Final answer:
The statement that idealism in the Third World gave way to dictatorship and authoritarian rule by the end of the 1960s is true. Numerous factors, including military influence and Cold War dynamics, contributed to this shift from initial democratic aspirations to authoritarian governance in various countries.
Step-by-step explanation:
By the end of the 1960s, idealism in the Third World had indeed begun to give way to dictatorship and other forms of authoritarian rule. This statement is true. After the initial post-colonial period, which saw many new states adopt democratic constitutions, various factors led to the establishment of authoritarian regimes.
Often, the military, which was trained by colonial powers, felt that they were better suited to governing than the existing democratic institutions, particularly in times of economic or political turmoil. This transition was further complicated by the Cold War, as Western powers at times supported repressive dictatorships out of fear of communism.