Final answer:
During the 1950s, internal conflicts within the Democratic Party led to the emergence of the States' Rights Democratic Party (Dixiecrats) as Southern Democrats opposed federal civil rights measures. This factional shift contributed to many Southern Democrats later joining the Republican Party, while other Democrats supported progressive social welfare and civil rights reforms, creating a diverse and pluralistic conception within the party.
Step-by-step explanation:
The query about who opted in the 1950s for a 'strident but pluralistic conception of Democratic socialism' refers to the complex changes and factional realignments within the Democratic Party in the United States during that era. The post-World War II period witnessed significant shifts in political ideologies and alliances. In the 1930s and 1940s, the Democratic alliance was strong, supporting economic measures to aid farmers and the unemployed, largely under the New Deal Coalition. However, as the 1950s approached, the party faced internal conflicts, especially over social issues like civil rights. Southern Democrats broke away from the party, coinciding with figures such as Strom Thurmond who rallied against federal civil rights measures, preferring states' rights and smaller government, which led to the formation of the States' Rights Democratic Party (Dixiecrats).
In contrast, other Democrats sought to support civil rights and social welfare reforms, setting the stage for later figures who would embrace a more progressive agenda. By the 1960s and 1970s, many Southern Democrats shifted their allegiance to the Republican Party. The term 'strident but pluralistic conception of Democratic socialism' likely refers to the Democratic faction that advocated for more robust social welfare, anti-segregation, and economic reform, but this is a retrospective analysis as the term 'Democratic socialism' was not widely used or conceptualized in the same way during the 1950s as it is today when associated with figures like Bernie Sanders and Alexandria Ocasio-Cortez.