[astalwick]

It's not about removing human agency. It's about nudging the aggregate views of a whole population, ever so slightly. Determine what works, reinforce that, repeat algorithmically.

He's making the point that Facebook has the ability to apply machine-learning-like reinforcement algorithms to whole populations.

You or I, individually, still have agency. Large populations have inertia - they're slow to move - but I'm not sure they have real defense against this kind of manipulation. I guess the real defense here is a diversity of sources (but we all know people who get all of their news from [fox | cnn | facebook | whatever]).