Download a free audiobook version of “The Sandman“ and support TED-Ed's nonprofit mission: https://www.audible.com/ted-ed -- Bizarre things happen in dreams: you fly, or conjure an all-you-can-eat buffet out of thin air, or get chased by witches through the halls of your school. But the strange things that happen in dreams don’t seem strange at the time. So, how do you know you’re not in a dream right now? Is there a way to prove that you're awake? Daniel Gregory digs into the philosophical theories of wakefulness. Lesson by Daniel Gregory, directed by Daniel Stankler. Support Our Non-Profit Mission ---------------------------------------------- Support us on Patreon: http://bit.ly/TEDEdPatreon Check out our merch: http://bit.ly/TEDEDShop ---------------------------------------------- Connect With Us ---------------------------------------------- Sign up for our newsletter: http://bit.ly/TEDEdNewsletter Follow us on Facebook: http://bit.ly/TEDEdFacebook Find us on Twitter: http://bit.ly/TEDEdTwitter Peep us on Instagram: http://bit.ly/TEDEdInstagram ---------------------------------------------- Keep Learning ---------------------------------------------- View full lesson: https://ed.ted.com/lessons/how-do-you-know-you-re-not-dreaming-daniel-gregory Dig deeper with additional resources: https://ed.ted.com/lessons/how-do-you-know-you-re-not-dreaming-daniel-gregory#digdeeper Check out our full book recommendation: https://shop.ed.ted.com/collections/ted-ed-book-recommendations/products/the-sandman Animator's website: http://danstan.co.uk/ ---------------------------------------------- Thank you so much to our patrons for your support! Without you this video would not be possible! Lex Azevedo, Noa Shore, Michael Aquilina, Jason A Saslow, Dawn Jordan, Prasanth Mathialagan, Samuel Doerle, David Rosario, Dominik Kugelmann - they-them, Siamak H, Ryohky Araya, Mayank Kaul, Christophe Dessalles, Heather Slater, Sandra Tersluisen, Zhexi Shan, Bárbara Nazaré, Andrea Feliz, Victor E Karhel, Sydney Evans, Latora Slydell, Noel Situ, emily lam, Sid, Kent Logan, Alexandra Panzer, John Hellmann, Poompak Meephian, Chuck Wofford, Daniel Erickson, frank goto, Jayson Hauschild, J D Wallace, Marq Short, Chen Jun Xiang, Adam Pagan, Paul Schultz, Behzad Farhanieh, Anders Sørheim, Wes Winn, Conder Shou, BrushReads, Matt Kennedy, Jonah Dobbs, ntiger, Noname, Hansan Hu, Cameron Burkle, Dhanwanth Varadhan, David D and Zuko Gameplays.