say it is now a different car, even if it looked identical to the first. Not the same with humans. We do not say that we are literally different people than we were 10 years ago. We sometimes say it figuratively to express how we've grown and changed, yes. But we don't mean that 10-year-ago me is literally a different person than the now me. Yet, we can only say we are the same person if there is something about us that stayed the same through time. Whatever that is, it can't be physical, because most of our body has been replaced multiple times over. Hence, the part of us that stays the same through time must be something non-physical — what we call our self, or our soul.

We've found one property that you have but your body does not — identity through time. Thus, according to Leibniz's law, your self cannot be the same thing as your body; they are two different things. Your body is physical, but your self is irreducibly non-physical. Therefore, materialism is false.

We've seen there are aspects of the human mind that are irreducibly non-physical. Conscious experience and identity through time are two major problems for materialism; there are others I haven't mentioned.[2] It's important to know that it is not just religious believers that think materialism is untenable. A number of non-religious philosophers, and even atheists, openly admit as much. For example, of the three books I've recommended below (all recent publications of Oxford University Press), one is written by an atheist (Nagel), and the other two contain essays by several non-religious or agnostic philosophers.

If materialism is false, then there is more to reality than just the physical. And that leaves the possibility of God and the supernatural wide open.

The argument:

  1. If materialism is true, then irreducibly non-physical minds/selves cannot exist.

  2. God (if he exists) is an irreducibly non-physical mind/self.

  3. So, if materialism is true, then God cannot exist.

  4. However, irreducibly non-physical minds/selves do exist.

  5. Thus, materialism is false.

  6. Therefore, God might exist.

This argument, if successful, shows God's existence is absolutely plausible — i.e. it shows there is no good reason to believe an unembodied Mind can't exist. The arguments I've given prior to this, for the origin, contingency, regularity, and fine-tuning of the universe, and the origin of biological information, if successful, turn God's plausibility into a probability.

Common Objections

1. The scientist who lived in a black-and-white environment did not gain new knowledge when she went outside. She simply gained a new ability — the ability to conceptualize colors in a way she could not before. A newer version of the knowledge argument easily avoids this objection. In the new version (see Laurence BonJour's essay in The Waning of Materialism, pictured below), the scientist is shown samples of two different colors, green and red, before she is ever allowed to go outside. She is not told the names of the colors (only color A and color B), but she is informed that one of them is associated with the experience of freshly mown grass, and the other with a newly painted fire engine. Then she is asked, "Which is which?" At this point, the materialist can't object that the scientist lacks the ability to conceptualize colors, because she has now personally experienced two colors. And the question she is being asked is a purely factual one. But, even though she knows all the relevant physical/scientific facts, she does not know the answer to the question — her knowledge is still incomplete because she lacks the relevant qualia of conscious experience. Hence, the knowledge argument still stands, and materialism is false.

2. The self is merely an illusion. There is no part of "you" that persists through time. I'm sorry, who are you addressing this objection to? If the self is truly an illusion, as you say, then "I" don't exist, and your objection is addressed to no one. If there is no part of me that persists through time, then I am literally not the same person who began writing this blog. That was a different person. Either way, this objection is incoherent.

3. The cells in your brain are not replaced. They persist through time. Hence, you are your brain. This objection has several problems. (1) It's not accurate. As the New York Times article I linked to above explains, some parts of the brain are replaced, such as the olfactory bulb, the hippocampus, and the cerebellum. The part that many scientists believe is not replaced is the cerebral cortex (gray matter). But that's disputed by other scientists, and therefore uncertain. (2) Even if the cortex is not replaced, the entire rest of the body is. So, at what point do we say we are a different person? The illustration I gave earlier is a car that has every single part replaced, except the steering wheel. Even though there is a small part of the car that stays the same, we would still say it's a different car. So, if we are purely physical entities just like the car, why wouldn't we say we are different people, if over 95% of the atoms of our body have been replaced multiple times? Seems inconsistent to me. (3) If you are your brain, or even just your cortex, then conscious experiences like those reported above (assuming they're true) should never happen. If your brain is dead, you are dead.

4. Property dualism (PD) can explain the problems you brought up while still maintaining that everything is ultimately made of matter. A few things: (1) It is not entirely clear how PD can "explain" qualia. It seems a bit fantastic to think that atoms can experience conscious pain, if you just arrange them in the right way. Qualia make much more sense, at least to me, as the experiences of non-physical subjects (selves), which implies a type of substance dualism or hylemorphic dualism. (2) Just like with the previous objection, PD cannot explain conscious experiences in absence of brain function, because, according to PD, we still need functioning brains to have mental properties (consciousness). Again, only a form of dualism could explain that. (3) As I've written about before here, it seems substance dualism, not property dualism, better explains our ethical intuitions about persons. (4) While PD holds that mental properties are not reducible to the physical (which I would agree with), some varieties of PD also hold that mental events/properties are ultimately caused by physical events. So, in a sense, they are reducible, at least causally. But the assumption that mental events are causally reducible to physical events leads to more problems for the materialist; one of these is how to explain the phenomenon of neuroplasticity, in which one's mental activity can physically "rewire" the brain. If mental properties are ultimately caused by physical events in the brain, then mental activity should never be able to physically alter the brain, as it remarkably can. But an even worse problem the assumption leads to is this: materialism cannot explain the existence of reason. I'll say more in my next post.

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Further Reading

*To better understand the goals and limits of this blog series, please read the Introduction, if you haven't already. Thanks!



1. See Lynn Margulis and Dorion Sagan, What Is Life? (New York: Simon & Schuster, 1995), p. 23. They estimate that 98% of the atoms in your body are replaced every year!

2. There are also the problems of intentionality, of mental causation, and of reason, among others. See The Waning of Materialism, pictured above.