Jonathan Zittrain is concerned about Facebook’s ability to swing elections:
All sorts of factors contribute to what Facebook or Twitter present in a feed, or what Google or Bing show us in search results. Our expectation is that those intermediaries will provide open conduits to others’ content and that the variables in their processes just help yield the information we find most relevant. (In that spirit, we expect that advertiser-sponsored links and posts will be clearly labeled so as to make them easy to distinguish from the regular ones.) Digital gerrymandering occurs when a site instead distributes information in a manner that serves its own ideological agenda. This is possible on any service that personalizes what users see or the order in which they see it, and it’s increasingly easy to effect.
There are plenty of reasons to regard digital gerrymandering as such a toxic exercise that no right-thinking company would attempt it. But none of these businesses actually promises neutrality in its proprietary algorithms, whatever that would mean in practical terms.