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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Values and beliefs
Why a single tree, uprooted in a typhoon, means so much to one man in Hanoi
7 minutes
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Meaning and the good life
Why Orwell urged his readers to celebrate the spring, cynics be damned
11 minutes
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History
Hags, seductresses, feminist icons – how gender dynamics manifest in witches
13 minutes
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Meaning and the good life
Leading 1950s thinkers on the search for happiness in trying times
29 minutes
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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
4 minutes
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Art
Radical doodles – how ‘exquisite corpse’ games embodied the Surrealist movement
15 minutes