#23 - Main Point

[avengingangel]

Why is B incorrect? Seems more accurate than D. The passage was talking about a rejection of a once widely-believed theory, and how it led to new discoveries, etc. I didn't choose D because it sad "evolution," which I thought was a mischaracterization, and that "rejection" was more appropriate here, as to the purpose of the passage. Thanks.

[James Finch]

Hi AA,

Answer choice (B) breaks down in its description of the passage as "summarizing the reasons for the rejection of an established theory," in that while the summary of reasons aspect is plausible, we are not given any indication of a rejection of an established theory, but rather a modification of it, as the old theory leads to new ones.

Comparing (B) with (D), the word "describes" serves as a better description than "summarizes" for the level of detail and structure the passage gives to the scientific breakthroughs, and the idea of an "evolution of theories" is more clearly supported, especially in the last sentence of the passage, than a wholesale "rejection."

Hope this helps clarify things.

[dbrowning]

Would Planck's theory and classical wave theory be what support the use of the plural "theories" in answer choice D? I eliminated D because I thought of Planck's idea as a hypothesis, which would leave only one theory singular.

[James Finch]

Hi D.,

Yes, Planck's ideas were in direct opposition to wave theory, and while he is only said to have contributed a "hypothesis," Einstein's particle theory, a fleshed-out version of Planck's hypothesis, is brought in the final paragraph, so the passage is dealing with two discrete theories: wave theory and particle theory.

Hope this clears things up!

[Agent00729]

I was deciding between C and D, but ruled out D because I thought "a critical stage" implied one instance of change, whereas the passage seemed to imply it wasn't merely one stage, but a sequence of many events that led to the new understanding. Is the stage they're referring to the Planck contributions? Or did everything occur at the same time in one stage? To me, it seemed like several critical stages occurred, not just one.

[Rachael Wilkenfeld]

Hi Agent,

This passage is talking about a critical stage in the study of radiation. We know it wasn't several long stages, because the author notes at the end how amazing it was that the new theories were fleshed out and developed in only a few years. It's also describing only one major change. Wave theory didn't adequately explain the data with regards to thermal radiation, Plank suggested a possible explanation, and Einstein provided theoretical justification for that explanation. There aren't multiple areas of discovery, or the progression of many different stages of learning about radiation. The passage is like a snapshot of a single new concept.

Hope that helps!

[Agent00729]

That helps, thanks!

[Tajadas]

I don't understand why D is correct. D says "evolution of theories". One of these theories is Einstein's particle theory. What is the other one? I don't think it can be Plank's hypothesis because Plank's hypothesis lacked a theoretical explanation. I don't think it's classical wave theory, because classical wave theory didn't "evolve" so much as it was replaced by particle theory, given Plank's hypothesis and then Einstein's theoretical explanation.

[Adam Tyson]

The evolution referred to in answer D has to be thought of in the full context of the answer, Tajadas. It's the evolution of theories "concerning the nature of a physical phenomenon." That phenomenon is radiation, and the theories that attempt to explain it are wave theory, Plank's hypothesis, and finally Einstein's (and others') theory to justify Plank's hypothesis. It's not about the evolution of a single theory, but is about the evolution of different theories to explain a single type of phenomenon.

That's a pretty common evolution in LSAT RC passages - first there is a theory, then a challenge to that theory or else new or conflicting information, and then finally a new or revised theory that attempts to account for the new info. Watch for that pattern, and answers like D will be much easier to select.