Q20 - It would be wrong to conclude

[bermudask8er7]

Can you explain why B is correct and E is not? Thanks.

[bbirdwell]

A sharp translation of the argument will be a big help for this one.

C: If no evidence other than presence of bacteria --> wrong to conclude infection

p: if infected --> physically run down


(B) The key phrase is "on that basis alone." One way to translate it would be this:
C: no evidence other than 6 hrs of sun --> wrong to conclude bloom

p: if bloom --> 6 hrs sun + alkaline soil

(E) is close, but doesn't technically introduce a second factor like the original and (B) do (presence + run-down; sun + soil). It takes a one-time occurrence and asks for the same occurrence multiple times (high vs chronically high).
C: exceptionally high bp --> wrong to conclude hypertensive

p: hypertensive --> chronically high bp

See it?

[bermudask8er7]

Great explanation, thanks!

[jlz1202]

A sharp translation of the argument will be a big help for this one.

C: If no evidence other than presence of bacteria --> wrong to conclude infection

p: if infected --> physically run down


(B) The key phrase is "on that basis alone." One way to translate it would be this:
C: no evidence other than 6 hrs of sun --> wrong to conclude bloom

p: if bloom --> 6 hrs sun + alkaline soil

(E) is close, but doesn't technically introduce a second factor like the original and (B) do (presence + run-down; sun + soil). It takes a one-time occurrence and asks for the same occurrence multiple times (high vs chronically high).
C: exceptionally high bp --> wrong to conclude hypertensive

p: hypertensive --> chronically high bp

See it?

after reading your analysis I understand how to parallel both the premise and conclusion in this question. but another question comes to me:

"C: If no evidence other than presence of bacteria --> wrong to conclude infection

p: if infected --> physically run down"

so if A --> B, then not B --> not A,
therefore any C alone/ D alone / E alone cannot be the sufficient condition of A? then the sufficient condition of A has to be at least B+C/D/E?

I dont understand why a necessary condition of A can affect the sufficient condition of A? As my previous understanding and prep test LR practice seldom concerns both a necessary and sufficient condition of the same element.

thank you very much for help!

[tamwaiman]

"C: If no evidence other than presence of bacteria --> wrong to conclude infection

p: if infected --> physically run down"

so if A --> B, then not B --> not A,

At first I made the same mistake with you. But wait! The opposition of lacking the evident except for presence of bacteria is not "physically run down". These are different issues, so your B/~B is not applicable.

[anjelica.grace]

How would one know that because a condition is not sufficient, it is therefore necessary?

I see how both the stimulus and the correct answer choice has this additional necessary requirement theme going on, but I don't see "also" or a term indicating that the first condition is necessary as well.

When I prephrased the stimulus, I got:

Bacilli is not sufficient for Strep infection because run-down host is necessary.

Is there an implied necessity assigned to bacilli?

Sorry if my question is confusing.

[jgallorealestate]

@anjelica.grace

Very interesting point.

"Is there an implied necessity assigned to bacilli?"

Yes. To get strep throat, you need strep bacilli and a run down host. Both are necessary.

"It would be wrong to conclude that a person has Strep infection if there is evidence to the fact that strep bacilli are present." Why? "Because they need a run down host." So what do they need? 2 things: strep bacilli and a run down host

The passage could have ended, "infection does not occur unless the host is physically run down AS WELL as bacilli." But how could you get a Streptococcus infection with only a run down host? We have to assume that it requires both.

Here is why B is right.

I didn't pick B because it has 2 conditions required and the passage didn't appear to have 2 conditions required either. What conditions? the passage requires: bacilli and a run down host

B is the only answer that has 2 requirements: "both 6+ hrs of sunlight AND alkaline soil to bloom."

And the passage requires: bacilli and a run down host.

No other answers require 2 things.

[brianabbott1987]

The Stim

c: bacilli -> /infection
p: infection -> bacilli AND physically run down

c: A -> /B
p: B -> A and C

Note: The host being physically run down is like the floodgate for infection to occur. What the stim is saying is bacteria isn't enough to conclude infection because infection won't actually occur until the host is rundown.

Logically there must be a rundown host and bacilli. Note the use of no other evidence than the fact that bacilli are present.

This question tests your ability to recognize that and I didn't recognize it and chose E.

Answer choice B

c: receives 6 or more hours -> /bloom
p: bloom -> receives 6 or more hours AND slightly alkaline soil

This translates to
c: A->/B
p: B->A and C

Answer choice E

c: high reading for blood pressure (single reading) ->/hypertensive
p: hypertensive -> chronically high blood pressure (multiple readings)

This translates to
c: A->/B
p: B->C

[AliceInWonderland]

Here's my way of seeing why B is correct but E is not. Let me know if this doesn't make sense!

Stimulus: [X: bacilli present in throat] -X-> [C: person has infection]; [C: person has infection] --> [Y: host is physically run down]
B: [X: six or more hours of direct sunlight each day] -X-> [C: lavender will bloom]; [C: lavender will bloom] --> [Y: six or more hours of sunlight per day and slightly alkaline soil]
E: [X: a high reading for blood pressure that is exceptional for that person] -X-> [C: person is hypertensive]; [C: person is hypertensive] --> [Y: chronically high blood pressure]

All above are of the form "From X alone, we cannot conclude C; C requires Y." However, both the stimulus and B satisfy Y --> X (if we assume that bacilli must be present in throat before it can be physically run down and if we ignore the difference between "direct sunlight" and "sunlight"), but E does not satisfy Y --> X. For example, say the range of normal blood pressure is 1-10 (making up numbers here just for illustration), and Alice's blood pressure readings are always somewhere between 20 and 22, then even though Alice does have chronically high blood pressure, none of the readings of Alice's blood pressure is exceptionally high *for her*.