The benefits of free trade. The effects of climate change. The protections afforded by vaccination.

These are three areas that are feeling the effects of the long-running war on expertise.

The US Chamber of Commerce, which leans Republican, has been running an advertising campaign to persuade Americans that tariffs are bad but trade is good. The campaign has some facts and figures. And it sticks to principles that are generally agreed by all economic experts. But they’re preaching to the converted. President Donald Trump’s base is probably less likely to trust expert opinion than almost anyone else.

The same is true of climate change and the imperative to vaccinate babies. As polio retreats from the planet and we suffer a less from diseases that once wiped out whole communities, we forget. And we disbelieve those who know enough to remind us.