Split brains reveal a bizarre feature of consciousness | Sam Harris, Roger Penrose, Sophie Scott

Episode Overview

• The discussion explores the nature of the self, questioning whether it is a real, continuous entity or an illusion constructed by the brain.
• Neuroscientist Sam Harris argues that while consciousness is the one undeniable reality, the feeling of a stable "self" at the center of experience is an illusion.
• Nobel laureate Roger Penrose links the concept of self to the continuity of consciousness and memory, raising questions about what happens to the self in cases like split-brain patients.
• Cognitive neuroscientist Sophie Scott provides a biological perspective, highlighting that while most of the body's cells are replaced, our neurons remain, providing a physical basis for a continuous self shaped by memory and social context.

Key Concepts

• The Illusion of Self: The central argument that the common feeling of being a static, unchanging subject or "I" at the center of one's experience is not a fundamental reality but a cognitive construct or an illusion.
• Consciousness vs. Self: A distinction is made between consciousness (the raw, undeniable fact that experience is happening) and the self (the feeling of being the one to whom the experience is happening). Consciousness cannot be an illusion, but the self can be.
• Subject-Object Duality: The typical experience of being a subject observing the objects of consciousness (sights, sounds, thoughts) is described as the core of the illusory self. This duality can dissolve through introspection or meditation.
• Split-Brain Thought Experiment: The case of patients whose brain hemispheres are surgically separated is used to question the unity of the self. If the brain is divided, does the self also divide, creating two separate people in one body?
• Biological Continuity: The self is tied to the physical brain. Unlike most other cells in the body which are replaced over time, a person's neurons are with them for life, providing a basis for continuous identity and memory storage.
• Social Selves: Our sense of self is not monolithic; it changes depending on the social context. We behave and feel like different "people" when interacting with a parent, a police officer, or a friend, suggesting the self is dynamic and relational.

Quotes

• At 00:27 - "And that seeming is the fact of consciousness." - Sam Harris explains that consciousness is the fundamental reality that cannot be an illusion, because the very appearance of an illusion is itself an instance of consciousness.
• At 04:14 - "I mean, I regard the question of self as all tied up intimately with the issue of consciousness." - Roger Penrose frames his perspective, emphasizing that the two concepts cannot be easily separated and that understanding one requires understanding the other.
• At 09:42 - "On the course of every 10 years or so, you get a completely new body, except for the hair cells in your ears, the lens, cells of your crystalline lens in your eyes, your egg cells if you're female, and your neurons." - Sophie Scott highlights the unique biological continuity of the brain, suggesting it is the physical foundation for a stable sense of self over a lifetime.

Takeaways

• Practice introspection to investigate your "self". Pay close attention to your moment-to-moment experience and try to locate the fixed, unchanging "I" that feels like it's in control. You may find that this sense of self is just another appearance in consciousness, like a thought or a feeling, rather than a permanent entity.
• Separate the fact of experience from the story of "you". Recognize that while the content of your thoughts and the narrative of who you are may be complex and even illusory, the underlying capacity for experience (consciousness) is fundamental and real. This distinction can help reframe your relationship with your own thoughts and identity.
• Acknowledge the role of memory and context in shaping who you are. Your sense of a continuous self is heavily dependent on your memories, which are physically stored in a brain that remains with you for life. At the same time, this self is fluid and adapts to different social situations, showing that identity is both biologically grounded and socially constructed.