LSAT Question Explanation
PT 105, Section 1, Question 21
Necessary AssumptionArgument structure
The two doctrines are mistaken.
Doctrine 1: Economics must factor into the explanation of every historical event Doctrine 2: Attempts to explain all historical events psychologically
There have been events that were due both to economics and the early childhood experiences of major participants.
Explanation
The flaw here is that the author is trying to disprove the two doctrines on the basis that some events had economic and psychological factors. But the doctrines don't seem to say that they're trying to explain history exclusively through an economic or psychological lens. Just that those subjects factor in to all explanations.
So the author seems to be assuming that doctrine 1 demands that we only consider economics, and doctrine 2 demands that we only consider psychology.
Answer choices
This addresses the assumption the author made in the argument. The fact that some historical events have both economic and psychological explanations doesn't disprove doctrine 1... unless we assume that doctrine 1 only allows the consideration of economic factors.
The second doctrine seeks to explain things psychologically, and it says especially through childhood experiences. But it doesn't say only childhood experiences. Other psychological factors could be important and the conclusion would still hold.
The author says that because both factors help explain some events the doctrines are wrong. It doesn't matter if the factors influenced the events an equal amount, just that they both apply at all.
This isn't necessary. The author uses as evidence that some events could be explained by both factors. We don't need to know that it's likely that both factors have been used in attempts to explain an event.
The author's evidence is that some events were influenced by both factors. We don't need to know that all events were.