Logical Reasoning

PT14 · S2 · Q7 All zebras have stripes, and

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Conclusion (they must)

The stripes must serve as some sort of signal for other zebras.

Evidence (since)

They don't function as camouflage within the grasslands and yet ...

Intermediate Conclusion (must therefore)

... the stripes must be of importance to zebras.

Evidence (since)

All zebras have stripes. The most widespread species have the best stripes.

Evaluate / Goal

The question stem doesn't say we're strengthening an argument or reasoning, so we don't necessarily have to worry about premise and assumptions and such. Let's just get in there and find an answer that makes it more plausible that zebras' stripes have some signaling function for other zebras.

All zebras have stripes, and the most widespread subspecies has the best-defined stripes. The stripes must therefore be of importance to the species. Since among these grassland grazers the stripes can hardly function as camouflage, they must serve as some sort of signal for other zebras.

The subspecies of zebras with
No Impact
This reinforces the idea that stripes are correlated with being a successful zebra. but this does nothing to support the idea that stripes send some sort of signal to other zebras.
15% picked this
In certain tall grasses zebras
No Impact
This does nothing to support the idea that stripes send some sort of signal to other zebras. It's just saying that in some grasses, a zebra's stripes have some camouflage value, compared to having no coloration at all.
4% picked this
A visual signal transmitted among
Unclear Impact
This answer is lovably about signaling, but is it about stripes? Is it even about zebras? It would be a huge speculative leap for us to read this answer saying "a given species can have a visual signal that involves a temporary change of color" and think that this answer is telling us that zebras subtly change the color of their stripes to transmit a visual signal to fellow zebras.
16% picked this
Correct
Zebras react much faster to
Why this is right
This answer demonstrates that stripes have an effect on zebras. Since zebras perk up and pay attention to fast-moving striped shapes, that might be so they notice when their herd is suddenly running away from danger (or running to a food source). If the stripes were about camouflage, they likely wouldn't have any effect on fellow zebras, just their predators. The fact that stripes have this attention-getting effect on zebras means they probably send the signal, "Hey, pay attention to me. You're in this herd. We're moving to a different location. Come with." But even without us knowing specifically what signal the stripes send, we can still support the idea that stripes send a signal, because zebras clearly have heightened sensitivity to stripes.
Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.
65% picked this
Zebras have a richer repertoire
No Impact
The fact that zebras have lots of vocal signals makes it seem like they do indeed signal each other, so this very mildly strengthens the plausibility of the conclusion by establishing that. But "vocal signals" has no connection to "stripes". We're trying to find an answer that supports the idea that "stripes" signal something to other zebras.
0% picked this

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