In the early days of digital culture, Jaron Lanier helped craft a vision for the internet as public commons where humanity could share its knowledge - but even then, this vision was haunted by the dark side of how it could turn out: with personal devices that control our lives, monitor our data and feed us stimuli. (Sound familiar?) In this visionary talk, Lanier reflects on a "globally tragic, astoundingly ridiculous mistake" companies like Google and Facebook made at the foundation of digital culture - and how we can undo it.