Necessary Assumption - LSAT Logical Reasoning

The psychologist gives a description of a certain repeated pattern of behavior which involves an addict and another person to whom the addict is close. That pattern reflects how one person’s behavior triggers responding behavior by the other, such that the behavior of both people is constantly being reinforced. The credited response must capture this mutual-reinforcement phenomenon. The argument by the psychologist is not calculated to tag all addicts as manipulative and untrustworthy; nor does it warn against having an intimate relationship with all addicts. Finally, the argument does not concern itself with how an addict develops his or her behavior pattern. So all of the other answer choices, to one degree or another, miss the mark.

To answer this question, it is necessary to recognize that while appointment criteria are set forth for the board of directors, they are applied to the position of Treasurer. We are never told that a Treasurer is a member of the board of directors. Thus, the conclusion is only warranted if eligibility for appointment to the board is a necessary condition for appointment to the position of Treasurer.

Since 25 percent of wood pulp in the Class B sheets comes from recycled Class A sheets, the maximum number of Class B sheets is 4 times the number of Class A sheets. However, the correct answer correctly notices that the maximum number of Class B sheets can be produced only if all pulp from the Class A sheets can be recovered through recycling; if less than all of the pulp can be recovered, the actual number of Class B sheets produced will fall short of the maximum. For example, if there were 100 Class A sheets recycled, but only 25 percent of pulp could be recovered through recycling, only 100 Class B sheets could be produced.

The argument asserts that different training programs cause soccer players to be faster than baseball players. The next assertion is that baseball players would become more athletic if they used training programs of soccer players. This only follows if becoming faster necessarily makes one more athletic.

If injured people might not be compensated even if every driver has insurance, then the argument's conclusion does not follow.

The argument's assertion is that production of pencil sharpeners cannot be profitable. The argument does not link this assertion to the rest of the argument, however. Instead, it supports the claim that demand has decreased. The argument assumes that decreased demand has made production of pencil sharpeners unprofitable.

The passage asserts that the campaign for increased care of the environment is doomed to fail. The passage demonstrates, however, only that ice caps will melt despite the campaign. The argument's conclusion is only properly drawn if melting ice caps necessarily means that the campaign has failed.

The correct answer is:

Internet cafes do not offer any other services, aside from online access, that would enable them to be profitable.

The crux of the argument is that internet cafes are not successful because the service that they offer -- online access -- is now made available for free by other outlets. However, this argument depends on the assumption that internet cafes do NOT offer any other services that would make them profitable -- such as a community base that would attract clients, or food and beverages that consumers would be interested in buying.

To answer this question, it is necessary to realize that the criteria to practice law requires that a person not demonstrate moral turpitude. Therefore, there has to be a link between Smith's embezzlement and the moral turpitude. Therefore, if embezzlement demonstrates moral turpitude, then the argument flows logically.

To derive the assumption, we must first identify the conclusion of the argument—to wit, “Non-analytical thought offers a more profound way to engage with reality than does analytical thought.” What is the evidence or premise to that conclusion? We can express it as something like this, as a paraphrase of what is expressed fully in the argument: “Analytical thought ignores ‘unity’ of all things.” What is a term or concept in the premise that does not appear in the conclusion? Answer: the notion of “unity.” So the assumption must contain within it some expression of that notion. More particularly, the assumption involves some notion of “grasping unity” as a way to penetrate “reality” in a more profound way. The credited answer choice expresses that notion precisely. The others miss the mark inasmuch as they do not express the key idea of “grasping unity” as a way to understand “reality” in a “profound” way.

In any assumption question, we must identify what term, concept, or idea is expressed in the evidence that does not appear in the conclusion. In this instance, the evidence concerns football running backs. Therefore, any viable answer choice must refer meaningfully to football. Any answer choice that does not do this should be eliminated. The essence of the argument here involves an assumption that football and basketball are comparable sports. So the correct answer is: Height and left-right preferences have a comparable value in football and basketball.

The assumption must speak to the issue of “experiencing suffering,” since that is the missing term in the conclusion. The correct answer links that new term to the conclusion regarding what humans ought to eat and not eat. Thus, the correct answer is: Only sentient beings that can experience suffering ought to be considered outside the realm of edible food for humans.

The conclusion speaks of free-writing as better than outlining when it comes to generating quality fiction. The premise (i.e., the evidence) for that conclusion speaks of "creative narration of events." That idea does not appear in the conclusion, so in order to link the premise to the conclusion, the assumption must address it in some meaningful way. The correct answer here does just that, by linking the idea of "creative narration of events" and the point in the conclusion about quality fiction.

The conclusion of this argument speaks to the ability to predict a race car's quickness in reaching maximum speed---horsepower alone won't permit an accurate prediction. Why? The argument states that the efficiency of the fuel-injection system varies among comparable cars. This suggests that the fuel-injection system is a critical factor in a car's ability to reach maximum speed. And that indeed is the unstated assumption. The "efficiency of the fuel-injection system" is the key term in the evidence portion of the argument that is not stated in the conclusion, and it is that key term that must be contained in the assumption. Any answer choice that does not mention that key term can be immediately eliminated.

The correct answer is an unstated premise necessary to the argument’s conclusion, which is that “overall employee performance among new hires should increase.” Without this premise, it is possible that new hires’ performance will merely remain the same, as the company’s new hires may have all had significant work experience (despite it being a preference and not a requirement).

The article assumes, without stating, that multivitamins’ only benefits are equivalent to those gained by eating a proper amount of fruits, vegetables, and whole grains. If this assumption is false, the argument is invalid, as there could be other reasons to take multivitamins.

This is a formal logic question that calls for an inference based upon the logical structure of the argument. It is best to reformulate the statements into simple conditional declarations (if-then statements) and then note the contrapositive. Here is a suggested reformulation: If masterpiece (M), then tight melodic structure (TMS). Contrapositive: If no TMS, then not M. If not appealing to aficionados (not A), then not M. Contrapositive: If M, then A. Some recent classical music (R) are masterpieces. Therefore, some R have TMS and are M. All of the answer choices that express one of these conditional statements follow logically from the argument presented. Those are the incorrect responses. The correct response—in effect, If TMS, then A (“Only classical music that has a tight melodic structure appeals to classical music aficionados”)—does not comport with any of these logical conditional statements.

First we must identify the conclusion: It is wrong to conclude that the Tibutu do not understand the concept of private property. Second we must articulate the premise or evidence for that conclusion: drinking and using water can lead to knowledge of water, even without attaching a name to it (experiencing something is enough to gain knowledge of that thing). The assumption must link the premise or evidence to the conclusion. To do that, we must identify the word, phrase, or concept (or idea) in the premise or evidence that does not appear in the conclusion. That is relatively easy here—the idea of experiencing water as a way to gain knowledge of it is the key point that must appear in the assumption. The correct response expresses the key idea in the premise and links it to the conclusion. Note that the answer choice that invokes the idea of experiencing something as a way to know it states something extreme—namely, that is “better” to experience something than to have a name for it when it comes to gaining knowledge of it. While perhaps true, that qualitative judgment is not expressed or implied in the argument, so it is not the correct answer choice.

This is a formal logic problem. First, note the conclusion: If Omega, then not Homunculus. Second, note the evidence/premises: If Xenon, then not Alpha (or you can put it in its contrapositive form: If Alpha, then not Xenon).; and If Omega, then Xenon. To find the assumption, look for the missing term in the evidence/premises that does not appear in the conclusion---namely, Alpha. So we can eliminate any answer choice that does not mention Alpha.

To elaborate in order to select the proper answer choice, we can see that the premises come down to this (combining the two propositions): If Omega, then not Alpha. The conclusion states: If Omega, then not Homunculus. Therefore, the assumption has to be If not Alpha, then not Homunculus. Take the contrapositive of that: If H, then A. And that is what credited answer choice states.

First, identify the conclusion: "Rapid but foolhardy change may occur in a society that quickly improves its public education system at the high school level but does not address the problem of money in politics."

Second, identify the key terms in the evidence/premises with a paraphrase of what is presented in the passage: for example, you might say, "campaign contributions (money in politics) distorts the electoral process."

What key term in the evidence/premises does not appear in the conclusion? Obviously, something relating to unbridled campaign contributions (i.e., the distorting affects of money in politics). That key term or idea must be at work in the assumption, and therefore it must appear in the correct answer choice. So we can quickly eliminate any answer choice that does not speak to this key term or idea.

The credited response speaks directly to the distorting effects of uncontrolled money in politics without the use of extreme language and without resort to unnecessary "ought" or "should" assertions. Note how the wrong answers either use extreme language or resort to claims that urge some kind of action (whereas the argument does not assume something about action that is needed---though it may lead to an INFERENCE that certain action would be wise, but that is not an assumption).