#25 - Concept Reference, Parallel

[mN2mmvf]

Hi, can you explain why (A) is correct? I understood the black swan to be about the power of negative evidence -- the existence of just one disproves that all swans are white. I don't see how Mercury plays that role in the passage. I chose Neptune, because the existence of it alone proved the orbit of Neptune. (I don't love this answer, but it seemed the best of bad choices.)

[Francis O'Rourke]

As you said, the existence of the black swan disproved the idea "all swans are white." Since we are asked to find something analogous to this in the rejection of Newton's theories, we want the object, whose existence disproved an old idea. Because there was no nearby planet, Mercury's orbit alone disproved Newton's theory.

According to lines 52-56, to explain the existence of Mercury's orbit using Newtonian physics, Scientists hypothesized a planet called Vulcan. Since Vulcan does not exist, some scientists "began to think that perhaps Newton's laws were in error." Just as the existence of black swans made biologists question the hypothesis that all swans are white, the existence of Mercury's orbit made physicists question the theories of Newton.

Both Mercury and black swans serve as negative evidence; they undermined the existing theories.

The discovery of Neptune served as positive evidence for a Newtonian explanation of Uranus's orbit; it supported the existing theory.

[luna2021]

Hi, I now get that A is the correct answer - a negative evidence that is conclusive, or disproves a theory.
If the question was worded so that it did not specify for an AC of 'astronomical body' but just any 'thing', could these also be analogous answers?

- the nonexistence of Vulcan
- Einstein's general theory of relativity

Thanks!

[Rachael Wilkenfeld]

Hi Luna,

Neither of those would be a good answer here. The black swan is a piece of negative evidence---a specific example that proves that a theory would not work. Vulcan isn't negative evidence because it's not something that exists. Its existence can't prove a rule doesn't work because it doesn't exist. Mercury's orbit is something that exists, and so its behavior can prove a theory does not work. The theory of relativity is also not negative evidence because it's a theory. It's not evidence itself, but a guess at why something exists or not.

Hope that helps!