When people talk about this sort of society, they imagine that it used to work like this in some simpler, better time. But no such era ever existed, as Mike Konczal has written. From the Postal Service to the railroads to breaks for business investment, the government has always been involved in and supportive of private enterprise. America was built on it.

While voluntary charitable organizations doled out most of the social insurance before the New Deal, they constituted a threadbare network that quickly snapped under the pressure of the Great Depression. The same happened during the Great Recession: Private charitable giving from individuals, corporations and foundations fell as the economy faltered; it was the government that stepped in to cushion the worst of the blows.

Privatizing government functions doesn’t work much better. Mr. Ryan has released a number of proposals over the years to get the government out of Medicare and Social Security and push people instead into private markets. But analysis of his Medicare proposal found that people would end up paying more out of their own pockets, while costs would increase because private plans are more expensive. Exposing Social Security to the whims of the stock market could wipe out accounts when it took a serious downturn and would leave individuals to make smart enough investment choices so they had enough to live on in old age. The government, on the other hand, can do things cheaply and equitably.

It’s worth noting that conservatives who urge people to shrink their tax bills are talking to only one group: the well off. There are already many low-income people who don’t pay federal income taxes because they make so little, yet those people have been characterized as “takers,” in the parlance of Mr. Ryan, and were infamously written off by Mr. Romney when he ran for president. It’s a stance Mr. Trump agreed with, arguing that a “large percentage” who don’t pay taxes “feel that they’re entitled.” It’s not smart for them to owe the government nothing; instead, that makes them lazy moochers.

By contrast, the wealthy who reduce their tax bills are simply keeping more of what’s rightfully theirs. But that wrongly assumes that fortunes are built in isolation. Plenty of government resources help make fortunes possible: Taxes finance roads and waterways that transport materials to build factories or goods to stores. Public education produces a work force ready to fill jobs. The court system enforces contracts and cracks down on theft. As Senator Elizabeth Warren, Democrat of Massachusetts, put it in a now-famous video, “There is nobody in this country who got rich on his own.”

Mr. Trump should know that fortunes don’t grow from individual efforts alone. Beyond the multimillion-dollar loan from his father that he insists was “small,” Trump built his New York real estate empire with at least $885 million in tax breaks, subsidies and grants that lowered his costs and increased profits. He himself has noted that some of the buildings he owns wouldn’t have been feasible without government help.