Two doctrines have been greatly influential in this century. The first holds that the explanation of any historical event must appeal to economic factors. The second attempts to account psychologically for all historical events, especially in terms of early childhood experience. Both doctrines, however, are mistaken. Certainly there have been events that the early childhood experiences of the major participants in the event.
What this question is testing
Your task
Find the assumption the argument requires in order for its conclusion to hold.
Common trap
Answers that would help the argument but aren't strictly required (sufficient, not necessary).
Winning move
Negate each choice — the right one breaks the argument when negated.
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