Lesson Three: Logical Reasoning & Logic Games Flashcards
–LOGICAL REASONING–
Rules for Approaching a Weaken Question:
- The stimulus will always contain an argument.
Weaken questions ask you to weaken the reasoning the author (or whoever) uses in the stimulus.
Using reasoning (premises) requires that reasoning to lead to a conclusion.
Thus, every weaken question will have an argument.
It’s your job to identify, isolate, and assess the premises and conclusion of the argument.
Rules for Approaching a Weaken Question:
- Focus on the Conclusion
Pay attention to the conclusion. Most weaken answer choices impact what’s said in the conclusion of an author’s argument.
If you know the conclusion, you’ll be able to better differentiate between correct, and incorrect answers.
Rules for Approaching a Weaken Question:
- Info in the stimulus is suspect.
Weaken questions are asking you to weaken the reasoning of the author.
The test wouldn’t ask you to weaken the reasoning of the author if it couldn’t be weakened.
The reasoning is prone to error, meaning there is error in the reasoning of the stimulus.
Read the argument carefully to find the error-prone reasoning.
Rules for Approaching a Weaken Question:
- Prephrase your Answers
Before diving into the answer choices, take time to speculate what you think the answer choices should look like.
This WILL save you time when choosing answers.
Rules for Approaching a Weaken Question:
- Answer choices w/ New Information can be accepted.
This isn’t like Must Be True / Main Point questions where new info isn’t allowed.
The point of Weaken questions is to choose the answer choice that will best weaken / undermine the reasoning in the stimulus, even if the answer uses new info.
Just because an answer choice uses new info doesn’t qualify it to be eliminated.
Typical Weaken Scenarios:
Most weaken questions in the LSAT occur when the stimulus uses…
1) Incomplete Information
2) Improper Comparison
3) Qualified Conclusion
1) Incomplete Information
When the author
- doesn’t account for all possibilities
OR
- relies on evidence that is incomplete
How do we combat Incomplete Information Question Stems?
- Introduce new possibilities (that went unaccounted for by the author).
- Introduce damaging information (that reveals how the information is incomplete)
- (e.g. omitted information)
2) Improper Comparison
when the author makes a comparison between things a efficiently/considerably similar.
3) Qualified Conclusion
when the author limits the conclusion in a way that leaves it open to attack.
Three Incorrect, yet Attractive, Answer TRAPS
- Opposite Answer
- Shell Game Answers
- Out of Scope Answers
- Opposite Answer
Directly opposes what the question stem is asking of you.
(i.e. if we’re dealing with weaken questions, then any answer that strengthens is an opposite answer).
- Shell Game Answer
Remember, the Shell Game tells us there are answer choices that are similar to what’s said in the stimulus but are slightly altered to be incorrect.
–> Use the Shell Game to eliminate answer choices that are similar but slightly tweaked to be incorrect.
- Out of Scope Answers
Answer choices that are unrelated to the information in the stimulus; information that is tangential.
Cause
event that causes another event to happen.
Effect
event that follows from the occurrence of another event.
The _____________ must _____________ come before the effect.
The _____________ must ______________ come at some point __________ the _______________.
cause; always; effect; always; after; the cause.
“Last week, Apple announced a quarterly deficit and the stock market dropped 10 points. Thus, Apple’s announcement must have caused the drop.”
Explain why the Cause and Effect reasoning is faulty/dubious.
There’s any number of different events that could’ve caused the drop in the stock market, that could be completely separate from Apple’s announcement.
i.e.
war,
nationwide economic downturn,
recession,
or no trading in the market
As you’ll see, no two events stated in the stimulus must share ______________, though that’s what the author is trying to tell you. It could be that there is a ____________ relationship between the variables, a ________________ relationship (not causal), or even ____________.
causality; spurious; correlational; chance
Causality Indicators (not limited to this list, just have a gist of what’s said here).
- caused by
- determined by
- produced by
- because of
- responsible for
- reason for
- leads to
- induced by
- promoted by
- product of
- played a role in
- was a factor in
- is an effect of
The author will oftentimes try to assert _________________ in the ________________ of an argument (based on the ________________).
causality; conclusion; premises
How to Attack Basic Causal Conclusions:
A. Find an Alternate Cause for the Stated Effect. (AC)
The author believes there is only one cause to the stated effect.
Choosing the answer that illustrates a new, alternate cause having the same stated effect will weaken the author’s conclusion.
How to Attack Basic Causal Conclusions:
B. Cause Without Effect (C w/o E)
The author believes stated cause leads to an effect.
Answer choice where stated effect occurs but effect doesn’t weakens author’s conclusion.
How to Attack Basic Causal Conclusions:
C. Effect Without Cause (E w/o C)
Author believes stated effect is a result of a given cause.
Answer choice where the effect happens without the occurrence of the cause weakens the author’s conclusion.
How to Attack Basic Causal Conclusions:
D. Show that the Stated Relationship is Reversed
Author believes relationship between stated cause and effect are true.
Answer choice that shows the stated effect is actually the cause and the stated cause is actually the effect weakens the author’s conclusion.
How to Attack Basic Causal Conclusions:
E. Show Statistical Problem w/ Data used to make Causal Conclusion
Author believes their conclusion follows from a set of data.
Answer choice that proves data invalid, proves the conclusion is invalid, weakening the author’s conclusion.
–LOGIC GAMES–
Linearity
positioning and ordering of variables.
Base
numbered set of variables (vertically or horizontally)
What would the horizontal and vertical base look like for the following example:
“Seven comics–Janet, Khan, Letitia, Ming, Neville, Olivia, and Paul–will perform in the finals of a comedy competition. During the evening of the competition, each comic, performing alone, will give exactly one performance.”
Horizontal
Base: J, K, L, M, N, O, P
1 2 3 4 5 6 7
Vertical
Base:
1 J
2 K
3 L
4 M
5 N
6 O
7 P
Explain a game in which you would need to use a vertical diagram, and one that requires a horizontal diagram.
Vertical: a game involving the floors to a building, or a hierarchy of some kind.
Horizontal: (ex.) houses positioned next to each other on a street.
Balanced v. Unbalanced Game
Balanced: number of variables = number of available slots.
Unbalanced: number of variables ≠ number of available slots.
Types of Unbalanced Games (2)
Underfunded Games
Overloaded Games
Underfunded
number of variables < number of available slots.
e.g. “There are 8 seats on the airplane (slots), but only 6 passengers (variables).
What do you do in a situation where you have empty slots in an underfunded game?
If you have empty slots, fill in a “placeholder variable” for them.
e.g. “E” in the two Empty slots.
Overloaded Games
number of variables > number of available slots.
e.g. “An employer is only taking 5 interviews this week, and there are 7 applicants.)
Not Law
Notates where a variable cannot be placed.
(Do this by writing the variable under the slot where it cannot placed and put a strike through it.)
“J cannot be first.”
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶J̶
Basic Blocks
Indicates adjoining variables.
“O comes immediately before P.”
┍━─┓
┃OP ┃
┗━─┛
Give the not laws for “O comes immediately before P.”
┍━─┓
┃OP ┃
┗━─┛
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶P̶ ̶O̶
If O comes immediately before P, then P can’t be first.
If P comes immediately after O, then O can’t be last.
Split Blocks
Indicates a certain number of spaces between variables.
Give the split block of “O is scheduled to perform two performances before P.” and its not laws.
┍━━━─┓
┃O____P ┃
┗━━━─┛
There is only one space between O and P in the block because there are exactly two performances before P, and O occupies one of them.
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶P̶ ̶P̶ ̶O̶ ̶O̶
Give the split block of “There are two performances between O’s performance and P’s performance” and its not laws.
┍━━━━━━━━─┓
┃O/P____ ____ P/O ┃
┗━━━━━━━━─┛
This is different from the prior not block, because here, there is NO SPECIFIED ORDER between O and P, it just says there exactly 2 performances between THEIR performances.
And having O one side of the slash and the other perfectly illustrates the two split blocks that are being accounted for in the above split blocks:
┍━━━━━─┓
┃P____ ____O ┃
┗━━━━━─┛
+
┍━━━━━─┓
┃O____ ____P ┃
┗━━━━━─┛
=
┍━━━━━━━━─┓
┃O/P____ ____ P/O ┃
┗━━━━━━━━─┛
Not laws
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶P̶ ̶P̶ ̶O̶ ̶O̶
Not Blocks
Indicates that variables cannot be adjoined.
ex. “O doesn’t come immediately before P.”
┍━─┓
┃ ̶O̶P̶ ┃
┗━─┛
(Outer restriction) O can never appear in the slot right before P.
If you want to diagram ________________, then your block has to be set up _________________.
┍━─┓
┃ O ┃
┃ P ┃
┗━─┛
1 ______ ̶P̶
2 ______
3 ______
4 ______
5 ______
6 ______
7 ______ ̶O̶
Sequencing Rules:
Sequencing Rules v. Block Rules
Sequencing rules place variables before and after others. Block rules specifies by how many places one variable is before another.
Sequencing Rules v. Block Rules
“O performs some time before P performs.”
Sequencing Rules: O–P
Block Rules: We don’t actually know how many spaces O is before P, but because we know O comes before P we can diagram Not Laws.
Not Laws:
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶P̶ ̶O̶
Sequencing Rules v. Block Rules
“O performs before P performs but after L performs.”
Sequencing Rules: L–O–P
Block Rules: We don’t know by how much L exist before O and before P, but we can diagram not laws.
Not Laws:
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶P̶ ̶P̶ ̶L̶ ̶O̶
̶O̶ ̶L̶
Sequencing Rules v. Block Rules
“L and O perform before P performs.”
Sequencing Rules:
L
∖
P
∕
O
Not Laws:
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶P̶ ̶P̶ ̶L̶
̶O̶
(VERIFY ALL SLOTS BEFORE JUST ASSUMING YOUR DONE DIAGRAMMING)
Dual Options
Indicates only two variables can occupy a given slot.
e.g. “Only L or J can be third place.”
Not Laws:
L/J \_\_\_ \_\_\_ \_\_\_\_\_ \_\_\_ \_\_\_ \_\_\_ \_\_\_ 1 2 3 4 5 6 7
Don’t right the ________ ___________ for ___________ ____________. It’s pretty self explanatory that the two variables can ONLY occupy a given spot.
not laws; dual option
Split Dual Options
Indicates that a variable can only occupy two slots
e.g. “L can either occupy 3rd or 5th.”
Not Laws:
L L
___ ___ ___ ___ ___ ___ ___
1 2 3 4 5 6 7
̶L̶ ̶L̶ ̶L̶ ̶L̶ ̶L̶
Circular Games
Games where a fixed number of variables are assigned to slots around a circle.
What’s a typical scenario in which you might receive a circular game?
People (variables) surrounding a table
Diagram the following (ON THE WHITEBOARD): “Eight individuals sit around a circular conference table w/ eight chairs. At most, one individual sits in each chair.”
You should always use ________________ to diagram, where at each end of the _____________ is a ______________. Diagramming where you draw a big ______________ and then any number of _____________ around not only is waste of time, but also makes it harder to decipher when variables are sitting at _____________ ends of the table.
spokes; spoke; variable; circle; variables; opposite
The only problem w/ using _____________ is that you may run into a scenario where there’s an ______ number of slots. Lucky for you, you know that if there’s an odd number of _________, then are no ___________ ends (____________ variables), there can’t be. But in any case, _______ as many ____________ as needed to solve the game. For instance the game says there are 8 seats at a table, then you need ______ spokes.
spokes; odd; slots; opposite; opposite; add; spokes; 4
Keep these rules in mind…
1) If there are rules governing ________________ (variables that sit exactly ____________ of each other), then fulfill those rules first, because they are the most ________________.
2) If there are no ______________ rules, then turn your attention to the _____________ rules, because they are the most ______________.
3) You can place variables in the diagram __________________ if you’ve satisfied / do not break opposite or block rules.
opposites; opposite; important; opposites; block; important; arbitrarily
Remember, in circular games, the variables are all seated in a _______________, meaning the __________ variable is ALWAYS seated right __________ to ___________ variable.
circle; first; next; last
In a circular game “To the left of” and “To the right of” refers to the left and right of a _____________, not ____________ left and right.
variable; YOUR
If there is a problem asking you for an accurate listing of the variables, REMEMBER the first variable in the list and the last one are ______________ right ___________ to each other.
ALWAYS; next
Some Local Questions will present a scenario where any given variable are right next to eachother, and if this is so, then what other variables can or can’t be next to eachother. In problems like these _________ _______________ to previous questions and based on the rules from your _____________ question, look at past ____________ and find the answer (revisit video if needed). This also means YOU MUST create a ________ diagram for every question.
GO BACK; current; diagrams; new
