Fact Versus Opinion: Finding the Thesis of a Passage - MCAT
I think a lot of what this test looks for is the ability to separate fact and opinion. That’s why you get questions like "does it strengthen or weaken this statement to say…?" and so forth. So when evaluating each assertion, you need to look past the facts, which contribute to the summary, but are not the point of the passage. It is the conclusions derived from those facts–which are opinions that the author seeks to support by the facts–that are the main idea.
View all authors as attempting not to inform you, but to pursuade you. What conclusion are they trying to make you draw from the data? Are there any conceivable ways in which the data might be construed to mean something else? Even if you know nothing about the subject, can you imagine a person disagreeing with the conclusions?
When they ask you "what’s the main idea?" the answer is not likely to be the pure informational themes that they give, like "many painters in the 18th century worked with one another." That’s just informational–it sounds like that’s just a trend demonstrated by the anecdotal evidence that might be presented. More interesting as an idea is that, say, they were not appreciated in their time, or that European painters were more appreciated in the US than at home, or so forth. There’s a subjective quality to these sorts of assertions, and to back this up, one would likely give a series of anecdotes. Don’t just try to identify what the anecdotal information has in common; try to seek why it is relevant. Try to find the assertion which would be constroversial or unexpected if the anecdotes weren’t there.
Apart from that, there are situations with those sorts of questions where every answer choice is an opinion. In these instances, you want to be sure that you find something that applies to every (or almost every) paragraph, rather than applying to only one paragraph. If the selection applies to only one example given, it is not the theme.
The final pitfall is the qualifiers seen at the beginning of the article. Sometimes you have a choice which refers to a statement made in the opening paragraph that is not the thesis itself. Generally, such a claim, made at the outset, is made to justify the course of reasoning that will proceed. It is common for people that are seeking to pursuade that they first try to justify why you should read the article, or to dispel a common conception that impedes their ability to teach you something new. These statements are not theses.
*In short, look for the theme/thesis/main idea as an *opinion* that acts as a recurrent theme throughout, and that the supporting evidence would act to support in all or most all instances.*
