Folks on the left have been getting more interested in science lately (though history tells us that might be something to worry about). They’re right to celebrate the incredible results of scientific progress–but scientific victory isn’t uniform across disciplines.

In some areas (including just about all areas on the cutting edge), scientists disagree with one another.It’s a big, complex world we live in, and we don’t understand it fully. That disagreement doesn’t mean we should discount science entirely, but it does mean we should be careful with it.

Imagine a world where engineers disagreed about the capabilities of their techniques and the strength of the materials they use. Some might be beholden to special interests (which gives me an idea for a public choice version of the Three Little Pigs), others might be dogmatic/superstitious. But even without concerns of systemic issues, we should be hesitant to try to get to the moon. That disagreement should tell us that we aren’t certain enough in our knowledge to make anyone but volunteers put their lives in the hands of those engineers.

Social scientist in particular frequently disagree with each other. Most are trying earnestly to apply the scientific way of thinking to understanding the social world, and it’s worth considering their view points. But applying that knowledge should only be done in a decentralized way. Applying the incredible insights of behavioral economics from the top down is appealing, but it’s probably best to do it piecemeal.

Social engineering and social science are harder than physical engineering and the physical sciences. Part of the problem Western governments face is that they’re trying to engage in social engineering. And politicians are promising them greater degrees of social engineering to improve the well-being of their constituents.

The trouble is two-fold: 1) those social engineering techniques aren’t good enough, even if they’re sometimes appealing. 2) The cost to decision makers of buying snake oil is too low in voting booths.

To my friends who are looking to the government to make things better: whether your hope is for government to help people be better versions of themselves, or to stop bad guys, we should push as much of that policy to the local level as possible. It might be nice if the whole country were more like Berkeley or Salt Lake City, but trying to make it happen at the national level is a recipe for conflict, disorder, and doing more harm than good. Keep policy local.