Logical Reasoning

PT101 · S2 · Q22 Copernicus’s astronomical system

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Copernicus’s astronomical system is superior to Ptolemy’s and was so at the time it was proposed, even though at that time all observational evidence was equally consistent with both theories.

Conclusion

Copernicus's system is superior to Ptolemy's, even when it was proposed.

Evidence

Ptolemy believed that the stars revolved around the earth at great speeds.

Copernicus correctly thought that a simpler theory is that the earth rotates on its axis.

Evaluate

This paragraph doesn't read too much as an argument, but the first sentence is an opinion ("superior"). Our usual goal when we're matching a Principle to an argument is to make the conclusion be the outcome of the principle, and a consideration from the evidence to be the trigger of the principle.

If the conclusion is saying "one system is superior to another", then we want a principle that helps us judge the superiority of a theory.

Why does our author think C's theory was better than P's theory?

P posited something that C found unlikely. And C thought of a simpler theory.

We obviously know that C's theory is borne out as the correct one, but why did the author find it superior at the time it was proposed, even though the available evidence was equally consistent with both theories?

The superiority must have been its simplicity. That's the famous principle known as Ockham's Razor (the literal phrasing is something like "avoid superfluous entities", but the usage is that ).

Goal

Look for something like, .

22.

The argument most closely conforms to which one of the following principles?

  1. Simplicity should be the sole

    Too Strong: sole

    The author thinks simplicity is the deciding factor here, but only because all observational evidence was equally consistent. The compatibility between theory and observational evidence is also something the author thinks is a deciding factor. This answer accuses the author of living by the maxim, "Any time I'm choosing among competing scientific theories, I will always pick the simplest one." This is a good illustration of the difference between Strengthen + Principle (Which of the following principles, if valid, most justifies the argument) and Necessary Assumption + Principle (Which of the following principles most conforms to the argument). IF this principle were valid, it would definitely justify the conclusion, but this question stem isn't asking us that.

    3% picked this

  2. If one theory is likely

    Bad Evidence Match

    We could stop reading at the first comma, because we can't match up the concept "one theory is likely to be true" with the evidence. Although we heard that Copernicus thought something Ptolemy believed was unlikely, that's not the same as the evidence telling us that either of the two theories was likely to be true or likely to be false.

    13% picked this

  3. If all observational evidence is

    Weak Evidence/Conclusion Match

    The evidence emphasizes that Copernicus's theory was "simpler", not "more intuitively true". Can we equate those? Ugh. It feels like a stretch. The conclusion is that one theory is "superior" to another, but this principle rules on whether one theory is "more practical" than another. Can we equate those? Also, seems like a stretch.

    20% picked this

  4. Correct

    Other things being equal, the

    Why this is right

    Hey, it's Ockham's Razor! This has the 1/2 Evidence, 1/2 Conclusion language match we seek in Principle answers. "other things being equal" at the time all observational evidence was equally consistent with both theories "the more complex" Copernicus had a simpler theory, Ptolemy had a less simple (more complex) theory "the inferior theory" Thus, Copernicus's theory was superior, Ptolemy's was inferior. If we were liking this answer but scared to pick it because we were thinking, "This principle allows me to argue that P's theory was inferior, but the actual argument was arguing that C's theory is superior", then we would just need to realize that those are completely interchangeable ideas. C's is superior to P's = P's is inferior to C's LSAT loves interchangeable rephrasings: All A's are B = No A's are not B, Not all A's are B = Some A's are not B If X, then Y = If not Y, then not X etc.

    Skill tested: Principle-Conform · how this choice captures the argument's function is the move to repeat next time.

    55% picked this

  5. Other things being equal, the

    Weaker Conclusion Match

    This is just as enticing as (D), because it fits the author's evidence, which was about which theory was simpler / more complex. But this doesn't fit the author's conclusion as well as (D) did. The conclusion was about which theory was superior / inferior. This answer is acting like the conclusion was talking about which theory was more scientifically important / less scientifically important. While the concept of importance seems connected to superiority / inferiority, it doesn't hit the nail on the head the way that (D) does.

    8% picked this

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