Logical Reasoning

PT118 · S1 · Q21 Although the geological record contains

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Although the geological record contains some hints of major meteor impacts preceding mass extinctions, there were many extinctions that did not follow any known major meteor impacts.

Conclusion (Thus / this suggests that)

There is no consistent causal link between major meteor impacts and mass extinctions.

Evidence

Many mass extinctions did not follow any known major meteor impact. Many major impacts were not followed by mass extinctions.

Evaluate

The author is trying to establish that . How do we prove that "there is no consistent causal link" between two things? Did the evidence provide that sort of proving mechanism?

No. So, since we have this New Wording in the conclusion, "no consistent causal link", we know that the correct answer will have to give us some rule that outputs "no consistent causal link" on the right side of the conditional arrow.

Our evidence is that the association between X and Y is splotchy. Many Y's didn't come after some X had occurred. And many X's occurred without a Y happening afterwards.

Goal

We primarily want to look for a rule that proves the wording "no consistent causal link". When we find an answer offering such a rule, we'll check out its trigger and see if our evidence clearly applies to the trigger. Maybe an answer will sound something like

If major meteor impacts Then there is no and mass extinctions → consistent causal occur many times w/o link between them the other occurring

21.

Which one of the following assumptions enables the argument's conclusion to be properly inferred?

  1. Correct

    If there were a consistent

    Why this is right

    When we see "If [conclusion]", it's automatically wrong (because the conclusion needs to be on the right side of the arrow, but if conditions go on the left). But seeing "If [anti-conclusion]" is totally fine, or similarly "[Anti-conclusion] only if" is totally fine. Why? Because when we contrapose those, we'll have the conclusion on the right side (correct answers love to disguise themselves in contrapositive form). Here's the contrapositive of this answer choice: If some major meteor Then there is impacts are NOT → NOT a consistent followed by mass causal link between extinctions MMI's and ME's From our evidence, can we trigger the left side? Sure. We were told that some major meteor impacts are not followed by mass extinctions. According to this rule, then, there is no consistent causal link between major meteor impacts and mass extinctions. Combining this answer with our evidence allows us to logically derive the conclusion.

    Skill tested: Sufficient Assumption · how this choice captures the argument's function is the move to repeat next time.

    57% picked this

  2. Major meteor impacts and mass

    Bad Trigger Match

    This is offering a rule about "consistent causal link", so it's worth considering. When we see "unless" we put a negated version of one of the two conditions on the left the arrow. Since we want the right side of the arrow to match our argument's conclusion, we'll negate the 2nd idea in this answer and throw it on the left side of the arrow. It is not the case that Major meteor impacts many mass extinctions → and mass extinctions have followed major cannot be consistently meteor impacts causally linked The right side matches our conclusion. Does our evidence trigger the left side? Were we told that "almost no" mass extinctions ever follow major meteor impacts? No we were not. We were told that in many cases mass extinctions have not followed meteor impacts, but we weren't told there are "not many" cases where mass extinctions have followed impacts. Many doesn't have an official minimum, but we can think of it being something like "at least 10". When we negate many (and get not many), the best rephrase would be almost none. If I say "many of my friends have been to New York City" and you say, "That's not true", you're not committing to the idea that "NONE of my friends have been to NYC, just that I don't have many friends who have gone". So if you disagree with my statement, you're saying, "Not true. None (or almost none) of your friends have been to NYC." Thus, the trigger of this conditional (once we negate the quantity many) is saying, "If almost no mass extinctions have followed major meteor impacts, then ...". And we don't have any information to trigger that rule.

    28% picked this

  3. Of the mass extinctions that

    Unrelated to Goal

    We don't need to read this answer, since it's not providing a rule that outputs the language "no consistent causal link". We won't be able to derive a conclusion that says "no consistent causal link" if we never use that term in our evidence or our Sufficient Assumption.

    5% picked this

  4. If there is no consistent

    If-Conclusion Reversed Logic

    As soon as we see that the wording of the Conclusion is showing up as the If (left side) condition, we know this one is hopeless. "If Conclusion is true" is always wrong on LSAT. Remember, "If Conclusion is false" is fine (aka, "If Anti-Conclusion is true"). That contraposes into having the conclusion on the right side of the arrow. On Sufficient Assumption, they usually disguise the linking idea we want by writing it in contrapositive form. And they usually trap us into picking a mistaken reversal or negation of the linking idea we want. Conclusions have to match the right side of principles / rules being used to derive them.

    8% picked this

  5. There could be a consistent

    Weakens

    This answer actually says, "even if the PREMISE is true, the CONCLUSION could be false". That hurts the author's argument, whereas our job is to fully prove the argument.

    1% picked this

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