Doubts about some patterns of choices in Critical reasoning

[resolehtmai]

Often a CR question asks "Which of the following most weakens the prediction that the plan will succeed in city X?"
Are the following choices valid weakeners?
A) The plan was implemented in city Y and it did not succeed.
B) The plan was last year implemented in city X, but did not succeed.
C) Some experts say the plan will not succeed.
D) Many factors will not let the plan succeed.

[RonPurewal]

Often a CR question asks "Which of the following most weakens the prediction that the plan will succeed in city X?"
Are the following choices valid weakeners?
A) The plan was implemented in city Y and it did not succeed.
B) The plan was last year implemented in city X, but did not succeed.
C) Some experts say the plan will not succeed.
D) Many factors will not let the plan succeed.

(a) Depends on context. If the two cities are alike in ways that are relevant to the plan, then, sure. If not (or if we just don't know), then, no.

(b) Depends on context. If the situation is similar enough to last year's, then, sure. If not (or if we don't know), then, no.

(c) Probably no influence. However, if the experts' words actually have some bearing on the situation (e.g., their predictions cause some stock value to fall, and then some company can't fund something anymore), then, sure.

(d) The way you've written this ("factors will not let..."), it actually guarantees that the plan won't work. ("Will not" does not admit uncertainty; it's used for something that definitely won't happen.)
That's not how CR weakening problems work. The correct answers aren't things that conclusively disprove the argument; that would be too easy/obvious. Instead, the correct answers will be things that weigh against, but don't completely disprove, the argument.

[RonPurewal]

By the way -- If you're trying to make "rules" that work independently of context, then ... well, don't. It's impossible.

That's why CR is on the exam: you can't make rules for it. (If you could do that, you would be holding the secret to artificial intelligence!)

[resolehtmai]

Thanks Sir. great and clear answers.

[RonPurewal]

you're welcome.