Afterward, only Facebook itself is interested in the legal minutiae of what permissions it gave to which developers. As far as everyone else is concerned, it doesn’t matter whether an app gets the data for research purposes or for straight-up political ones. Average users worry more about convenience than privacy.
The relevant question, however, is what a campaign can actually do with the data. CA’s supposedly sinister skill is that it can use the Facebook profile information to build psychological profiles that reveal a person’s propensity to vote for a certain party or candidate. When matched against electoral registers, targeted appeals are possible.
But no one should take the psychological profile stuff at face value. No academic work exists to link personality traits, especially those gleaned from the sketchy and often false information on Facebook profiles, definitively to political choices. There is, however, research showing that values or even genetic factors trump traits. It’s not even clear how traits affect political behavior, such as the tendency to vote and donate to campaigns: Some researchers, for example, have found a negative relationship between emotional stability and these measures; others have found a positive one.