Passage - General Questions

[Administrator]

Please post your questions below! Thank you!

[JulesC]

Hello, could someone please break down and explain this passage. Especially the second paragraph in passage A as I'm not quite sure how it relates to the theory presented in the first paragraph.

[Jeremy Press]

Hi Jules,

Passage A's first paragraph presents Karl Popper's theory of negative evidence, which is that a single counterexample to a theory (a black swan is a counterexample to the theory that "all swans are white") disproves that theory. The rest of the first paragraph weaves in the author's initial critique of Popper (that Popper gives negative evidence too much power, when he treats positive evidence as having "no value" and negative evidence as "tantamount to disproof"), as well as a little more information on how Popper used his theory, i.e. that scientific research is about "searching for evidence that would disprove" theories.

The second paragraph of passage A is the author of Passage A's critique of Popper's theory, that it "does not capture the actual situation that scientists face." In other words, the author spends most of paragraph 2 illustrating how Popper's theory is too simplistic. If a theory entails a direct prediction (the theory that "all swans are white" entails the prediction that every swan we see will be white), then if we show that prediction is false (through the negative evidence of the black swan, for example) we disprove the theory. But the author says that scientific theories are rarely so direct in their predictions, and they require auxiliary premises in order to make predictions. So if a theory's prediction turns out to be false, it might be a problem with the theory or it might be a problem with the auxiliary premises. And we don't know which of those auxiliary premises is false in most situations, so negative evidence by itself shouldn't be taken as automatic disproof of a theory (negative evidence might be disproving one of the auxiliary premises).

Passage B presents two scientific scenarios involving a theory whose predictions turned out to be wrong. In the first paragraph, the theory about Neptune's orbit was wrong, not because Newton's theory of gravity was bad but because an auxiliary assumption (that there were no planets nearby) turned out to be wrong. So the "negative evidence" of Neptune's actual orbit didn't end up disproving Newton's theory.

In the second paragraph of passage B, the theory about Mercury's orbit was wrong, and no auxiliary premises or assumptions changed this conclusion (since there was no additional planet to affect Mercury's orbit), so Mercury's actual orbit turned out to disprove Newton's theory of gravity (and validate Einstein's theory).

Does that help to clarify the passages? Let us know!

Jeremy

[gwlsathelp]

In the second paragraph of passage B, the theory about Mercury's orbit was wrong, but no auxiliary premises or assumptions were wrong, so Mercury's actual orbit turned out to disprove Newton's theory of gravity (and validate Einstein's theory).

I thought that it was to be taken as negative evidence that since astronomers could not find Vulcan then one of the auxiliary premises was that Vulcan was affecting Mercury's orbit was false, and that Newton's Law on gravity was also incorrect. Perhaps I am not understanding the whole concept of positive and negative evidence. Can you all help further break down the concept and application?

[gwlsathelp]

Can you all help further break down the concept and application?

Can you all diagram it out in VIEWSTAMP and whatnot? Sorry if this is a lot, but preptest 76 forum is set up different than preptest 71 or 73, and it's thrown me off a little.

[Jeremy Press]

In the second paragraph of passage B, the theory about Mercury's orbit was wrong, but no auxiliary premises or assumptions were wrong, so Mercury's actual orbit turned out to disprove Newton's theory of gravity (and validate Einstein's theory).

I thought that it was to be taken as negative evidence that since astronomers could not find Vulcan then one of the auxiliary premises was that Vulcan was affecting Mercury's orbit was false, and that Newton's Law on gravity was also incorrect. Perhaps I am not understanding the whole concept of positive and negative evidence. Can you all help further break down the concept and application?

Hi gw,

Your understanding of the second paragraph of passage B is correct, and my phrasing there isn't as detailed or helpful as it should be. I'm editing it to say this: "and no auxiliary premises or assumptions changed this conclusion (since there was no additional planet to affect Mercury's orbit)."

Thanks, and hope this helps!

[gwlsathelp]

Hi Jeremy,

Thank you! This is indeed very helpful.