The new deal changed american political thinking because it was based on the principle that the

federal government should try to solve social and economic problems.

Explanation:

During the Great Depression of 1930's, US President Franklin D. Roosevelt introduced a landmark bill to restore the economic and social conditions of the country. This bill was known as the New Deal and it contained a series of federal government led initiatives, projects, economic and financial reforms.

It placed importance on the government's role in the economic revival of the country. Thus, the New Deal changed American political thinking because it was based on the principle that the federal government should try to solve social and economic problems.