The argument is that the “advance of the perihelion of Mercury” shouldn't be considered evidence that supports Einstein's theory because the “advance” existed when Einstein was developing his theory and because there is the possibility that Einstein rigged his theory to fit the perihelion advance. If I were to paraphrase that into an “if/then” statement, then it would look something like this: if it existed during development of Einstein's theory, or if there is a possibility that Einstein rigged his theory to fit it, then it shouldn't be counted as evidence for Einstein's theory.
The question stem is asking me to find a principle that will strengthen the flimsy argument above. In short, I'm going to look for some variation of my “if/then” statement.
A. Nope. This is definitely not it. Who said anything about the theory being credited? We're talking about whether something can be used as evidence to support the theory; we're not talking about what can be credited. A is gone because doesn't come close to looking like my “if/then” statement.
B. This goes against the argument above. In other words, it doesn't strengthen the argument. B is gone.
C. Man, the answer choices are continuing to look ugly! This one is wrong too. We're not talking about degrees of support (i.e., well supported or not well supported). The argument is concerned with support, period. Should it be counted as support or should it not? Answer choice C doesn't strengthen the argument.
D. I like this one. It resembles my “if/then” statement. I'm going to keep it.
E. This one's tricky. It uses alluring key words and signals. But we're not talking about whether the theory should be counted as predicting the “advance,” we're talking about whether the “advance” should be counted as evidence for the theory. E is a goner as well.
Our answer is is D.
From Dave: I'm the founder of LSAT Sensei, a boutique LSAT prep and tutoring company based in Chicago. I received my JD from the University of Chicago Law School, and I've been teaching the LSAT for a decade (and counting). I took the LSAT three times: 163, 174, and 180. I had to work my tail off to improve my LSAT score, so I completely embrace the the philosophy that succeeding on the LSAT is a journey. You can tweet me here.
I love how even after wrestling with it for ten years, the LSAT is still fun and intriguing. Back when I was studying to get into law school, my favorite thing about the LSAT was the Games (analytical reasoning) section. I was a natural at it, and I totally got huge ego boosts when I could crush the entire section in 15 minutes or less. But over the years, my favorite thing about the LSAT constantly changes - currently, I get a huge kick out of tearing apart the Logical Reasoning prompts/stimuli. The LSAT authors have a way of digging their own grave.
Please ask questions and/or suggest corrections to anything that seems confusing... we want to make this the best resource we can for LSAT students. We'll have all the June 2013 explanations up as quickly as possible. Thanks for reading. Tell your friends! --nathan