Reading Comprehension

PT144 · S1 · P4 · Q27 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.

27.

Which one of the following scientific episodes is most analogous to the discovery of Neptune, as that episode is described in passage B?

  1. Galileo proposed that ocean tides

    Weak Match

    We have a prediction that turned out wrong, but that's it. We predicted X, based on Y. The prediction didn't seem right. Maybe Y is wrong, or maybe we were wrong about Z? We then discover Z. There's no part of this answer that involves "Once we found out Galileo's prediction was wrong, we discovered this other thing."

    5% picked this

  2. By observing "variable stars"—stars that

    Bad Match

    We want something like - We thought X was Y, but our measurements said we were wrong. That led us to discover Z, which is why our measurements were wrong. This sounds more like - We thought X was Y, but really it's Z. That allowed us to settle a debate.

    7% picked this

  3. Walter Alvarez postulated that an

    Bad Match

    This answer involves a prediction that is supported by multiples lines of evidence (high iridium in rock samples as well as a large impact crater). There's no conflict between prediction and data. The Neptune discovery involved a prediction (about Uranus) that was at odds with observed data, which led to us discovering Neptune.

    12% picked this

  4. Bernard Brunhes discovered rocks that

    Bad Match

    We want something like - We thought X was Y, but our measurements said we were wrong. That led us to discover Z, which is why our measurements were wrong. This sounds more like - We discovered an X that was unlike present day X. So we concluded that X has changed over time.

    4% picked this

  5. Correct

    When a neutron decays into

    Why this is right

    We wanted something like this: We predicted X, based on Y. The prediction didn't seem right. Maybe Y is wrong, or maybe we were wrong about Z? We then discover Z. We thought (because of the law of conservation of energy) that any physical or chemical process neither adds nor subtracts energy from the universe. But then we measured what happens when a neutron decays, and the combined energies of the byproducts is less than the original. Does that mean that the law of conservation of energy is wrong? Maybe, but maybe our assumption that neutrons break down only into a proton and an electron is wrong. Asking this question led Pauli to say, "there must be some other particle that we're failing to account for" and this led to the discovery of this 3rd particle.

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

    72% picked this

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