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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Rituals and celebrations
A beginner’s guide to a joyful Persian tradition of spring renewal and rebirth
3 minutes
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Metaphysics
Simple entities in universal harmony – Leibniz’s evocative perspective on reality
4 minutes
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Biography and memoir
The unique life philosophy of Abdi, born in Somalia, living in the Netherlands
29 minutes
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Ethics
For Iris Murdoch, selfishness is a fault that can be solved by reframing the world
6 minutes
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Death
A hunter’s lyrical reflection on the humbling business of being mortal
6 minutes
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Love and friendship
After his son’s terrorist attack, Azdyne seeks healing – and his granddaughter
25 minutes
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Art
More than breathtaking, ‘The Birth of Venus’ signalled an aesthetic revolution
19 minutes
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Values and beliefs
A Zen Buddhist priest voices the deep matters he usually ponders in silence
5 minutes
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Thinkers and theories
‘My art is oratory, Socrates.’ An ancient warning on the power and peril of rhetoric
4 minutes