What are you?
You’d think the answer would be obvious — to you.

Table of Contents

  1. What are You?
  2. Two Kinds of Phenomena
    1. Physical Phenomena
    2. Mental Phenomena
    3. Differences
  3. Two Theories of Persons
    1. Entity Theory
    2. Organism Theory
  4. Big Picture Graphic
  5. Arguments
    1. For the Entity Theory
      1. Self-Awareness
      2. Afterlife
      3. Free Will
      4. Brain Transplant
    2. For the Organism Theory
      1. Hume’s Argument from Introspection
      2. Ockham’s Razor
      3. Nature of Chimpanzees
      4. Mind-Brain Interaction
      5. Parfit’s Split Brain Thought Experiment
        1. Parfit’s Thought Experiment
        2. No Possibility Makes Sense
        3. Nature of Persons
        4. Reductionist and Entity Theories of Persons
  6. Addenda
    1. Anatta / Anatman
    2. Hume’s Bundle Theory
    3. Dualism, Idealism, Materialism

What are You?

What are you?
You’d think the answer would be obvious — to you.

Two Kinds of Phenomena

Physical Phenomena

  • The Universe consists of things big and small: galaxies, stars, planets, mountains, oceans, rocks, molecules, atoms, subatomic particles. It also consists of spacetime.
  • Science has discovered other things as well: forces, electromagnetic radiation, electric and magnetic fields, energy.
  • Finally, there are living things: bacteria, fungi, plants, and animals, including human beings and their parts: organs and tissues, cells and cell parts, and biomolecules.

Mental Phenomena

  • In addition to physical phenomena there are mental phenomena: feelings, sensations, emotions, sense-perceptions, thoughts, moods. For example,
    • A headache, ringing in your ears, joy at the birth of a child, sadness at the death of a loved one, fear of heights, nervousness, back pain, poison ivy itch, afterimages, hunger, fatigue, smell of a skunk, music, taste of orange juice, embarrassment.


  1. Physical phenomena are in theory publicly observable, capable of being observed by more than one person at a time. In contrast, mental phenomena are observable only by the person experiencing them.
    • You have a headache.  We open up your skull, observe your brain, and watch the neurons fire.
      • Your brain and neurons are publicly observable
      • Your headache is privately observable, only by you.
      • I can see your brain but can’t feel your pain.
  2. A person has privileged access to their mental goings-on.
    • It’s self-evident to you that you have a headache.  But I need evidence, such as your moaning, holding your head, telling me you have a headache, lying down, taking Tylenol.  You don’t need such evidence.

View Dualism, Idealism, Materialism

Two Theories of Persons

Entity Theory

  • A person is a being (self, mind, soul, spirit), typically regarded as immaterial, who
    • experiences human mental phenomena
    • has a human body from which it is distinct.
  • From Britannica Article on Soul
    • In religion and philosophy a soul is the immaterial aspect or essence of a human being, that which confers individuality and humanity, often considered to be synonymous with the mind or the self.
  • Religions differ regarding:
    • Whether animals have souls
    • When souls begin to exist
    • When, or if, souls cease to exist
    • How souls are related to the body

Organism Theory

  • A person is human organism that experiences human mental phenomena. There is no being beyond the physical organism and the stream of consciousness associated with its brain.

View Anatta

View Hume’s Bundle Theory

Big Picture Graphic


For the Entity Theory

  • People have a sense of self. When you have a headache you’re not just aware of the headache; you’re aware that you have a headache. When you raise your arm you’re not just aware of your arm rising; you’re aware that you raised your arm.
  • We are thus aware of ourselves. People are self-aware.
  • We’re also aware of our bodies. But the awareness of ourselves is different from the awareness of our bodies. When you’re deliberating about what to do you’re aware of yourself deliberating. But you’re not aware of your body deliberating.
  • Thus we experience mental phenomena. But we are not our bodies. Therefore we are beings separate from our mental experiences and distinct from our bodies.
  • Argument
    • An afterlife would be impossible were a person merely a conscious human organism.
    • But it’s at least possible that we survive our deaths.
    • Therefore, a person is not merely a conscious human organism.
  • View Afterlife
Free Will
  • Argument for Entity Theory
    • A person has free will only if, on at least some occasions, they could have done something other than what they did.
    • A person could have done something other than what they did only if they could have changed the course events in their brain from what it would have been otherwise.
    • A person could have changed the course events in their brain from what it would have been otherwise only if they are distinct from their body.
    • People have free will.
    • Therefore, people are distinct from their bodies.
  • Philosophers disagree about the nature of free will.
    • Hypothetical Free Will
      • A person acts of his own free will if they could have done otherwise if conditions had been different.
    • Categorical Free Will
      • A person acts of his own free will if they could have done otherwise given the same conditions.
  • The Entity Theory presupposes categorical free will.
Brain Transplant
  • If you are a conscious human organism, then you are the same person now that you were when you were a child only if you are the same human organism.
  • But if your brain has been transplanted into different human organism, you are not now the same human organism you were when you were a child.
  • If you are a conscious human organism, then you are therefore not now the same person you were when you were a child.
  • But you are are same person (even though occupying a different body)
  • So you’re not a conscious human organism.

For the Organism Theory

Hume’s Argument from Introspection
  • A Treatise of Human Nature, David Hume, 1739–40
    • For my part, when I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe any thing but the perception. 
    • When my perceptions are remov’d for any time, as by sound sleep; so long am I insensible of myself, and may truly be said not to exist. And were all my perceptions remov’d by death, and cou’d I neither think, nor feel, nor see, nor love, nor hate after the dissolution of my body, I shou’d be entirely annihilated, nor do I conceive what is farther requisite to make me a perfect non-entity. 
    • If any one upon serious and unprejudic’d reflexion, thinks he has a different notion of himself, I must confess I can reason no longer with him. All I can allow him is, that he may be in the right as well as I, and that we are essentially different in this particular. He may, perhaps, perceive something simple and continu’d, which he calls himself; tho’ I am certain there is no such principle in me… But setting aside some metaphysicians of this kind, I may venture to affirm of the rest of mankind, that they are nothing but a bundle or collection of different perceptions, which succeed each other with an inconceivable rapidity, and are in a perpetual flux and movement.

View Hume’s Bundle Theory

Ockham’s Razor
  • Ockham’s Razor, set forth by William of Ockham (1285–1347/49), is the principle that entities should not be multiplied beyond necessity.  The simpler of two theories is preferable, other things being equal.
  • The Organism Theory of Persons is simpler than Entity Theory because it postulates only one kind of entity (conscious human organisms) rather than two (human bodies and persons). A non-body person is a gratuitous middleman between physical and mental phenomena.
Nature of Chimpanzees
  • Human beings and chimpanzees are very alike. Their genomes are 96% identical.  Both have high levels of consciousness. Chimpanzees also seem to be self-aware, having passed the Mirror Test
  • For the Organism Theorist, both are conscious animals.
  • The Organism Theorist, on the other hand, must choose among three views:
    1. Chimpanzees are persons distinct from their bodies, like human beings  (Richard Swinburne)
    2. Chimpanzees are non-conscious automata, philosophical zombies (Rene Descartes)
    3. Human beings and chimpanzees are fundamentally different. Human beings are persons distinct from their bodies. Chimpanzees are merely conscious animals.
Mind-Brain Interaction
  • Descartes held that a person was an immaterial mind that interacted with a human body, making it move and experiencing sensations through its organs.
  • But Descartes went further: he pinpointed the place of interaction, the tiny pineal gland in the middle of the brain. When you bend a finger, your will causes changes in the pineal (PI-knee-ul) gland that radiate through the brain and down the arm, contracting muscles in the hand. When you see a tomato, light waves bouncing off it travel into your eyes, sending signals to the pineal gland that cause a red, tomato-shaped sensation.
  • For many philosophers, the idea of direct, causal interaction between material and immaterial things is incoherent.
Parfit’s Split Brain Thought Experiment

View Two Theories of Persons

  • Derek Parfit, from the Britannica
    • English philosopher whose work in normative ethics and metaethics, personal identity, and the theory of practical reason was widely influential in the English-speaking world from the 1980s. Many of his peers considered him the most important moral philosopher of the 20th and early 21st centuries.
    • The publication of Parfit’s first book, Reasons and Persons (1984), created a sensation among English-speaking academic philosophers, who were impressed by its originality, its intricate and ingenious argument, its immense fertility, and its panoramic scope. 
  • From Parifit’s Reasons and Persons, Page 275
    • “I distinguished two views about the nature of persons. On the Non-Reductionist View, a person is a separately existing entity, distinct from his brain and body, and his experiences. On the best-known version of this view, a person is a Cartesian Ego. On the Reductionist View that I defend, persons exist. And a person is distinct from his brain and body, and his experiences. But persons are not separately existing entities. The existence of a person, during any period, just consists in the existence of his brain and body, and the thinking of his thoughts, and the doing of his deeds, and the occurrence of many other physical and mental events.”
Parfit’s Thought Experiment
  • Preliminary Thought Experiment #1: Brain Transplant
    • Suppose first that I am one of a pair of identical twins, and that both my body and my twin’s brain have been fatally injured. Because of advances in neurosurgery, it is not inevitable that these injuries will cause us both to die. We have between us one healthy brain and one healthy body. Surgeons can put these together.
  • Preliminary Thought Experiment #2: Hemispherectomy
    • There are many people who have survived, when a stroke or injury puts out of action one of their hemispheres. With his remaining hemisphere, such a person may need to re-learn certain things, such as adult speech, or how to control both hands. But this is possible. In my example I am assuming that, as may be true of certain actual people, both of my hemispheres have the full range of abilities. I could thus survive with either hemisphere, without any need for re-learning.
        • Hemispherectomy is a very rare neurosurgical procedure in which a cerebral hemisphere (half of the upper brain, or cerebrum) is removed, disconnected, or disabled.
      • Meet the ‘glass-half-full girl’ whose brain rewired after losing a hemisphere NPR
        • When she was 9 months old, surgeons removed the left side of her brain. Yet at 15, Mora plays soccer, tells jokes, gets her nails done, and, in many ways, lives the life of a typical teenager.
        • Yet to a remarkable degree, Mora’s right hemisphere has taken on jobs usually done on the left side. It’s an extreme version of brain plasticity, the process that allows a brain to modify its connections to adapt to new circumstances.
  • Preliminary Thought Experiment #3: Hemispherectomy + Half-Brain Transplant
    • I shall now combine these last two [thought experiments]. I would survive if my brain was successfully transplanted into my twin’s body. And I could survive with only half my brain, the other half having been destroyed. Given these two facts, it seems clear that I would survive if half my brain was successfully transplanted into my twin’s body, and the other half was destroyed.
  • Parfit’s Thought Experiment: Hemispherectomy +  Two Half-Brain Transplants
    • My body is fatally injured, as are the brains of my two brothers. My brain is divided, and each half is successfully transplanted into the body of one of my brothers. Each of the resulting people believes that he is me, seems to remember living my life, has my character, and is in every other way psychologically continuous with me. And he has a body that is very like mine.
No Possibility Makes Sense
  • So what happened to me? There are four possibilities:
    • (1) I do not survive;
    • (2) I survive as one of the two people;
    • (3) I survive as the other;
    • (4) I survive as both.
  • The objection to (1) is this. I would survive if my brain was successfully transplanted. And people have in fact survived with half their brains destroyed. Given these facts, it seems clear that I would survive if half my brain was successfully transplanted, and the other half was destroyed. So how could I fail to survive if the other half was also successfully transplanted? How could a double success be a failure?
  • Possibilities (2) and (3) are that I shall be one of the two resulting people. The objection here is that, in this case, each half of my brain is exactly similar, and so, to start with, is each resulting person. Given these facts, how can I survive as only one of the two people? What can make me one of them rather than the other?
  • Possibility (4). The problem with double survival is that it does not fit the logic of identity. I and the two resulting people cannot be one and the same person. Since I cannot be identical with two different people, and it would be arbitrary to call one of these people me, we can best describe the case by saying that neither will be me.
Nature of Persons
  • Entity Theory of Persons:
    • A person is a separately existing entity, distinct from their brain and body, and their experiences. The best-known version of this view is that person is a Cartesian Ego.
  • Reductionist Theory of Persons (Parfit’s View)
    • A person is distinct from their brain and body, and their experiences. Persons exist. But they are not separately existing entities. The existence of a person, during any period, just consists in the existence of their brain and body, and the thinking of their thoughts, and the doing of their deeds, and the occurrence of many other physical and mental events.
    • Consider a political party which splits and becomes two rival parties. We can ask, ‘Did the original party cease to exist, or did it continue to exist as one or other of the resulting parties?’ But we do not believe that this is a real question, about different possibilities, one of which must be what happened. This question is empty. Political parties exist.  But they are not separately, or independently, real.
    • As with political parties, the question of what happens to me in the thought experiment is not “a real question, about different possibilities, one of which must be what happened.” A person is not an entity whose existence is separate from the existence of their brain and body, and the occurrence of their experiences. 
  • Wikipedia on Democratic-Republican Party
    • After the 1824 presidential election the Democratic-Republicans split into factions. The coalition of Jacksonians, Calhounites, and Crawfordites built by Andrew Jackson and Martin Van Buren coalesced into the Democratic Party, which dominated presidential politics in the decades prior to the Civil War. Supporters of John Quincy Adams and Henry Clay would form the main opposition to Jackson as the National Republican Party, which in turn eventually formed part of the Whig Party, which was the second major party in the United States between the 1830s and the early 1850s.
Reductionist and Entity Theories of Persons


Anatta / Anatman

    • In Buddhism, Anatta is the doctrine that there is in humans no permanent, underlying substance that can be called the soul.
    • The Buddha rejected the existence of the soul as a metaphysical substance, though he recognized the existence of the self as the subject of action in a practical and moral sense. Life is a stream of becoming, a series of manifestations and extinctions. The concept of the individual ego is a popular delusion; the objects with which people identify themselves — fortune, social position, family, body, and even mind — are not their true selves. There is no permanent, underlying self.
    • To make clear the concept of no-self (anatman), Buddhists set forth the theory of the five constituents (khandhas) of human existence:
      • (1) corporeality or physical forms (rupa),
      • (2) feelings or sensations (vedana),
      • (3) ideations (sanna),
      • (4) mental formations or dispositions (sankhara), and
      • (5) consciousness (vinnana).
    • Human existence is only a composite of the five aggregates, none of which is the self or soul. A person is in a process of continuous change, and there is no fixed underlying entity.

Hume’s Bundle Theory

    • The Bundle theory was advanced by David Hume to the effect that the mind is merely a bundle of perceptions without deeper unity or cohesion, related only by resemblance, succession, and causation. Hume’s well-argued denial of a substantial or unified self precipitated a philosophical crisis from which Immanuel Kant sought to rescue Western philosophy.

Dualism, Idealism, Materialism

  • Dualism: The mental and the physical are distinct phenomena.
  • Materialism: Mental phenomena are a kind of physical phenomena.
  • Idealism: Physical phenomena are a kind of mental phenomena.