Venture capitalist Roger McNamee was an early investor in Facebook and claims he mentored founder Mark Zuckerberg . He still sees value in the platform, but he’s concerned about the growing economic and political power behind Facebook and other social media sites. He shares his concerns in his new book, Zucked: Waking Up to the Facebook Catastrophe . McNamee joined the Knowledge at Wharton radio show on SiriusXM to talk about why he’s speaking out against the company he once championed. (Listen to the podcast at the top of this page). “I became an activist because I was among the first to see a catastrophe unfolding, and my history with the company made me a credible voice,” he wrote in an opinion piece for Time . McNamee is co-founder of Elevation Partners private equity firm and co-founder of the Center for Humane Technology. An edited transcript of the conversation follows.…