He's taking on LeBron over whether the government does or should mainly provide public goods. He has somehow grokked that public goods are non-rival (my consumption doesn't reduce the amount available for you to consume) and non-excludable (you can use the good whether you pay for it or not). As I pointed out earlier, national defense is pretty close to a pure public good.
In the real world, things are not so simple, as some goods may be conditionally rivalrous and excludable (James Buchanan called these "club goods") and some goods are forced to be non-excludable by force of law.
M.S. says the following:
Roads are rival and excludable. Unemployment insurance is rival and excludable. Health insurance for seniors is rival and excludable. Primary education is rival and excludable. Police protection is rival and excludable. Art museums and history museums are rival and excludable. Swimming pools, parks and zoos are rival and excludable.
Well, roads are conditionally rival and generally non-excludable by dint of government policy. That is, the government levies taxes, builds roads and anyone can drive on them without paying a fee (turnpikes and private toll roads are few and far between in this country).
Same goes for primary education. I don't see how one can claim that primary education in the US is excludable. It could be excludable, but government policy has made it non-excludable.
In theory, police protection is close to a pure public good in the area where the police have jursidiction. Now it's true that if a cop is at my house, there's one less cop around to go elsewhere, but the "law and order" brought by a police force is non-rival. And, at least in theory, police don't charge victims of crimes for their services. Anyone can have the police come and fill out an accident report.
Anyone making the statements M.S. made on an exam in an undergrad public econ course would be getting an F.
Then comes the funny fail part of the post. After the rant about how roads, parks, and museums are "rival and excludable", i.e. NOT public goods, MS concludes as follows:
So, then we have the second claim, that with public goods, adding extra people to the mix with no spending boost is compatible with those additional people getting more or less the same services as the previous consumers. I think my objection to this is best illustrated with a few pictures.
And people, can you guess what he shows pictures of? A road, a beach, and a museum!
In other words, the very things he just got done vociferously claiming were NOT public goods!