Have any noted "free market, deregulation" advocates changed their tune?

[erislover]

That is half of it. The other half of externalities are positive externalities, where the benefits are not directly reaped by the parties involved. Negative externalities mean a good is overproduced (because the costs aren’t accounted for directly) while positive externalities are underproduced (because the benefits aren’t directly realized).

Positive externalities means a good would be underproduced. Sorry.