10. This LSAT assumption question contains an argument that works this way:
P1: All arguments against proposed plant presented by competing producers (i.e., Have a vested interest)
|A1: If have a vested interest g Do not present good argument|
Secondary Conclusion: No good arguments against proposed plant.
|A2: If no good arguments against g Proposed plant should be approved.|
|C: Proposed coal-burning plant should be approved.|
The tricky thing about this question is that a secondary conclusion and a primary conclusion appear. And, two assumptions appear -- one to connect the first premise to the secondary conclusion, and another to connect the secondary conclusion to the primary conclusion. Notice that the question stem asks for "an" assumption, not "the" assumption. As such, the correct choice could list either assumption. (E) contains the first assumption.
(A) is something that the author might believe, but we don't know this for sure, and it is not a required assumption. Negate the choice by placing "not" in between "would" and "stand" -- the argument is not weakened and thus (A) is not a necessary assumption.
(B) provides a conditional statement that confuses the sufficient and necessary conditions of the first assumption, and also replaces "Do not present good argument" with "Defective argument", which are not the same thing:
|Defective argument g Have a vested interest|
(C) provides a guess as to what the author might believe, not a required assumption. Who supplies the plant and whether or not they are pleased is irrelevant.
(D) provides a conditional statement that might be tempting:
|Good argument presented for g Proposal should be approved|
But "no good arguments against" does not necessarily equal "good arguments for". The contrapositive of the second assumption is this:
|Proposed plant should NOT be approved g Good arguments against|
11. Your patience is tested with this question because the choices are tough. Ensure that you know precisely what the error is before going to the choices.
The error works this way:
P1: X (traumatizing event) does not necessarily cause Y (phobia)
|P2: Y does not necessarily require X|
|C: X does not contribute to Y.|
In other words, X and Y are independent of each other, thus X does not contribute to Y. The error is that the belief that X and Y must be directly connected for there to be any contribution of X towards Y.
(A) describes reverse causality.
(B) refers to "some" events which may or may not include phobias. Also, the author never states or implies that there's "no" cause for phobias, just that traumatizing events do not necessarily cause phobias. Finally, the scientific investigation is irrelevant.
(C) describes circular reasoning.
(D) is the correct choice. (D) states that the Psychiatrist assumes that for X to contribute to Y requires that X and Y be invariably connected.
(E) describes confusing correlation for causation.
12. This LSAT main point argument contains a lot of information, but the heart of the argument is this:
P1: Decline in population often signals pollution, but equally as often signals natural change in ecosystem.
|C: If environmentalists attribute all population declines to pollution, then misguided.|
Choice (B) provides a paraphrase of the conclusion. Notice that the conclusion is in the conditional tense -- "if".
(A) states "overreact" but the passage states "misguided".
(C) refers to a conclusion that the author does not make. The author does not state that environmentalists are, in fact, misguided. Instead, the conclusion states "If environmentalists attribute all population declines to pollution, then misguided." We don't know from the passage whether environmentalists have actually attributed all population declines to pollution.
(D) contains "resisted" but there's nothing in the passage to imply or suggest that the environmentalists are "resisting" natural changes, or that the author is advising them not to "resist" changes. The passage is only about environmentalists' attribution of changes; the passage makes no mention or implication of environmentalists' actions taken on such attributions.
(E) confuses the information in the passage. If "as a result of pollution" were eliminated, and "is" were changed to "could be", then (E) might be a correct choice.