Chris Hayes inveighs against the economically silly argument that immigrants do jobs Americans don’t want:

I don’t want to buy a slice of pizza for $45. It doesn’t mean I don’t like pizza! I’m not particularly interested in writing a book for the total payment of $9. It doesn’t mean I don’t want to write a book!

Raise. The. Wages. You’ll find plenty of workers. I promise.

But then Megan McArdle correctly reformulates the argument:

It does no good to say that American workers would be happy to gut chickens, or clean houses, or landscape your yard, for $20 an hour, if other Americans cannot afford to purchase those services at that price. If we had no illegals, some Americans would undoubtedly get their jobs at higher wages. Other jobs, such as fruit picking, would probably be automated. Meanwhile, many Americans would have to go without the services that illegals currently provide, such as landscaping, construction, and home care.

In short, as always in economics, you find the inefficiency by pinpointing the the deadweight loss – the services that would have been purchased in a free market, but aren’t purchased given immigration restrictions.