Philosopher Dan Dennett makes a compelling argument that not only don’t we understand our own consciousness, but that half the time our brains are actively fooling us.

Dan Dennett argues that human consciousness and free will are the result of physical processes. His 2003 book “Freedom Evolves” explores how our brains evolved to give us — and only us — the kind of freedom that matters, while 2006’s “Breaking the Spell” examines belief through the lens of biology. Full bio on TED.com»

If you don’t have 50 minutes, watch him on TED.