This is Robin Hanson (at Overcoming Bias) on how much social scientists know and how little of it makes it to public or political debates.
Social scientists know lots.
As a physics student and computer science researcher, I assimilated the usual "hard science" perception that "social science" is an oxymoron -- no one knows much about it, so your opinion is as good as anyone's. When I finally decided I needed social science credentials, to turn my institution hobby into a career, I focused on experimental economics, the only sort a hard scientist could trust, and Caltech, with impeccable hard science credentials. But I was soon thoroughly convinced: social scientists know tons.
Why then do so many people think otherwise? Many say it is because social scientists are stupid, or the social world is too complex or uncontrollable. Better answers are that social expertize conflicts with our overconfidence about familiar experience, or with our democratic ideology that everyone's political opinions should get equal weight. But the best answer, I think is that most public talk by social experts reflects little social science. That is, what social experts say in legal or congressional testimony, or in newspapers or magazines, mostly reflects what they and we want and expect to hear, instead of what expert evidence reveals.
(…) social scientists have data and theory giving powerful insight into a great many social issues, at least to those with open minds. Open minded social scientists talking privately can make great intellectual progress. But powerful forces are eager to distort the messages social scientists give the public on important topics. Academics with deserved reputations for careful accurate work on obscure academic topics tend to adopt different standards when writing editorials or advising politicians. Even if most academics would not do this, those selected for such roles usually do.
(…) a mechanism that could cut through this fog and tell the public what honest social scientists really think might have great social value, at least if the public could be shamed into listening to them.