Conditional reasoning Flashcards

Question

# What is the numerical estimate? All

Answer 1

1-100 (at least one)

Answer 2

0-99 (Not all) ## Footnote ie at least 1 is not

Answer 3

> 50% (majority)

Answer 4

< 50% (minority)

Answer 5

means that the relationship between the two variables has exactly the same meaning regardless of which “side” of the relationship is the starting point of your analysis.

Answer 6

**False** ## Footnote no single arrow is reversible. but we can infer that some B's are A's

Answer 7

Double arrow < ------> Double-not (None) <----/-----> some (some)

Answer 8

all ------> most ----->

Answer 9

**False** we know that some A’s are not B’s. Correctly reversed, the relationship reads, “Some things that are not B are A’s.” B/ some A ✅ | Key: "Some" do not have contrapositive, but they are reversible ## Footnote Thus, you can reverse a some are not statement, but you must be careful when doing so in order to avoid accidentally moving the “not.”

Answer 10

H/ some G ## Footnote Thus, you can reverse a some are not statement, but you must be careful when doing so in order to avoid accidentally moving the “not.”

Answer 11

This statement is irreversible

Answer 12

**True** ## Footnote This is an additive inference, so-called because it comes from “adding” two statements together to make the inference.

Answer 13

**True** ## Footnote This is an inherent inference: inferences that are known to be true simply from the relationship between the two variables.

Answer 14

All ---> Most ----> Some | Deals only with positive terms ## Footnote if you have an all relationship, you automatically know that the most and some relationships for that same statement are true. So, if a statement is made that “All waiters like wine,” then you immediately know that “Most waiters like wine,” and “Some waiters like wine.” If “Most waiters like wine,” then you automatically know that “Some waiters like wine.”

Answer 15

**False** ## Footnote But, because "most" is below "all" on the Logic Ladder, you do not know with certainty that “All waiters like wine” (it is possibly true, but not known for certain). This reveals a truth about the Logic Ladder: the upper rungs automatically imply the lower rungs, but the lower rungs do not automatically imply the upper rungs. In other words, as you go down the rungs the lower relationships must be true, but as you go up the rungs the higher relationships might be true but are not certain.

Answer 16

**True** ## Footnote from the Logic Ladder we know that “Some doctors are lawyers.” And, because some is a reversible term, we then know that “Some lawyers are doctors.” The presence of inherent inferences in non-reversible terms such as all and most helps to make complex inferences easier to follow.

Answer 17

* Most of A is P * Most of P is A * A some P ## Footnote This is a very tricky problem. Because the arrow between AFR and RP goes in both directions, we can infer that the most relationships are inherent in both directions.

Answer 18

None ---> Most are not -----> Some are not ## Footnote This is the logic ladder for negative terms So, if a statement is made that “None of the waiters like wine,” then you immediately know that “Most waiters do not like wine,” and “Some waiters do not like wine.” just as in the positive Logic Ladder, in the negative Logic Ladder the upper rungs automatically imply the lower rungs, but the lower rungs do not automatically imply the upper rungs.

Answer 19

**Always combine common terms** *A some B, B ----> C = A some B -----> C* ## Footnote therefore , A some C.

Answer 20

True ## Footnote if a sufficient condition occurs, you automatically know that the necessary condition also occurs. If a necessary condition occurs, then it is possible but not certain that the sufficient condition will occur.

Answer 21

1. the sufficient condition does not actively cause the necessary condition to happen. Instead, the occurrence of the sufficient condition is a sign or indicator that the necessary condition will occur, is occurring, or has already occurred. In 2. Temporally speaking, either condition can occur first, or the two conditions can occur at the same time. 3. The conditional relationship stated by the author does not have to reflect reality. Your job is not to figure out what sounds reasonable, but rather to perfectly capture the meaning of the author’s sentence.

Answer 22

Stem: A ---> S 1. A ------> S ✅ - repeat inference 2. S ------> A ❌ - Mistaken reversal 3. A/ ----->S/ ❌ - Mistaken negation 4. S/ ----->A/ ✅ - Contrapositive of stem ## Footnote Remember A ---->S is not reversible But for A ----S > we can derive a contrapositive, which states that when the necessary condition fails to occur, then the sufficient condition cannot occur.

Answer 23

simply reverse and negate the two terms.

Answer 24

B/ ------> A/

Answer 25

**True** ## Footnote the second is a contrapositive of the first, which states that because D occured, C did not occur.

Answer 26

* If * When * Whenever * Every * All * Any * People who ... * In order to ... * To get ... * No * None

Answer 27

* Then * Only * Only if * Must * Required * Unless * Except * Until * Without

Answer 28

**Unless Equation** is applied to the diagram: 1. Whatever term is modified by “**unless**,” “**except**,” “**until**,” or “**without**” **becomes the necessary condition**. 2. The **remaining term** is **negated** and **becomes the sufficient** condition. Since “unless” modifies “a person studies,” “Study” becomes the necessary condition. The remainder, “he or she will not receive an A+,” is negated by dropping the “not” and becomes “he or she will receive an A+.” Thus, the sufficient condition is “A+,” and the diagram is as follows: **A+ -------> S**

Answer 29

S -----> PC The term “**when**” typically introduces a **sufficient condition**, and so “sun goes down” is the sufficient condition. where a word such as “**if**” or “**when**” **appears in the second half of a sentence** it **introduces the sufficient condition** — the first part of the stimulus is the **necessary condition**. ## Footnote The fastest approach is a mechanistic one: observe the form of the problem by identifying the indicators (like “when”), then diagram the problem using those as your guides. Only resort to weighing the merits of each condition if no indicators are present to assist you. In this way you can avoid over-thinking a problem and introducing errors into the system.

Answer 30

This is another tricky problem. As usual, “**only**” introduces the **necessary** condition, but the test makers use a deceptive device: in this sentence “only” modifies “way,” and the “only way” refers to working hard. Thus, “work hard” is in fact the necessary condition. **This type of construction appears with enough frequency that you should be familiar with it**

Answer 31

C ----> DV/ ## Footnote You should convert to am if /then statement

Answer 32

look for a contrapositive or a repeat form in the answer choices. This may be the correct answer ## Footnote avoid mistaken reversals or mistaken negation, which are contrapositives of each other.

Answer 33

1. Mistaken reversal 2. Mistaken negation 3. Exagerated (out of scope) ## Footnote When considering the likelihood that one of two possible answers will appear, you can expect that the test makers will typically choose the answer that requires the most work to reach the correct answer.

Answer 34

“**at least one** of the two, possibly both.” ## Footnote In its everyday use outside of the LSAT, “either/ or” has come to mean “one or the other, but not both,” but this usage is incorrect on the LSAT.

Answer 35

John--------> Jack/ or Jack ---------> John/ ## Footnote Note: second diagram is the contrapositive of the first diagram The diagrams reflect the fact that if one of the two fails to attend, then the other must attend in order to satisfy the “at least one of the two” condition imposed by the “either/or” term. Note that neither of these two diagrams preclude both John and Jack from attending the party. Meaning it is possible that both also attend.

Answer 36

Cindy -------> Clarice/ Clarice ------ > Cindy/ cindy <--/-->clarice ## Footnote Note: both cannot occur together here because the passage clarified this

Answer 37

**False** Not smart **or** Not resourceful -------> Not graduate *In this case, if either one of the two necessary conditions is not met, then you cannot graduate* ## Footnote Whenever you take a contrapositive of a statement with multiple terms in the sufficient or necessary condition, “and” turns into “or,” and “or” turns into “and.”

Answer 38

Not smart **and** not resourcefull ---------> not graduate ## Footnote note that as the contrapositive occurred the “or” joining the original necessary conditions changed to “and.”

Answer 39

Not happy -----> not rich or not famous

Answer 40

1. “A if B” B ------> A 2. “A only if B” A --------> B 3. A <--------> B

Answer 41

1. A and B both occur 2. Neither A nor B occur A/ <-------> B/ | Remember: double arrow is reversible ## Footnote In double arrow: Any scenario where one of the two attends occurs but the other does not is impossible.

Answer 42

JW ---------> KW/ KW ----------> JW/ ## Footnote Depending on the type of election, there may or may not be only one “winner” of the election. Look for CLUES in the passage to determine if there is a posibility of both occuring

Answer 43

"Until" is the time condition of "unless." Because "until" indicates a time condition (before/after), there cannot be a simultaneous occurrence between the necessary and sufficient condition.

Answer 44

**False** if A → B and C, that doesn’t mean that if B → C.

Answer 45

* A &B → C/ * C → A/ or B/ Because both cannot occur together, we use the ←/→ that indicates that 2 items cannot occur together i.e. when one is +ve(occurs), the other is -ve (cannot occur). We also know the ←/→ is reversible Therefore; * A&B ←/→ C Inferrences; * if A and B occured, then C must not occur * if C did not occur, then A and B must occur * if C occured, then A/ or B/ . ie atleast one out of the 2 did not occur, possibly both did not occur. * If A/ , C occured * If B/ , C occured

Answer 46

Firstly contrapositive - C ←/→ A/ or B/ A. if C happened, then A did not happen ❌ Reason: The necessary condition is not dependednt only on absence of A alone. It is possible that B was absent instead while A was present. The correct answer should have been "either A was absent or B was Absent. In other words, atleast one of the two (A or B) was absent" B. If C happened, then B did not happen ❌ Reason: same as A C. If A happened, then C happened ❌ Reason: Mistaken negation D. If B happened, then C happened ❌ Reason: Mistaken negation E. If A did not happen, then C happened ✅ Reason: we need at least one not to happen as a necessary condition for C to occur F. If B did not happen, then C happened ✅ Reason: we need at least one not to happen as a necessary condition for C to occur G. If C happened, then both did not happen ❌ Reason: either or means at least one, possibly both H. If C happened, then Either A or B did not happen, possibly both did not happen ✅ Reason- A paraphrase of the exact contrapositive.

Conditional reasoning Flashcards

(73 cards)