Throughout his 16 years in Congress, he has advocated steadily for profound changes in the way Americans receive help from the government. He has sought to introduce market forces into federal programs, give state authorities more say over how those programs are administered, and force recipients of welfare to submit to careful monitoring by state-appointed caseworkers.

His vision is one of more local control, greater personal responsibility and less tolerance for mistakes on the part of Americans on the margins of the economy.

Ryan has also proposed drastic top-line reductions in federal spending. In 2012, he advocated a 91 percent reduction in all government programs outside of the military and mandatory spending such as Social Security and Medicare. His proposals are not always entirely clear on how he’d achieve these savings, though.

By contrast, he has presented thoroughly developed ideas on structural changes to public programs.

Ryan sponsored legislation in 2005 that would have partially privatized Social Security, allowing Americans to invest some of their payroll taxes in mutual funds and other securities instead of paying into the program’s trust fund.

The initiative to privatize Social Security had both the practical goal of saving money and the philosophical one of expanding personal freedom. Americans would have had more control over their retirement savings, but the reform would also have exposed them to risks.

The proposal failed, and Ryan hasn’t mentioned the idea in any of recent proposals. That’s not to say that he has retreated, though. He is still advocating controversial changes to entitlement programs that are decades old and widely popular.

Specifically, Ryan has proposed partially replacing Medicare with a system of vouchers, which retirees could use to buy health insurance from the provider of their choice. Again, the vouchers would give beneficiaries greater freedom in choosing their doctors and their hospitals. Private firms would have a chance to look for new ways of providing medical care to the elderly at lower cost. Depending on the details of the reform, though, it could also create risks for some recipients, such as those who live in regions where health care is more expensive. This was the proposal that Gingrich was criticizing as too conservative.

As for other public-assistance programs — Medicaid, food stamps, housing vouchers and more — Ryan has proposed giving the money used to administer them over to the states, and allowing local officials to decide how best to use it.

In order to qualify for a state-run program under his plan, recipients would have to meet with caseworkers and agree to specific goals for their personal lives, which they would penalized for failing to fulfill. Ryan’s opponents say this approach misunderstands the nature of poverty (which is as much a result of the failures of the economy and society in general as the failures of individual people) as well as the difficulty of actually being poor. Life in poverty, Ryan’s critics say, is chaotic and unpredictable, and those experiencing it will frequently fail to achieve their goals through no fault of their own.

Maybe this proposal, more than any other, explains Ryan’s reputation for “social engineering.” All of his ideas, though, share a common theme. He would alter the relationship that the vulnerable, the poor and the elderly have with their government in order to allow more Americans to benefit — or to suffer — from their personal choices.