In his TED Talk, Bostrom's solution to the alignment problem is to build in at the ground level the goal of predicting what we will approve of so that no matter what other goals it's given (cure cancer, colonize Mars, ...), it will aim to achieve those goals only in ways that align with our values. (I see some challenges: One is Who exactly is the WE? Another is the fact that humans can approve of some horrendous things including, under certain conditions, their own subjugation.)

Is there any place where I can find objections/challenges to Bostrom's proposal? Particularly, what do Yudkowsky and others with his outlook say about it? I can make guesses based on what Yudkowsky says, but so far, I've found no explicit mention by Yudkowsky of Bostrom's solution. Generally, where should I go to find any objections to or evaluations of Bostrom's solution?