How did Cold War politics and assumptions shape American foreign policy from 1950–1980?
Cold War politics and assumptions shaped the foreign policy of the United States in many ways during the time period that you mention here. Let us look at a few of the ways in which this happened.
They caused the US to intervene in many places because it believed those interventions were necessary to prevent the spread of communism. The Vietnam War is the most famous example of this, but there were many others. Because the US assumed that the Soviet Union was trying to spread communism around the world, it reacted in this way.
They caused the US to support morally questionable non-communist regimes. Because the US was worried about the spread of communism, it gave a great deal of support to regimes that were not very democratic and which did not care much about human rights. South Africa’s apartheid regime is one of the best examples of this.
They caused the US to try to strengthen other countries’ economies. After World War II, for example, the US helped both Germany and Japan to rebuild their economies. These countries eventually became major competitors of the US.
Cold War assumptions about the spread of communism led to all of these types of foreign policies.