Knowing what separates wakeful reality from dream states seems rather simple on its surface. After all, even if a dream feels quite real in the moment, it’s unbound from continuity and the natural laws of our (presumed) waking lives. Yet proving that you’re awake, rather than just intuiting it, has been a perilous task for philosophers across the centuries. Beginning with the ancient Chinese philosopher Zhuang Zhou’s famed butterfly dream, this TED-Ed animation tackles how thinkers from Al-Ghazali in medieval Persia, to René Descartes and Thomas Hobbes in 17th-century France and England, to neuroscientists today have approached the question of whether we can ever truly know we’re awake.
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Virtues and vices
Why Bennie tried to disappear, and what happened when he was found decades later
16 minutes
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Art
Background music was the radical invention of a trailblazing composer
17 minutes
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Metaphysics
What do past, present and future mean to a philosopher of time?
55 minutes
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Spirituality
Through rituals of prayer, a monk cultivates a quietly radical concept of freedom
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Art
Radical doodles – how ‘exquisite corpse’ games embodied the Surrealist movement
15 minutes
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Ethics
Plato saw little value in privacy. How do his ideas hold up in the information age?
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Animals and humans
Are zoos and natural history museums born of a desire to understand, or to control?
57 minutes
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Virtues and vices
Why Jean-Jacques Rousseau and Adam Smith were divided on the virtues of vanity
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Beauty and aesthetics
In art, the sublime is a feedback loop, evolving with whatever’s next to threaten us
9 minutes