Final answer:
The question concerns the historical shift in Marxist beliefs by an individual named Conze, who began doubting Marxism in the 1930s.
Step-by-step explanation:
The student's question touches on the historical review of the Marxist beliefs of an individual named Conze. It seems that Conze, who was once a staunch supporter of Marxism, began to have doubts about its theoretical foundations in the 1930s. Unfortunately, without more context, it's difficult to provide a detailed explanation of Conze's evolving views. However, instances of former Marxists reconsidering their beliefs are not uncommon in the history of the ideology, particularly as political, economic, and social realities of the 20th century unfolded.