Must be true

mrm5844

I need help o Must be true questions. I have noo idea where to begin

stepharizona

Be sure to go through all of the lessons about MBT and MP, plus the notes offered below in each provide great insight.

What seems to be your main issue?

Cant Get Right

MBTs can actually get really tricky. They can cover essentially the entire spectrum of conditional logic, so you've got to really have that down. So start at the beginning with basic conditional logic.

notwilliamwallace

Hey mrm5844,

I am also going through the same topic right now and can provide some direction. These questions rely a lot on conditional logic so getting some practice with that would be a great place to start. There are a few things I have learned about this game, using which you can eliminate a few of the answer choices.

1. The right answer is inferred using the facts given in the stimulus. Lots of times, the test makers just provide a contrapositive of a conditional fact given, which you are to select as the right answer. Anything extra given in the answer choices that the stimulus doesn't even mention can be eliminated. Remember, the right answer doesn't have to be the author's main point. The answer choice can be provable by one lonely statement in the stimulus.

2. Be aware and suspicious of extremely strong language. Words like "never" and "all" are examples. When it come to must be true, choices with moderate language deserves more scrutiny. However, don't completely rule out answer choices with strong language. These answer choices maybe introducing a conditional logic statement that satisfies one of the statements listed in the stimulus.

3. Practice. Practice. Practice. This goes without saying. Honestly, the more you do such questions, the better you get at them. After going through some of them, the wrong answer choices will become very apparent to you.

Let me know if you need any help with these questions. With time, they will actually become enjoyable to do

stepharizona

Nice job @notwilliamwallace

notwilliamwallace

Thank you @stepharizona

OP, one thing I forgot to mention. Make sure you have a good knowledge of advanced conditional logic. Here is a little cheat sheet I created using the 7Sage curriculum:

1. Some = Atleast one. Could go to 100%.
Negation: None. Example: "Some people in Canada like hockey." Negation: "No one in Canada likes hockey".

2. All = 100% (everything).
Negation: Not all (0 - 99%). Example: "Everyone in Canada likes hockey." Negation: "Not everyone in Canada likes hockey"...OR..."Some people in Canada do not like hockey".

3. None = 0% (No one, nothing).
Negation: Some. Example: "No one in Canada likes hockey". Negation: "Some people in Canada like hockey"...OR..."At least one person in Canada likes hockey".

4. Most = 51% to 100% (Majority).
Negation: Not the majority (not most...less than half). Example: "Majority of people in Canada like hockey." Negation: "Less than half of Canadians like hockey".

5. Many = Some = Several = Frequently: Many is subjective in the LSAT but can be substituted for some in 99% of the cases. It also means atleast one. However, keep in mind that if the answer choice says "Many people like ice cream" and another one says "Some people like ice cream", in MBT questions, pick the one that's more moderate (in this case, "Some").
Negation: Not many. Example: "Many people in Canada like hockey". Negation: "Not many people in Canada like hockey". What "many" means is subjective, but know that it is atleast one.

6. Few = 0 - 50%. Basically, it's saying that "some people are...most are not".
Negation: None (to account for some) or Most (to account for most are not). Example: "Few Canadians like hockey." This means: "Some Canadians like hockey, but most do not". Negation: "Either no Canadians like hockey or most Canadians like hockey".

Besides knowing the six points above, it is imperative that you AND and OR statements. Those ones are fairly simple: AND in necessary splits and OR in sufficient splits. Why? Because in these situations, each condition one its own can prove the condition on the other side of the arrow. If AND in sufficient and OR in necessary, then the arrow doesn't split. For the contrapositive, AND becomes OR and OR becomes AND.

One question in MBT gave this situation: A --> B or C. Furthermore, B --> D and C --> E. At the end, they said, that D doesn't happen. From this, you know that B doesn't happen and that was the correct answer. They didn't even use any of the other parts of the stimulus to draft an answer choice. You see, nothing else besides the fact that B doesn't happen can be inferred from the info presented.

mrm5844

Do I used the same method for Must be False questions?

notwilliamwallace

@mrm5844 said:
Do I used the same method for Must be False questions?

Must be false (or, cannot be true) questions are very similar. The difference is that four of the answer choices could be true and one one of the answer choices is false given the facts stated by the author.

Example, "When I go to the amusement park, I only see two kinds of people, those who enjoy roller coasters and those who enjoy funnel cakes." (in this case, the and acts as an or as he is dividing the people at amusement parks into two kinds of people. One of the groups of people has to be present at the park.)

A. Most of the people at amusement parks like hockey. --> Could be true. You have no idea.
B. Some of the people at amusement parks drove their car to the park --> Could be true. You have no idea.
C. Some people at amusement parks don't like roller coasters and funnel cakes. --> Must be false. The author sees ONLY two kinds of people at amusement parks. People at amusement parks can be divided into two groups: those who like roller coasters and those who like funnel cakes. So, there is no one that he meets who doesn't like both.
D. Atleast one person at amusement parks likes funnel cakes --> Must be true. Unless, this group doesn't show up to the park that day (meaning, the the park is filled with the other kind of people, those who like roller coasters...in which case, it is a could be true).
E. Atleast one person hates roller coasters --> Could be true, as he could be talking about a person who likes funnel cakes.

nye8870

@notwilliamwallace I especially like your concern for negation. By definition if something "must be true" then its negation will directly contradict the stimulus.