Q17 - Humankind would not have survived

[ohthatpatrick]

Question Type:
Match the Reasoning

Stimulus Breakdown:
Conclusion: Our ancestors were at least partially altruistic.
Evidence: Humankind couldn't have survived as it has if ancestors hadn't been motivated by sacrificing themselves for the survival of their kin. This type of sacrificing is a form of altruism.

Answer Anticipation:
This is sound logic. We know humankind survived. We know that this survival guarantees that our ancestors were motivated by a desire to sacrifice themselves for their kin. We know that this sacrifice is a form of altruism. So it's fair to say our ancestors were partially altruistic. Symbolically, we need something like:

X wouldn't have happened unless A had trait B.
Trait B counts as having trait C.
Since X did happen, we know that A had trait C.

Or

Survival ---requires---> sacrifice ---requires----> altruism.
Survival happened.
So altruism happened.

We can start by looking for a chain of three ingredients. Then we just need a fact to trigger the start of the chain, and we'll conclude the end of the chain.

Correct Answer:
A

Answer Choice Analysis:
(A) Chain of 3? Raising grades ---> spending more time --> good time management. Some students do raise grades, so some students do have good time management. Looks good!

(B) Chain of 3? Nope. There's only one conditional in the evidence

(C) Chain of 3? Nope. There's only one conditional in the evidence

(D) Chain of 3? Avoiding depletion of resources --> alternative materials --> requires more power. But that last link wasn't really conditional. It said replacing with alternative materials "generally" requires more power. Also, the conclusion doesn't match the end of the chain.

(E) Chain of 3? Harmonizing with surroundings -> well designed -> expensive to construct. But the conclusion here is an either/or claim.

Takeaway/Pattern: The original argument doesn't scream out "chain of 3 ideas", but the conditional word "if" in the first sentence can prompt us to start thinking that way. In terms of looking for quick conclusion mismatches, the original argument's conclusion was a watered down factual claim. (A)'s conclusion matches. (B)'s is broader/stronger. (C) is a conditional conclusion. (D) is a statement about the future. (E) is an either/or.

#officialexplanation

[kitmitzi]

I did not understand how to do the formal logic diagram on this. I had it down to A or D, but ended up picking the wrong answer (D) because it mirrored the original more in wording (both use "but since").

Can anyone explain how A is similar to the original stimulus?

[danitay]

I dunno if this is even close or not, but I had something like this:

Ancestors motivated by desire to sacrifice (MDS)
Humankind survive (HS)
Altruism (A)

premises:

~MDS --> ~HS (or HS --> MDS)
MDS --> A
Conclusion: Since we know HS, HS --> MDS--> A.

In answer A, the premises are:

Raise grades (RG)
Increase time studying (IT)
Manage time well (MT)

~IT --> ~RG (RG---> IT)
IT --> MT
Conclusion: Since we know RG, RG --> IT --> MT.

[bbirdwell]

Looks good Danitay!

[irini101]

I am confused by why not translating "when doing so...ensure...survival..."? (sacrifice--> survival) It seems also conveys formal logic.

I diagram as follows:

premise: ~sacrifice --> ~survive
sacrifice --> survive (therefore sacrifice <--> survive)
conclusion: sacrifice --> altru

therefore summing up the train would be:

sacrifice --> altru
sacrifice <--> survive

Then I find no answer matches the pattern. Could anyone please point out the flaw in the diagram above? Thanks a lot!

[bbirdwell]

I actually find diagramming this one out to be a bit cumbersome, and not necessary for finding the answer. Try to save time and make smart eliminations in situations like this BEFORE you get wrapped up in a confusing diagram.

What's the conclusion?
ancestors were PARTIALLY altruistic.

Notice the "weak" nature of the conclusion.

Now, look at the conclusions for the others answers:
(A) SOME students manage time well.
Sounds pretty good.

(B) MUST be incapable.
Too strong.

(C) Not even close.

(D) WILL become depleted.
Too strong.

(E) EITHER...OR
Not even close.

How easy was that?

The "when" statement makes this one complicated to diagram. You've erred in your diagram by making it a separate and independent statement, which it is not. It's just a qualifier to the first one.

The first one:
~sacrifice --> ~survive

The "when" statement adds flavor to the first (unnecessary complication):
~sacrifice (when it would help others survive) --> ~survive

Next statement:
sacrifice (when it would help others survive) --> altruistic

So, simply contrapose the first one so that we have a chain of logic:
survive --> sacrifice (when it would help) --> altruistic

We know that humanity has survived (first sentence), so we can conclude, as the argument does that at least SOME were altruistic.

(A) matches this perfectly:

~increase study --> ~raise grades
increase study --> time management
raise grades --> increase study --> time management

[chike_eze]

@Brian, I've heard about this strategy before -- eliminating based on the structure of the conclusion.

Question: How often do you use this to quickly eliminate choices on the real thing? These matching questions take me forever! I usually skip them when I'm not doing good with time.

Any tips on how I can improve my timing? (I think on average I spend 2 - 2:30 mins on matching questions - especially match reasoning questions).

[ohthatpatrick]

Hey, there. Brian's off making the world a better place, but I'll try to field the question, as I also use that shortcut when possible.

The keywords there were "when possible". That's how often we use it.

On some questions, it can literally be the only thing you look at and it will get you all the way to the correct answer. On other questions, it will only get rid of one (or even no) answer choice.

The cool thing is that almost all matching questions use obvious argument keywords to help you find the conclusion without reading through the whole answer choice. They'll either use conclusion triggers such as "hence, thus, so, therefore" to signify the conclusion, or they'll use premise triggers such as "because, since, after all, for" which indirectly tell us where to find the conclusion (whatever idea is being supported by those premises is the conclusion).

So on average, I'd say focusing on the type and strength of claim in the conclusion allows us to eliminate 2 or 3 answer choices without having to spend the time to read through them and think about their logic.

Overall, on these Matching questions, it often pays to funnel the specificity of what you're looking for from general characteristics down to more nuanced (if needed).

So we might start by screening out answers with totally different types of conclusions. Then we might screen out answers that don't have the same number or type of premise ingredients (for example: if the original argument has two conditional premises, then we can often just skim an answer choice to check whether it also has two conditional premises). Once we get down to the last two or three (if we haven't already got to an answer by then), then we start to really go part by part to match up the logic with the original.

Let's talk for a sec about what we mean by "type" and "strength" of conclusion.

There are a few different "types" of conclusions that help me characterize what I'm looking at:
1. Conditional (i.e. "Thus, if humans survive, we know that they're altruistic")
2. Comparative (i.e. "Hence, humans are more altruistic than other mammals")
3. Absolute (i.e. "So, some humans are altruistic")
4. Either/or (i.e. "Therefore, either humans are altruistic or altruism isn't required for survival")

There are a few different "strengths" of conclusion:
1. Conditional (if, then, when, requires, necessitates, always, never, all, each, any, every, only, only if, etc.)
2. Majority (most, usually, probably, tends to, normally, typically, generally, likely)
3. Some (some, sometimes, not all, not always, could, may, might)

One final suggestion for trimming down your time on Matching questions is to experiment with being more aggressive about picking the first answer that really gels well with what you were looking for. For instance, in this question, (A) completely satisfied the recipe we were looking for. Let's trust our work, circle the problem number so that we can return to this problem if we have leftover time in this LR section, but otherwise move on.

As you may be thinking, the success of this strategy really hinges on the confidence with which you initially diagnose the type/strength of your premise ingredients, the type/strength of your conclusion, and the logical ordering of how they fit together. So the better you get at abstracting the original argument into a quick recipe of ingredients, the more confident you'll be picking an answer (without seeing all of them) and moving on, convinced that the answer matches up with your list of ingredients.

Let me know if this elicits further questions.

[tzyc]

So the 2nd conditional statement in the stimulus is "since even this kind of...is a form of altruism"?? Sometimes I forget "is" can be a conditional statement...does "is" always lead to conditional statement...??
Thank you

[ManhattanPrepLSAT1]

Hey tz_strawberry, you really want to be careful about trying to make blanket rules that are "always" true. The LSAT is really good and creating new instances that seem to violate rules like that.

However, "is," "are," "were," etc... do establish conditionals. But only use them when you think it's absolutely appropriate; the right kind of question, the right location in the section, other statements that seem to imply conditionals, similar terms that indicate a connection between statements, etc.

Examples:

Apples are delicious.
A --> D

Being articulate is appreciated.
Art --> Apr

The dogs were ferocious.
D --> F

[donghai819]

Hey guys, just a side note here:

The "even" in the last sentence in the stimulus corresponds to the "do " in the second last sentence in the answer choice A.

[JosephV]

Hey tz_strawberry, you really want to be careful about trying to make blanket rules that are "always" true. The LSAT is really good and creating new instances that seem to violate rules like that.

However, "is," "are," "were," etc... do establish conditionals. But only use them when you think it's absolutely appropriate; the right kind of question, the right location in the section, other statements that seem to imply conditionals, similar terms that indicate a connection between statements, etc.

Examples:

Apples are delicious.
A --> D

Being articulate is appreciated.
Art --> Apr

The dogs were ferocious.
D --> F

Hi,

Could somebody, please, give examples when "to be" could be thought of as being used in a conditional sense but is not? Thanks.

[ohthatpatrick]

Patrick is responding to this post.

There were Raiders fans at the party last night.

I will be ready for another cup of coffee later.



All of these COULD still be represented as conditionals, but they seem more like narrow facts than they seem like
RULES
GUARANTEES
REQUIREMENTS
UNIVERSALS

[VickX462]

Question Type:
Match the Reasoning

Stimulus Breakdown:
Conclusion: Our ancestors were at least partially altruistic.
Evidence: Humankind couldn't have survived as it has if ancestors hadn't been motivated by sacrificing themselves for the survival of their kin. This type of sacrificing is a form of altruism.

Answer Anticipation:
This is sound logic. We know humankind survived. We know that this survival guarantees that our ancestors were motivated by a desire to sacrifice themselves for their kin. We know that this sacrifice is a form of altruism. So it's fair to say our ancestors were partially altruistic. Symbolically, we need something like:

X wouldn't have happened unless A had trait B.
Trait B counts as having trait C.
Since X did happen, we know that A had trait C.

Or

Survival ---requires---> sacrifice ---requires----> altruism.
Survival happened.
So altruism happened.

We can start by looking for a chain of three ingredients. Then we just need a fact to trigger the start of the chain, and we'll conclude the end of the chain.

Correct Answer:
A

Answer Choice Analysis:
(A) Chain of 3? Raising grades ---> spending more time --> good time management. Some students do raise grades, so some students do have good time management. Looks good!

(B) Chain of 3? Nope. There's only one conditional in the evidence

(C) Chain of 3? Nope. There's only one conditional in the evidence

(D) Chain of 3? Avoiding depletion of resources --> alternative materials --> requires more power. But that last link wasn't really conditional. It said replacing with alternative materials "generally" requires more power. Also, the conclusion doesn't match the end of the chain.

(E) Chain of 3? Harmonizing with surroundings -> well designed -> expensive to construct. But the conclusion here is an either/or claim.

Takeaway/Pattern: The original argument doesn't scream out "chain of 3 ideas", but the conditional word "if" in the first sentence can prompt us to start thinking that way. In terms of looking for quick conclusion mismatches, the original argument's conclusion was a watered down factual claim. (A)'s conclusion matches. (B)'s is broader/stronger. (C) is a conditional conclusion. (D) is a statement about the future. (E) is an either/or.

#officialexplanation

Can you explain why there is a "chain of three?" As I see it there are only 2 premises. I eliminated A in my first pass due to premise number mismatch.

Thanks!

[ohthatpatrick]

Yeah, you're right, two premises involved in making the "Chain of 3".
But there's a third premise, the fact that "humankind clearly has survived".

By "chain of 3", I didn't mean there were three premises.

Premise 1:
A --> B

Premise 2:
B --> C

Chain of 3 is just putting those together:
A --> B ---> C

In this case,
Premise 1:
Survival ---> Self-Sacrifice

Premise 2:
Self-Sacrifice --> Altruism

Chain of 3 when we put that together:
Survival --> Self-Sacrifice --> Altruism

But by providing us with the fact that "Humankind clearly has survived", the author is allowed to draw the factual conclusion that "there was altruism".


Consider this purely hypothetical argument, where the conclusion is not guaranteed.

Anyone who beats the Ninja warrior course will get a sponsorship from Keds, and all sponsorships from Keds come with a giant shoe-shaped cake. Thus, someone has at some point received a giant shoe-shaped cake.

This is invalid logic, because we don't know whether anyone has ever beaten the Ninja warrior course. We don't know whether anyone has ever received a sponsorship from Keds.

Here's an adjusted version of that argument that packages in the 3rd premise (the fact):
Anyone who beats the Ninja warrior course, as Lenny heroically did, will get a sponsorship from Keds, and all sponsorships from Keds come with a giant shoe-shaped cake. Thus, someone has at some point received a giant shoe-shaped cake.

This was valid logic, because we know that Kenny beat the course, got the sponsorship, got the cake.

Hope this helps.