List the strengths and weaknesses of our social security policy. Does it help explain the evolution of social welfare policy in the US? Why or why not?

In the United States, social security was signed into law in 1935 to provide a backstop against certain predictable and unpredictable life events, including old age, death, and disability. The most common element of social security is the Retirement Insurance Benefits (RIB) program, which provides a basic income for persons above a certain age.
The basic income aspect of RIB is one of its strengths. It is both guaranteed and progressive, meaning it increases with the cost of inflation. Because these increases are built into the system, the guarantee of a certain standard of income cannot easily be politicized, in comparison to some countries where increases in benefit amounts require special statutory authorization.
At the same time, however, RIB is not intended to be a complete replacement of income for work-derived sources among elderly Americans. Rather, it is intended to be a backstop only, a way to guarantee a minimum standard of living that is designed to be supplemented by personal savings or investments.
The nature of this duality has informed the evolution of welfare spending in the United States more generally. Taking its cue from social security, American welfare spending tends to be designed to provide basic levels of sustenance in response to emergent events. This is in contrast to other systems, such as Sweden's, which operates on the principal of "welfare for everyone," that is, enrolling the bulk of the population in welfare programs regardless of any emergent factors. For instance, that country's Barnbidrag program makes payments to parents of all children until they reach their majority.