We tax polluters. Why not tax spreaders of misinformation?

Trust is the glue that holds society together and makes cooperation possible. But research shows that Americans’ faith in institutions and in each other has cratered in recent decades, driven in part by the rampant spread of misinformation and partisan division.

In economic terms, this growing mistrust is a social tax that makes everything we do more costly, from business transactions and elections to interactions with colleagues and neighbors. It creates additional friction in every encounter with a stranger...