It should be relatively easy to detect bias if Facebook is open with their algorithm.

Facebook has conducted research on how even small changes to the overall system can materially affect the mood and how that mood was contagious to a given subject's social network. (“Experimental Evidence of Massive-Scale Emotional Contagion through Social Networks”)

The public was disturbed. The university partner in all of this had put out a press-release saying that it passed their ethics board only because the University researchers themselves weren't doing it directly but, merely helped design the experiment.

This says that Facebook has people on staff that have been conducting this sort of thing at scale since 2012. They have no one to answer to. They have everything to gain. If they stay secret, they have nothing to lose.

An individual has no way to detect this because like the proverbial frog in lukewarm water slowly brought to a boil, the filtering on our social network never was so alarming that we jumped out en-masse.

Now Zuckerberg and company could be listening in and manipulating the social discourse of almost all of the free world. We wouldn't know.

People highly suspect that Twitter has a leftist agenda with pushing certain speech and suppressing other speech. Even if you completely agree with Twitter or Facebook's political stance, it should disturb you.

It's like getting on a soapbox in the town square and the air only carrying certain ideas to the town people's ears and refusing to vibrate for others but, you hear all of them just as loud. Over time you'd think that people just aren't responsive to your ideas, get down off your soap box and go home, thinking that democracy was done and that people just didn't like your ideas.

So, Facebook has the means, has the technology, has the research to know how effective it is, has had practice in (publicly) as far back as 2012.

The question isn't if they are going to manipulate the 2016 election, the question is how and to what degree. Even if they deny it, there's really no outside body to know at this point without any inside information.

Granted, Google also has this power to a certain degree and bears responsibility for demonstrating that they aren't manipulating politics. Google has more transparency and their products are to the end of being the library of the world.

Facebook manipulates the messages sent between friends and family. They step into trust relationships. There is a world of difference between the politics of a site on the internet as a search result and an impassioned plea by one of my friends or a family member. The idea that Facebook would suppress those ideas from me is the most disgusting, despicable and detestable thing I can think of. I hold Facebook to a much, much higher standard than Google. Their transparency is much, much poorer.

Ultimately, Google indexes the open internet and I can test their results against other search engines and research projects. Facebook owns both the network and messages. It is impossible for an outside party to verify anything that Facebook says about this at this point. We know that what they do can be significant; that they have researched how effective it can be since 2012.

I don't think it's overly cautious nor paranoid to ask them for transparency on this.