Logical Reasoning

PT113 · S4 · Q22 The druid stones discovered in Ireland

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The druid stones discovered in Ireland are very, very old.

Conclusion (hence)

This stone must be more recent than "very, very old".

Evidence

The druid stones discovered in Ireland are very, very old. But this druid stone was discovered in Scotland.

Evaluate

This argument is so bad that it might be hard to figure out how to object. His argument was, Why not? Why can't Scotland have old stones?

It's not enough to just find the argument laughable. We have to be able to describe how the author got confused. Why did the author think that "being from Scotland" meant "recent / not old"?

When we're doing Flaw questions, we want to be on the lookout for the 10 famous flaws, since the argument is committing one of them about 40% of the time.

The most famous of the famous flaws is Necessary vs. Sufficient, in which the author supplies a conditional premise, but then uses that rule in an illegal backwards or negated way.

This argument feels like an illegal negation. When it comes to druid stones, we know that Discovered in Ireland → very, very old

If we made an argument that was an illegal negation of that rule, what would it sound like?This stone was Not-Discovered in Ireland. Therefore, it is Not very, very old.

That's how we're supposed to hear the author's premise to conclusion move.

Goal

Let's look for something complaining about the Necessary vs. Sufficient move, or something pointing out that

22.

The argument is flawed because it

  1. allows a key term to

    Not Equivocation

    This describes the famous Equivocation flaw, in which the author uses the same idea/concept twice, but in two different ways. Kevin's parents say he's a responsible person. Yet they claim he's not responsible for the recent arson. Well which is it, Kevin's parents? Is he responsible or not? This argument didn't have a key term with two different meanings. (Answers describing Equivocation, Circular, or Self-Contradiction are almost always wrong)

    3% picked this

  2. takes the fact that most

    Bad Evidence/Conclusion Match

    This answer almost feels like it's describing Sampling or Part to Whole (both famous flaws), but it's not quite saying either. Any time an answer describes a two part reasoning move, "takes the fact that X to constitute evidence that Y", we can ask ourselves whether X matches the evidence and whether Y matches the conclusion. Did the evidence say that "most members of a group have a certain property"? No. It said "all members of a group [druid stones discovered in Ireland] have a certain property [very old]". Does the conclusion say "all members of a group have a property"? No. It says "this stone has a property".

    10% picked this

  3. takes for granted the very

    Not Circular

    This describes the famous Circular reasoning flaw, in which the author's evidence restates the conclusion or presumes the truth of the conclusion. The conclusion is saying, "This Scottish druid stone is not super old." Does any premise say, "This Scottish druid stone is not super old"? No. So it's not circular. (Answers describing Equivocation, Circular, or Self-Contradiction are almost always wrong)

    5% picked this

  4. presumes without justification that what

    Not Temporal Flaw

    This describes a semi-famous flaw some people call Temporal Flaw: assuming that was was true in the past will be true again in the future. We can ask ourselves whether the author assumed this: If X was true about ? X will be true about group X before group X again That right side couldn't possibly match our conclusion, because the conclusion isn't about Group X. It's about one Scottish druid stone. The argument wasn't making any more from "in the past, X was true, so in the future X will again be true".

    3% picked this

  5. Correct

    takes the fact that all

    Why this is right

    Again, we have an answer describing a two-part reasoning move: takes the fact that X to constitute evidence that Y X needs to match our Evidence, and Y needs to match a Conclusion the author derived from that. Do we have a premise saying "all members of a group have a certain property"? Yes, "All members of group Irish druid stones have the property very old." Does the author then act like "member of group Irish druid stones are the only things that have the property very old"? Sure. When the author picks up that Scottish druid stone and thinks, "This is not an Irish druid stone. This stone doesn't belong to that group", he then reasons, "So this stone must not share that property of being very, very old. It must be of more recent vintage." This answer is technically still saying, "The author confused a Sufficient condition with a Necessary condition", but it's using disguised wording. "All members have it" is sufficient, whereas "members are the only ones that have it" is necessary.

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

    79% picked this

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