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  • Look at your hand.

  • How do you know it's really yours?

  • It seems obvious, unless you've experienced the rubber hand illusion.

  • In this experiment, a dummy hand is placed in front of you

  • and your real hand is hidden behind a screen.

  • Both are simultaneously stroked with a paint brush.

  • No matter how much you remind yourself the dummy hand isn't yours,

  • you eventually start to feel like it is,

  • and inevitably flinch when it's threatened with a knife.

  • That may just be a temporary trick, but it speaks to a larger truth:

  • our bodies, the physical, biological parts of us,

  • and our minds, the thinking, conscious aspects,

  • have a complicated, tangled relationship.

  • Which one primarily defines you or your self?

  • Are you a physical body that only experiences thoughts and emotions

  • as a result of biochemical interactions in the brain?

  • That would be a body with a mind.

  • Or is there some non-physical part of you that's pulling the strings

  • but could live outside of your biological body?

  • That would be a mind with a body.

  • That takes us to an old question

  • of whether the body and mind are two separate things.

  • In a famous thought experiment,

  • 16th-century philosopher René Descartes pointed out

  • that even if all our physical sensations were just a hallucinatory dream,

  • our mind and thoughts would still be there.

  • That, for him, was the ultimate proof of our existence.

  • And it led him to conclude that

  • the conscious mind is something separate from the material body

  • that forms the core of our identity.

  • The notion of a non-physical consciousness

  • echoes the belief of many religions in an immaterial soul

  • for which the body is only a temporary shell.

  • If we accept this, another problem emerges.

  • How can a non-physical mind have any interaction with the physical body?

  • If the mind has no shape, weight, or motion,

  • how can it move your muscles?

  • Or if we assume it can, why can your mind only move your body and not others?

  • Some thinkers have found creative ways to get around this dilemma.

  • For example, the French priest and philosopher Nicolas Malebranche

  • claimed that when we think about reaching for a fork,

  • it's actually god who moves our hand.

  • Another priest philosopher named George Berkeley

  • concluded that the material world is an illusion,

  • existing only as mental perceptions.

  • This question of mind versus body isn't just the domain of philosophers.

  • With the development of psychology and neuroscience,

  • scientists have weighed in, as well.

  • Many modern scientists reject the idea

  • that there's any distinction between the mind and body.

  • Neuroscience suggests that our bodies, along with their physical senses,

  • are deeply integrated with the activity in our brains

  • to form what we call consciousness.

  • From the day we're born,

  • our mental development is formed through our body's interaction

  • with the external world.

  • Every sight, sound, and touch create new maps and representations in the brain

  • that eventually become responsible for regulating our experience of self.

  • And we have other senses, besides the typical five,

  • such as the sense of balance

  • and a sense of the relative location of our body parts.

  • The rubber hand illusion, and similar virtual reality experiments,

  • show that our senses can easily mislead us in our judgment of self.

  • They also suggest that our bodies and external sensations

  • are inseparable from our subjective consciousness.

  • If this is true, then perhaps Descartes' experiment was mistaken from the start.

  • After all, if we close our eyes in a silent room,

  • the feeling of having a body isn't something we can just imagine away.

  • This question of mind and body becomes particularly interesting

  • at a time when we're considering future technologies,

  • such as neural prosthetics and wearable robots

  • that could become extended parts of our bodies.

  • Or the slightly more radical idea of mind uploading,

  • which dangles the possibility of immortal life without a body

  • by transferring a human consciousness into a computer.

  • If the body is deeply mapped in the brain,

  • then by extending our sense of self to new wearable devices,

  • our brains may eventually adapt to a restructured version

  • with new sensory representations.

  • Or perhaps uploading our consciousness into a computer might not even be possible

  • unless we can also simulate a body capable of delivering physical sensations.

  • The idea that our bodies are part of our consciousness and vice versa

  • also isn't new.

  • It's found extensively in Buddhist thought,

  • as well as the writings of philosophers from Heidegger to Aristotle.

  • But for now, we're still left with the open question

  • of what exactly our self is.

  • Are we a mind equipped with a physical body as Descartes suggested?

  • Or a complex organism that's gained consciousness

  • over millions of years of evolution

  • thanks to a bigger brain and more neurons than our distant ancestors?

  • Or something else entirely that no one's yet dreamt up?

Look at your hand.

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B1 US TED-Ed body mind physical consciousness descartes

【TED-Ed】Are you a body with a mind or a mind with a body? - Maryam Alimardani

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    April Lu posted on 2017/10/03
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