The author says “remaining silent leaves the dangerous client out of prison.” This implies that the dangerous client is now out of prison. As an analogy, if I say “she stayed home because of the storm,” I’m implying that she was home at the onset of the storm. So A and B, which can both be construed to mean that some violent criminals receive therapy behind bars, are both irrelevant.

AC C says that most of the children in the control group were already familiar with the ads. This basically means they had already watched the ads. Whether or not they were influenced is another matter.

For simplicity, we assume that there are only two possible attitudes one can have toward breakfast cereals: liking them (L) or disliking them (D). We require that one has exactly one attitude toward breakfast cereals at any time. We require in addition that the attitude change as a result of a series of events is composed of a single initial attitude, a single final attitude, and any number of intermediate attitudes. We write LDDL, for example, to mean a change of attitude from liking breakfast cereals to disliking them to disliking them to liking them as a result of a series of events, and we say that the first L in this case marks the initial attitude with respect to the series of events, the second L marks the final attitude, and the double D the intermediate attitudes. We require that the attitude change as a result of a single event has no intermediate attitudes. It follows that there are four possibilities in total regarding attitude change as a result of a single event: LD, DL, LL, DD. And since each individual has exactly one attitude at any given time, each individual experiences exactly one of the four types of attitude change as a result of any given event. We say that an individual is influenced by an event if the individual experiences LD or DL as a result of the event. Clearly, an individual cannot be both influenced and not influenced by an event, but an individual has to be either influenced or not influenced by an event.

For a group of people the situation is more complicated, as members of the group may experience different kinds of attitude change as a result of the same event. We say that a group has been influenced by a certain event when most of the group members have been influenced by the event, and that a group has not been influenced by an event if half or more than half of the group members have not been influenced by the event. It immediately follows that a group cannot be both influenced and not influenced by a certain event, and that a group has to be either influenced or not influenced by a certain event. Whether a group has been influenced by an event we call the group’s influence outcome with respect to the event. We write Y if it has been influenced by the event and N otherwise.

We assume that an individual does not experience attitude change outside of an event. This means that the initial attitude of an individual with respect to an event is the same as the individual’s final attitude with respect to the immediately preceding event, namely the event such that there is no other event between it and the event in question. This raises the question of whether this dependence will constrain influence outcomes in some way. Fortunately, it is easy to show that it is possible for a group to have either influence outcome with respect to an event regardless of what the influence outcome was in the immediately preceding event. Suppose most members of a group experienced LD as a result of the immediately preceding event. If these members all experience DL as a result of the present event, the group is influenced by the present event. If, on the other hand, these members all experience DD as a result of the present event, the group is not influenced by the present event. This shows that a group influenced by the immediately preceding event can be either influenced or not influenced by the present event. By the same argument it can be shown that a group not influenced in the immediately preceding event can be either influenced or not influenced by the present event. Note that this proof says nothing about whether, in all cases, a group’s influence outcomes with respect to an event are not constrained by its influence outcomes with respect to the immediately preceding event. It only shows that this is so in some cases. But this weaker claim is enough for our purposes.

Now, we have two events, two watchings in particular, one from the stimulus and one from AC C. We call the former the later watching, the latter the earlier watching. Further, we have two groups of children. One of them we know to have participated in both watchings. We call this group the experimental group. The other group we call the control group. Note that we do not know if the control group has participated in the earlier watching. We assume that the earlier watching immediately precedes the later watching for the experimental group and, if the control group has participated in the earlier watching, for the control group as well. We denote the experimental group’s influence outcome with respect to the earlier watching A, the experimental group’s influence outcome with respect to the later watching B, the control group’s influence outcome with respect to the earlier watching C, and the control group’s influence outcome with respect to the later watching D. If, say, the experimental group was influenced by the earlier watching, we say A takes as its value Y. If the control group has not participated in the earlier watching, we say C takes as its value N. This shorthand is justified for our purposes.

We determine whether the study’s conclusion is warranted in the following way. If at least one of A, B, C, D has as its value Y, the conclusion is not supported. Otherwise, it is. It is easy to see that, of all sixteen possibilities, only one has no Y in it, in which case the conclusion stands.

Nowhere in the stimulus is it mentioned that the beliefs that the subjects acquired as a result of reading those statements match the statements. Perhaps the statements are about something one would usually not think enough about to have a belief about but would nevertheless immediately strike one as false once one is presented with them. Take for example the claim “Rabbits were recently discovered on Neptune.” Maybe the subjects only ever hear about potential sources of life on Mars that they have never really thought about the possibility of life on any other planet, but by considering the multifarious conditions that would have to have obtained for such a discovery to be made and evaluating against their understanding of biological processes and the current state of technology just how likely these conditions could have actually obtained, the subjects came to the conclusion that such a discovery would be highly unlikely. In other words, the exposure to the false claim actually resulted in the acquisition of a correct belief. It is thus unsurprising if the subjects have been able to form from the false claims presented to them only correct beliefs that they would continue to hold on to these beliefs even when told the claims are false: they already knew them to be so!

This question is genius. It presents a bit of seemingly irrelevant context before diving into an argument and an extended counterargument, by the end of which the little bit of context is more likely than not forgotten. But turns out this bit of context is crucial for getting the question right.

The flaw is straightforward. The author concludes from the fact that an inadequate argument has been advanced in favor of a claim that that claim is false. To weaken the argument, we only need to supply an adequate argument in favor of the claim. The correct AC does the job—but only if one has not totally forgotten about the first sentence of the stimulus.

Chose D. I usually go from E to A to avoid falling for the psychological tricks the LSAC so so loves. But who wouldve thought theyd put a trap AC on both sides of the correct AC… Well done LSAC well done

When the cost of pollution is not reflected in gas prices, it usually does not affect consumers’ decisions about how much to drive. But when this cost is reflected in gas prices through heavier taxes, consumers tend to pollute less. These two observations together strongly support the hypothesis that when the cost of pollution is reflected in gas prices, it tends to affect consumers’ decision about how much to drive. In particular, they are likely to drive less, with the result that they are likely to buy less gas and pollute less. AC C differs from this only by “fully.” But “fully” actually makes AC C weaker and the threshold of proof lower: it allows for the possibility that consumers tend to be indifferent when the cost is only somewhat reflected in gas prices.

I think I finally got it!!

P1: Green-manure crops improve soil structure.

P2: The abandonment of green-manure crops led to poor soil structure.

C1: One way of significantly improving soil structure is to reintroduce green-manure crops. (from P1 and P2)

A1: Any method of significantly improving soil structure requires the abandonment of chemical fertilizers.

C2: In order to significantly improve soil structure, chemical fertilizers must be abandoned. (from A1)

C1 and A1 together imply that the reintroduction of green-manure crops for the purpose of significantly improving soil structure requires the abandonment of chemical fertilizers. This matches AC E.

Alternatively, the negation of AC E says that all farmers would grow green-manure crops without abandoning the use of chemical fertilizers. If this is the case, since growing green-manure crops is one way of significantly improving soil structure, the abandonment of chemical fertilizers is not necessary for significantly improving soil structure.

This is an inductive argument. It concludes from the observation that something shares some properties with something else that it shares with that something else all the defining properties that make that something else what it is. To weaken the argument, we only need to show either that the object has a property that is not exhibited by most speaking staffs or that most speaking staffs have a property that is not exhibited by the object. The correct AC does the latter.

I’m so offended by this question. So people of Indian ethnicity eat more Indian curries? Just like Americans eat more burgers, African Americans eat more fried chicken, Chinese people eat more rice, and Japanese people eat more sushi? Jeez. Listen to yourself, LSAC. Yall should be ashamed of yourselves. If anybody’s organizing a petition to get this question removed retroactively, I’ll be here to sign it.

The author concludes from certain advantages of painted paper and disadvantages of paint that painted paper should be used for a certain goal. Two kinds of assumptions are involved: analogical and conditional. From the analogical point of view, the author has to assume that the advantages mentioned of painted paper are not shared by paint, and conversely the disadvantages mentioned of paint are not shared by painted paper.

AC A almost says this but ends up being a little too strong. We only need the varying textures to interfere with the pure effect of the color itself to a lesser degree in the case of painted paper than in the case of paint. Perhaps the varying textures produce a smaller range of variations in the effect of the same color in a given context in the case of painted paper than in the case of paint, but we do not need this range to collapse to a singleton in the case painted paper, as AC A suggests we do.

From the conditional point of view, there is a gap between the cited advantages of painted paper and the goal we are interested in achieving. If these advantages are not at all useful for the achieving of the goal, the argument would be severely weakened. In other words, the author has to assume that these advantages are at least somewhat conducive to the fulfillment of the goal. And this is exactly what AC D says.

I find that one reason some difficult questions are difficult is because multiple kinds of reasoning are involved but the correct AC tends to address the least obvious one.

There are two gaps in the argument. Our author assumes that, first, a book that gives pleasure is intended by its author to give pleasure and that, second, at least some of what is written is not true in a book whose author cannot impart to the readers the truth of their subject matter. Also, our author argues by contradiction, so she assumes the opposite of the final term of the conditional chain. Our author assumes, in other words, that it is not the case at least some of what is written in any popular book is not true. There are also the standard assumptions on the LSAT that (✱) if it is the case that P, it is reasonable to say that P, that (✱✱) if it is the case that /P, it is not reasonable to say that P, and that (✱✱✱) if it is reasonable to say that P and it is reasonable to say that Q, it is reasonable to say that P & Q. We also recall from basic logic that (✱✱✱✱) if A → (B → C) and C → D, then A → (B → D) and that (✱✱✱✱✱) if (A → B) → A, then (A → B) → B.

The argument structure is clear enough other than the part where a proposition is repeated in different words. The author is basically spelling out the details for us: by “one could determine the truthfulness of a book simply by looking at its sales figures,” she means “[i]f the book were very popular, one could reasonably conclude that it gave people pleasure.”

The argument is thus reconstructed as follows:

P1. If it is the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter, then it is the case that it is reasonable to say that a popular book gives pleasure.

A1. A book that gives pleasure is intended by its author to give pleasure.

C1. If it is the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter, then it is the case that it is reasonable to say that a popular book is intended by its author to give pleasure. (By P1, A1, ✱, ✱✱✱, ✱✱✱✱)

C2. If it is the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter, then it is the case that it is reasonable to say that the author of a popular book cannot impart to their readers the truth of their subject matter. (By C1, ✱✱✱✱✱)

A2. If the author of a book cannot impart to their readers the truth of their subject matter, at least some of what is written in the book is not true.

C3. If it is the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter, then it is the case that it is reasonable to say that the at least some of what is written in a popular book is not true. (By C2, A2, ✱, ✱✱✱)

A3. It is not the case that at least some of what is written in any popular book is not true.

C4. It is not reasonable to say that at least some of what is written in any popular book is not true. (By A3 and ✱✱)

C5. It is not the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter. (By C4 and A3)

Proof of C1.

From A1 and ✱ we know that (p1) it is reasonable to say that a book that gives pleasure is intended by its author to give pleasure. From P1, p1, and ✱✱✱✱ we know that (p2) if it is the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter, then it is the case that it is reasonable to say that a popular book gives pleasure and it is reasonable to say that a book that gives pleasure is intended by its author to give pleasure. From p2 and ✱✱✱ we know that if it is the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter, then it is the case that it is reasonable to say that a popular book gives pleasure and a book that gives pleasure is intended by its author to give pleasure. It immediately follows that if it is the case that the author of a book that intends to give pleasure by writing the book cannot impart to their readers the truth of their subject matter, then it is the case that it is reasonable to say that a popular book is intended by its author to give pleasure. □

The key to this question is that we must be careful to distinguish between two levels of propositions, propositions about the surveyed physicians and propositions that are their beliefs. The correct AC is obtained by applying “most + most > some” twice, once at each level.

Let M denote the proposition that most of the surveyed physicians are influenced by gifts, and N the proposition that most of the surveyed physicians are not influenced by gifts. Clearly M and N form a mutually inconsistent list of propositions, since together they would imply that some of the surveyed physicians are both influenced and not influenced by gifts. This is the first application of “most + most > some.”

P1: Most of the surveyed physicians believe that they themselves are not influenced by gifts.

P2: Most of the surveyed physicians believe that N.

C1: Some of the surveyed physicians believe that they themselves are not influenced by gifts and that N. (From P1, P2; this is the second application of “most + most > some”)

A1: A consequence of these two beliefs is that M & N. (And we know from above that this is a mutually inconsistent list)

A2: For any list of propositions Γ, if a consequence of Γ is a mutually inconsistent list of propositions, one believing that Γ is mistaken in believing at least one of the propositions of Γ.

C2: Some of the surveyed physicians are mistaken about either their belief that they themselves are not influenced by gifts or their belief that most of the surveyed physicians are influenced by gifts. (From C1, A1, A2)

What if most cats are not evil? Maybe all the evil animals are cats.

Doesn’t “often” just mean “sometimes”? I eliminated this AC because I thought Jolene would also agree. After all, they concede that “some shrimp farms have proved unsustainable and have been quickly abandoned.” #help

Q27

We have three possibilities: noncohesive groups, cohesive groups with groupthink, cohesive groups without groupthink. The first two avoid objections (noncohesive groups directly, cohesive groups with groupthink indirectly), whereas the third takes part in constructive backandforths where participants are fully comfortable expressing their opinions and therefore exploration of a wide range of issues is permitted. AC B is thus supported.

LSAC = ethnocentric hypocrites

Another reason why E is wrong is because it’s too weak. Enthusiasm for new educational aids is only “often” not proportional to the pedagogical effectiveness of those devices. Even if “often” is changed to “most,” it’s not clear if the case of the calculators conforms to or falls outside the generalization. It can thus either strengthen, weaken, or have no effect. If “often” is changed to “always,” however, I think it should be ok as a direct conclusion strengthener.

This makes so much sense!! I got to the correct AC by elimination, but I just couldn’t see for the longest time how it’s an NA because I was adopting the first interpretation. Hate it when the LSAC allows this to happen.

AC C is wrong because for it to weaken, we need the additional assumption that it has been persuasively established that those “most animals that carry rabies” do need to be removed from buildings, in which case the comparison would provide support for the conclusion that bats, like those animals, also need to be removed from buildings, which would badly weaken Pratt’s argument. But what if it has been persuasively established that none of those animals actually pose enough risk for their removal from buildings to be warranted? Then the comparison created by AC C would actually strengthen Pratt’s argument.

AC B is difficult because the first part (“less mobile”) either has no impact or even strengthens, but the second part (“more aggressive”) weakens by neutralizing the effect of Pratt’s premise: even though bats are typically shy and rarely bite, when they are rabid, they get super aggressive and bite every single person that happens to be in their way.

The argument has two classic flaws. In assuming that the salability of car parts accurately reflects the salability of cars, it commits the part/whole flaw. In assuming that what is true about demand and salability in the context of junkyard sales holds generally, it commits the sampling flaw. The correct AC addresses the part/whole flaw, even though it could just as easily have decided to address the sampling flaw.

The study shows that children who engage in impulsive behavior are more likely to have the gene variant. In other words, there is a correlation between the gene variant and impulsive behavior. The implicit conclusion from the study is that there is a causal relationship between the gene variant and impulsive behavior. And since the impulsive behavior of these children resemble thrill-seeking behavior in adults, the author concludes that the gene variant causes people to tend to behave in a thrill-seeking way.

The gap between impulsive behavior and thrill-seeking behavior is the most obvious flaw. The second most obvious flaw is the move from correlation to causation. That the correct AC does not address either makes the question difficult.

A is weak (“many”) and requires the assumption that impulsive adults tend to behave in a thrill-seeking manner.

B looks irrelevant at first, but by showing that the study does not support the correlation reading, it undermines the connection between the gene variant and impulsive behavior.

C might be construed as a strengthener but is probably better taken to be irrelevant. We care about the connection between the two kinds of behavior, not about what a group of people tend to believe about this connection, and we know that beliefs are not necessarily reliable.

D is open to interpretation and either weakens, strengthens, or is irrelevant. If children that do not behave in an impulsive or thrill-seeking manner invariably grow up to behave in a thrill-averting manner, the link between the impulsive behavior and thrill-seeking behavior is weakened. If the children that behave impulsively but not in a thrill-seeking manner invariably grow up to behave in a thrill-seeking manner, the link between the two kinds of behavior is strengthened. If the behavioral tendencies involved do not include either impulsiveness or thrill-seeking, our argument is untouched.

E is irrelevant. If the gene is also correlated to procrastinating behavior so that most people with the gene tend to exhibit both thrill-seeking behavior and procrastination, our argument is untouched.

I thought “explicit” referred to explicit functions as opposed to implicit functions. We’re basically given a function K that maps each stage K(n) of the construction to the next stage K(n+1) with K(K(n)) = K(n+1), and the Koch curve would be defined as the infinite intersection of K(n) with n ranging over the natural numbers plus zero (K(0) being the line with no bumps).

Also, fractals are so fun. Please don’t let this passage stop you from learning more about this fascinating topic. Math students have the same complaint that textbook writers for some reason typically prefer to spend paragraphs describing concepts in words that everybody can get immediately if you just show them a picture. The age old bias of logos supremacy I guess 😮‍💨

Q22

It’s important to be clear that the passage states none of the AC’s. Both A and B have textual support; C is not mentioned at all; and D and E contradict the passage. A is supported because the author says the contingency-fee agreements “shift the risk of not recovering those costs, and of not obtaining a damages award that will pay their lawyer’s fees, from the client to the lawyer” (52-55). For A to work, we need to assume that the risk described largely intersects “the risk of pursuing a legal action.” B is supported because the author says the contingency-fee agreements are “intended to prevent lawyers from gaining disproportionately from awards of damages” (17-19). For B to work, we need to assume that this intention would more likely than not be borne out by actual practice. I chose B because I thought A was a trap AC, but now in review it’s clear to me that the assumption needed to make A work is more reasonable than that needed to make B work, so A is the superior AC.

Q23 A vs D

I was confused for the longest time about just what the difference is between A and D. A is the first AC that comes up and echoes the phrase too literally, whereas D also makes sense but comes later and uses different language, so under timed conditions, I would guess that A is a trap AC and go with D without spending more time trying to tease out their differences. But in review it’s absolutely necessary to do so.

Logical asymmetry is essentially the idea that positive evidence alone cannot prove a hypothesis, whereas negative evidence alone can disprove a hypothesis. Note the scope of the conjuncts: they are talking about whether particular kinds of evidence can prove/disprove hypotheses.

But what does the author say Popper maintains? “[T]hat positive evidence has no value as evidence and that negative evidence is tantamount to disproof.” Note the subtle scope shift: we’re no longer concerned with proving/disproving hypotheses; we’re now evaluating different kinds of evidence based on the extent to which they may be consider valuable.

Our author is essentially accusing Popper of proposing an excessively restrictive notion of evidence by having the question whether or not a piece of evidence has value depend solely on whether or not it can on its own prove/disprove hypotheses. Our author suggests that, on Popper’s view, positive evidence is entirely useless because by itself it cannot prove hypotheses, and negative evidence is useful because it can disprove hypotheses—indeed, it is so only to the extent that it can disprove hypotheses.

But what if positive evidence can serve some other purposes unrelated to proving/disproving hypotheses? And likewise what if the use of negative evidence is not limited to disproving hypotheses? Popper, as portrayed by our author, essentially commits a flaw of reasoning: he falsely concludes from the fact that an entity lacks a property whose presence would be considered valuable and another entity possesses the property that the former is not valuable while the latter is; he takes for granted that a piece of evidence is valuable only to the extent that it is able on its own to prove or disprove hypotheses; he fails to consider the possibility that an entity devoid of a property whose presence would be considered valuable may nevertheless be valuable in some other way.

AC A is wrong because it’s descriptively inaccurate. As portrayed by our author, Popper is not overapplying the idea of logical asymmetry, which both our author and Popper believe holds in general. Rather, he’s distorting a reasonable claim into a highly implausible one. AC D fits this description better.

When I saw Augustine in the first passage and Kant in the second, I was so certain there was gonna be a method question and that the answer would be something like Both passages introduce a position ascribed to a figure from the history of philosophy before elaborating on that position. And then Q17 happened… 😮‍💨