The divided brain and the making of the Western world

By: Iain McGilchrist

Published: 2009

Read: 2020

Summary:

The two hemispheres of our brain (left and right) differ in coherent neuropsychological, anatomical, physiological and chemical ways.

Part 1 explores how differences between the left and right hemisphere affect our experience of the world, most importantly by affecting the type of attention we pay to the world.

Our two hemispheres deliver two different ‘versions’ of the world: the left is about division (focused attention, break things into parts, abstract reasoning, the individual) and the right is about unity (broad attention, the whole rather than the parts, context, relations to the world and others). Both versions are authentic and valuable.

The two hemispheres need to cooperate and the differences between them provide the basis for a suggested sequencing of cooperation from the right to the left and then back to the right hemisphere:

1. Right: explore, new experiences (the whole).
2. Left: focus, explain what has been selected (its parts).
3. Right: meaning through integration (into a whole larger than the sum of its parts).

Which hemisphere’s version of the world predominates determines our experience of the world. While every activity is served at some level by both hemispheres, for some activities, we consistently prefer one hemisphere over the other. While the differences may be small, they compound and can lead to large biases in how we experience the world over time.

While both hemispheres ideally should cooperate, they seem to be involved in an ongoing power struggle. Recently, the left hemisphere seems to be winning, resulting in a potentially overly analytic and reductionist view of and approach to the world. This may lead to hubris and excessive confidence in our ability to understand and control complex situations.

Part 2 explores how the structure of the brain and successive shifts in balance between the hemispheres have influenced the course of history and have shaped our world.

Worth Reading:

A philosophical investigation into the left and right side of the brain that is deeply researched and densely written. The richness and variety of its references makes the book a highly original read.

The most convincing part of the book is where it describes the differences between the two halves based on neurological observations, thoroughly debunking a lot of pop psychology on left versus right hemisphere characteristics.

On the philosophical side, there are many interesting concepts and dualities explored in the book, such as the role of paradoxes and metaphors in the acquisition and transfer of knowledge.

On the neurological side, the exploration of domination by the left or right brain and its impacts on human behavior has many interesting links to personal experiences (for instance, how your enjoyment and understanding of music, books, art may change over time). 

The main issue is that the book’s focus is narrow. It leans heavily on observations from philosophy and psychiatry and mostly ignores the brain’s mechanics, such as its biology, neurophysiology and the way it processes information. When you set out to examine the influence of the structure of the brain on human behavior and society, without grounding it in the nuts and bolts, it becomes difficult to convincingly answer certain questions.

It is very difficult to answer why the brain is separated laterally, if and why information pings back and forth between the two halves, if any side dominates, etc., without much discussion of the brain’s overall hierarchy, its methods of (predictive) information processing, the impact of hormones, neurotransmitters, etc. As a result, the answers provided are not very convincing and generally lack evidence. For instance, what if the brain is simply divided into two halves because this increases the surface area of the brain, making it easier to cool it down? What if function follows structure, instead of structure following function, as argued in the book? This probably has implications for the book’s other claims (the need for separation, cooperation, competition, power struggles, etc.)

Also, the lack of a thorough understanding of and grounding in the brain’s mechanics and processes makes it difficult for the book to offer practical solutions to the issues it identifies. For instance, the book fairly highlights the dangers of an overly reductionist take on life and how this may result in an unwarranted and exaggerated  sense of control over the environment. Perhaps Part 2 does a better job of offering solutions for this, but based on Part 1, the answer would be: a magical, willed return to the right side of the brain to achieve more awe, wonder and empathy.

Other books (including “Blueprint“, “How to Change Your Mind“, “The Genius Within”, “On Intelligence“) do a better job in exploring relevant brain mechanics and processes and frame questions and answers in a way that allows for more practical takeaways. 

Ultimately, what is needed is not replacing conceptual thought with empathy, awe and wonder, but improving our understanding of the increasingly complex processes that we investigate through conceptual thought. This requires an active open mind, discovering hidden logic, exploring different time frames, analyzing processes and where possible, reducing non-linear problems to linear rules that can be more helpfully employed in our decision making.

Key Takeaways:

• The brain works mainly through inhibition.
  • Preventing the inappropriate response, rather than producing the right one.
  • Related: free won’t, rather than freewill.
• All cognition is a process of recognition.
  • We recognize something only if we already have a model in our brain.
• Knowledge relies on distinctions.
  • We can’t experience something unless there is a change or difference.

Key Concepts

Brains are asymmetric, consisting of a left and right hemisphere

• As brains evolved, they grew bigger, less interconnected and more asymmetric.
  • Resulting in the creation of two autonomous hemispheres (left and right).
  • Connected through the corpus callosum:
    • A band of neuronal tissues connecting the two hemispheres.
    • Its primary effect however is to allow one hemisphere to inhibit the other.
• Division and asymmetry likely due to functional requirements.
  • Structure follows function: for instance, brain areas grow in response to (more) usage.
• Functional requirements: evolutionary pressures of competing, incompatible needs:
  • Getting, feeding requires narrow focus.
  • Guarding and relating to others requires broad focus.
• Adaptive response: the brain attends to the world in two separate ways.
  • Brings into being two separate worlds.
  • Avoids conflicts and interference.
• Results in lateralization of attention, asymmetry:
  • Left = focus, experience, broken into parts, abstract, individual.
  • Right = breadth and flexibility, plan, whole, context, bonding.

 Each hemisphere has a different way of paying attention to the world

• Right hemisphere:
  • Broad attention, ability to adjust breath of attention.
  • New information, flexibility of thought, distant relationships, unpredictable situations.
  • Widely connected, synthesizing distant connections, comes first.
  • Context: indirect interpretation, unique instances, relations between things.
  • Individual, identify unique, complex shapes.
  • Living, inter-connectedness, empathy.
  • Social, empathy, emotional perception and expression.
  • Uncertainty, maintain ambiguous thoughts.
  • Pessimistic.
  • Morality, connection to sense of self and others.
• Left hemisphere:
  • Focused
  • What it knows, prioritizes the expected, predictive, routine situations.
  • Connected within itself (with what it knows), local view, follows.
  • Abstraction: explicit labels, internal logic, invariant representations of the world.
  • Categories, classify non-specific objects, simple shapes.
  • Impersonal.
  • Non-living, man-made objects, utility.
  • Certainty, needs to be right, confabulation.
  • Optimistic.
• In short:
  • Left: division.
  • Right: unity.
• Caveats:
  • Complex tasks are harder to localize.
    • Widely distributed across an array of pathways in the brain.
  • Only effortful tasks can be measured.
  • It is not what is done, but how it is done, that distinguishes the two hemispheres.

The way each hemisphere pays attention changes the way we see the world

• Each hemisphere produces a different way of being in the world.
  • The direction and nature of our attention changes the world around us and ourselves.
    • Changing the world: the way of looking at a thing changes its nature.
    • Changing us: we objectively change depending on what or who we pay attention to.
  • “Whatness” and “howness”.
    • Whatness: matter (brain), reducible to its components, disparity.
    • Howness: a process (mind), a becoming, irreducible way of being, unity.
  • Immediacy and distance.
    • Immediacy: broad, lived experiential world.
    • Distance: stand back from experience, plan, think, trust, take control.
• Attention from the left hemisphere produces:
  • Language and abstraction.
  • Clarity and power to manipulate things that are known, fixed, static, isolated.
  • Relationship of purpose (utility).
• Attention from world of the right hemisphere produces:
  • Individual, changing, evolving, interconnected, implicit, context.
  • Never fully graspable, always imperfectly known.
  • Relationship of care (empathy).

These differences drive attention from right hemisphere to the left and then back to right again

• Temporal hierarchy of attention.
  • First – right:
    • Latent, experiential (pre-conscious) concepts, primed.
    • Exploratory attention, new experience.
    • Determines what we pay attention to (it changes us).
    • Intuitive apprehension of whatever it may be
  • Then – left:
    • (Conscious) understanding by awakening the latent model.
    • Focus, grasping what has been prioritized, the familiar and routine.
    • Enrichment through conscious, detailed analytic understanding.
    • What we pay attention to, determines what we see (we change it).
  • Last – right:
    • We (unconsciously) chunk it.
    • Integrating what has been identified.
    • Enhanced intuitive understanding of the transformed whole
• Everything starts in the right hemisphere:
  • It directs our way of being in the world.
    • Emotion and our body are at the core of experiencing the world.
  • It drives our way of attending and relating to the world.
    • First filter.
  • Something particular is permitted to come into being for us.
    • Broad attention before focused attention.
    • The whole before division into the parts.
    • The new before the routine.
    • Gestures before language.
    • Association (metaphors) before analysis.
    • Feelings before reason (cognition comes later).
  • Judgment is not dependent on the outcome of a conscious, cognitive process.
    • Intuitive assessment of the whole comes before cognitive processes.
    • Presence of the pre-conscious mind.
• Followed by the conscious processing of the left hemisphere:
  • Providing focus, fixity and clarity.
    • Developing a certain type of knowledge at a certain level of focus.
  • To know something clearly is to know it partially only.
    • To know it, rather than to experience it, in a certain way.
  • Use consciousness to explain and justify our intuitive choices.
    • Conscious representation: language, awareness.
    • Illusion of control, origination.
    • Too much: alienation, estrangement.
  • Second filter: further narrowing of focus.
    • Allowing for control, manipulation.
    • Breaking the whole into into parts.
    • Unpacking the implicit.
    • Using language for serial analysis.
    • Categorization and cognitive abstraction.
• Followed by the right hemisphere again:
  • Providing ultimate meaning, grounded in experience.
    • Back to the whole picture level.
    • Depth, context.
  • What was conscious, becomes unconscious again.
    • Contact with the embodied world.
  • Need for ultimate unification, division with union.
    • Two opposing principles harmonized again.
    • Subject rational workings of the left to intuitive wisdom of the right.
• All cognition is a process of recognition.
  • We recognize something only if we already have a model in our brain.
• Generally, a process of inhibiting, negation.
  • Prevent the inappropriate response, rather than producing the right one.
  • Free won’t, rather than freewill.
• Seems to be more of process of frontal lobes versus more ancient brain regions.
  • Right is more connected to ancient, sub-cortical brain regions.

… underscoring the need for hemispheric cooperation and integration

• The two hemispheres have complementary but conflicting tasks.
  • They need to share (cooperate) as well as separate (compete) information.
• Healthy relationship between the hemispheres requires the right balance of sharing/separating.
  • Corpus callosum maintains separation between the hemispheres.
    • Facilitates process of information transfer / inhibition.
  • It is important that “things” end up back in the right hemisphere to be integrated again.
    • The left is never the starting point or end point, never the deepest, or the final, level.
    • The left hemisphere is the intermediate level of the ‘processing’ of experience.

… but things seem to get stuck in the left.

• At the level of unconscious engagement with the world both hemispheres operate independently.
  • Low level tasks don’t require conscious integration.
  • Separation and mutual inhibition.
• At the level of conscious experience of the world, one hemisphere (the left) may dominate.
  • Consciousness is a process that starts (unified) at the lowest levels.
    • Involving automatic brain processes below the two spheres that prepare for action.
    • Experience is already coherent at very low levels in the brain.
  • As consciousness moves up to higher levels, may “end up” in left or right hemisphere.
    • Each hemisphere may interpret rising consciousness differently.
  • Once there, the left is better at suppressing the right hemisphere than vice versa.
    • Either/or (left) instead of context, the whole (right).
• This is due to asymmetries between the hemispheres.
  • The balance of power should be with the right hemisphere:
    • The hemisphere that is connected with the real world, provides grounded meaning.
  • But it seems to be with the left:
    • Derives its power from arguments: access to language, logic, linearity.
    • Driven to stay within its own enclosed world: reflexive, self-referential.

… associated with a reductionist approach to a complex world

• The role of science and philosophy has mostly been to bring order to nature.
  • Patient and detailed attention to the world.
  • Instead of awe, wonder.
• Both science and philosophy are left-brain, reductionist approaches.
  • Understanding is built up from the parts.
    • The whole is the sum of the parts that can be reached through increments.
    • Sequential, linear.
    • Division: “either/or”, separation, static.
    • What is seamless in the world is broken up.
  • Driven by utility, maximizing of individual gain.
  • Truth is abstraction, certainty.
• Something is often lost in a reductionist approaches.
  • Results in complex logical formulations that defy common sense and experience.
    • Fragmentation of experience, failure to look at context, static instead of process.
  • As is evident in many philosophical paradoxes.
    • Things that are contrary to received opinion or expectation, such as:
      • One grain of sand = no heap, incremental grain of sand can never make a heap, etc.
      • Prisoner’s dilemma: the rational person should not act selfish.
• The alternative is a right-brained contextual approach:
  • Things are what they are because they:
    • Find themselves in the surroundings in which they find themselves.
    • Are connected to whatever it is that they are connected to.
  • Understanding is derived from the whole.
    • The whole thing that emerges, within a context.
  • Truth is a process, a relationship between things, approximate, arising out of our engagement with the world.
    • Engagement of the subject with the body, of the body with the world.
      • Embodied understanding of the world, imagination.
    • Experience over conceptual thought.
  • This process, the formation of a relationship is driven by intersubjectivity and empathy:
    • Intersubjectivity: the shared experience, made possible by our embodied existence alongside others.
    • Empathy: to feel what the other is feeling.
• Highlights the importance of the right hemisphere.
  • Needed to introduce us to new things
  • Otherwise we just see what we expect to see (left).
  • Open attention to the world.
• Implications for “truth”.
  • Left: prioritizes the system, regardless of experience = internally coherent.
  • Right: what it learns from external experience (bullshit detector).

Knowledge and the two hemispheres

• Two sequential stages of knowledge:
  • First (right): encounter with the other (betweenness), to be experienced, uncertain, unique.
  • Then (left): putting things together from bits, facts, certainty, fixed repeatable.
• Knowledge relies on distinctions:
  • We can’t experience something unless there is a change or difference.
  • Our senses respond to the differences between values.
• We can only understand the nature of something new by comparison with something old.
  • Similarities, differences.
• What we choose to compare the new thing with, determines which aspects we experience.
  • Each hemisphere has its own “stance”, highlighting different aspects.

Language and the two hemispheres

• Language is distributed across both hemispheres.
  • Left: syntax, vocabulary.
  • Right: meaning, emotional significance.
• Evolved in the hemispheres in the familiar right-left-right order:
  • Right: starts out as embodied expression of emotion (like gestures).
    • Shared by other animals.
  • Left: evolves to grasp and manipulate the world (memory, precision).
    • Shared by other animals.
  • Right: returns to physical world through use of metaphors (comparisons).
    • Not shared by other animals (creativity, humor, etc.)
• Embodied expressions of emotion (right).
  • The urge to communicate (emotion), promoting togetherness.
    • Sharing information, cooperation and collaboration.
    • Makes humans competitive at the group level.
    • Not driven by individual utility alone.
    • Transcending utility, forces of chance and selection.
    • We choose to imitate certain forms of behavior, rather than driven by evolution.
  • Starts with one individual ‘inhabiting’ the body, the emotional world, of another.
    • A skill learnt through imitation (rather than rules).
    • Communication occurs when we feel like what it’s like to be the other person.
  • May be derived from non-verbal language.
    • Language itself is not necessary for communication.
      • Many mental activities don’t require language: planning, categorizing, etc.
    • May have derived from music.
      • Music and language have a shared architecture: phrases, meaning, etc.
      • Music itself is an extension of grooming.
        • Grooming: binding mechanism for individuals in a group.
      • Grooming (right) => music (right) => poetry (right) => prose (left).
  • Grasp and manipulate (left).
    • Embodied expressions get hijacked by the left brain.
      • Speech involves the same brain processes as certain bodily movements (gestures).
      • Utterances made in sync with movements (gestures, tool making, grasping).
    • Memorialization allows for transmission of information about things that are not present.
      • Bringing precision and fixity (naming things, controlling them).
      • Firming up and shaping how we see the world.
      • Selecting which aspects stand out, which ones recede (consistency, restrictive).
    • Self-consistent system of symbols (detached from reality).
• Return to physical world of experience (right).
  • Through use of metaphors, sophisticated emotions.
    • Metaphors: one thing understood in terms of another thing.
    • Felt as sharing a common nature.
  • Links language to life: embodies thought and places it in a living context.
    • Language must come down to a thing experienced, outside the system of signs.
  • Highlights different roles of left and right hemispheres:
    • Left: isolation, manipulation and control (utility).
    • Right: experience and connection (empathy).
• Ground truths:
  • Before harmony, there must be difference.
  • At all levels: coherence and unification versus incoherence and separation.
• Side note:
  • For the left brain to do its language work, it hasn’t grown larger than the right brain.
  • Rather, it has inhibited growth of the right brain…

Other Links:

• EconTalk
• Conversation with Jordan Peterson