Reading Comprehension

PT144 · S1 · P4 · Q24 Karl Popper

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Passage A

Passage A

The author presents and mildly critiques the ideas of Karl Popper regarding positive and negative evidence.

She starts out acknowledging the merits of his contribution. Negative evidence is definitely more powerful than positive evidence, since negative evidence has the power to prove a theory wrong, whereas positive evidence only shows that "so far, it's always been correct".

The rest of the first paragraph involves a series of attributions to Popper. Frequently, if an author is taking pains to separate someone else's ideas from her own, it's because a disagreement is around the bend. We can also see a negative attitudinal marker with the work "hyperbolic", which means exaggerating to an unrealistic degree.

Paragraph 2 delivers on our suspicions with a "However" author pivot. The second paragraph stresses that Popper goes overboard in acting like , since in the real world it's messier than that.

Testing scientific theories (to see whether we get positive or negative evidence, i.e. matching the predictions vs. not-matching the predictions) means assuming that other theories are correct, that your measuring instruments are working correctly, and potentially other assumptions.

So when negative evidence is found, it isn't immediately clear what that's telling us: it could be telling us, as Popper is thinking, that the theory we're testing is wrong but it could just be that one of our other theories is wrong, or that something went awry with the measurement.

Passage B

As we start the second passage, we're listening attentively for the first signs of Overlap. In the second sentence, we see "auxiliary assumptions" (which to me sticks out, because prior to Passage A, I had never heard the expression "auxiliary premises" before).

So we pause and possibly re-read that part of Passage A to dial in the meaning / significance of auxiliary assumptions to Passage A:

when a measurement doesn't match Theory A's predictions, - maybe Theory A is wrong - maybe an auxiliary assumption is wrong (e.g. Theory B is wrong. Idea X is wrong. Our instruments failed)

Passage B then takes us through two different examples.

Uranus Mercury

Measure U's orbit M's orbit doesn't didn't match didn't match match Newton's theory Newton's theory theory Reason for negative evidence

Aux. assump = wrong. Theory = wrong. We'd assumed there At first we thought weren't any planets aux assump of no nearby Uranus, planets near M was because we wrong, but once hadn't found Einstein's math Neptune yet worked, we found out Newt's theory was wrong.

24.

The author of passage A would be most likely to take which one of the following results mentioned in passage B as support for the claim made in the last sentence of passage A?

  1. the discovery of Uranus

    Bad Match

    Once Uranus was discovered, then Newton's theory could make a prediction about it. 1. Uranus discovered 2. Newton's theory predicts X 3. Uranus is not at X (negative evidence) 4. Aux assumption that there were no nearby planets was changed. 5. Neptune discovered. Newton's theory temporarily vindicated. If we're trying to support Passage A's sentence that "negative evidence is rarely conclusive", we want #3 through 5 there. The discovery of Uranus is way too far upstream.

    2% picked this

  2. Correct

    the initial failure of Newton's

    Why this is right

    The initial failure of Newton's theory to predict Uranus's orbit was negative evidence, as was the initial failure to predict Mercury's orbit. The author of A's last sentence is that "negative evidence is frequently inconclusive", meaning "you can have negative evidence, but you can't conclude that the theory is therefore wrong (might be an aux assump that's wrong)". In the case of Uranus, we found out the theory was fine, the aux assumption of "no nearby planets" was wrong (Neptune was hangin' out nearby). In the case of Mercury, we found out Newton's theory was actually wrong. Einstein made a better one that correctly matched Mercury's orbit. So from the negative evidence of Mercury, the result was "Newton's theory is wrong". From the negative evidence of Uranus, the result was "we can't conclude Newton was wrong; we were wrong about an aux assumption." Thus, it's support for author A's claim that negative evidence is frequently inconclusive.

    Skill tested: Author Opinion · how this choice captures the passage's function is the move to repeat next time.

    48% picked this

  3. the ultimate failure of Newton's

    Opposite

    This is actually the part of Passage B where negative evidence (Mercury's actual orbit didn't match predictions) resulted in people concluding that Newton's theory was wrong. We're looking for a result where the negative evidence didn't prove that the theory was wrong.

    14% picked this

  4. the failure to find Vulcan

    Opposite

    The Mercury story is one in which negative evidence resulted in people concluding that Newton's theory was wrong. We're looking for a result where the negative evidence didn't prove that the theory was wrong.

    29% picked this

  5. the success of Einstein's general

    Opposite

    Einstein's success at predicting was positive evidence for the superiority of his theory, and Newton's failure to predict Mercury's orbit was negative evidence. The Mercury example was a case when negative evidence was indeed indicative of the fact that the underlying theory was wrong (not the aux assumptions).

    6% picked this

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