Logical Reasoning

PT106 · S2 · Q18 Dobson: Some historians claim that

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Dobson: Some historians claim that the people who built a ring of stones thousands of years ago in Britain were knowledgeable about celestial events.

Conclusion (Therefore)

The people who built the ring were not knowledgeable about celestial events.

Evidence

Some people thought the ring-builders were knowledgeable because two of the stones form a line that points to the sun at sunrise at the spring equinox.

But given the number of stones in the ring, there's a significant probability that at least one pair of them will form a line that points to something celestially significant.

Evaluate

As we look at the Support for the claim that the ring-builders were not knowledgeable about celestial events, we see that it really begins with

That's a bad sign, when it comes to this author's logic. You're not allowed to make your case that "X is false" by telling me about the people who believe "X is true".

It looks like a setup for the famous Unproven vs. Proven False flaw.

We can't say,

Maybe I believed that Sally can speak French for a silly reason (she loves croissants). Calling out the stupidity of my assumption that "croissant lovers all speak French" is very different from proving that Sally can't speak French.

That's what this author is doing. She is saying,

But even though the historians had a silly reason for believing the ring-builders were knowledgeable, that doesn't prove that the ring-builders weren't knowledgeable (there might be a non-silly reason to believe they did have knowledge of celestial events).

Goal

We either want to find an answer describing this famous Unproven vs. Proven False flaw, or we want to otherwise find an answer making the objection that,

18.

Which one of the following is an error of reasoning in Dobson's argument?

  1. Correct

    The failure of cited evidence

    Why this is right

    This is one way to phrase the Unproven vs. Proven False flaw (other ways sound like, "treats a failure to prove as proof of failure" or "takes an absence of evidence as evidence of absence"). The cited evidence is the 2nd sentence: "the ground for this claim [that the ring-builders are knowledgeable] is that two stones point somewhere interesting". The author rebuts the logical force of that premise saying, "however, if you take any bunch of rocks that are randomly strewn about, there is still a large change that you can find two of them that end up pointing at something celestially interesting". The correct conclusion for the author to draw at this point should sound more undecided, more agnostic: - Thus, it would be premature to conclude that the ring-builders were knowledgeable about celestial events. - Thus, we'll need more compelling evidence before we believe the historians' claim. The author is not allowed to just assume the historians conclusion is a false claim, just because they supported it poorly. Whenever we're doing Flaw and we see that the author is rebutting someone else, we want to be on guard for two famous flaws: Ad Hominem (the author rejects their position because of their ulterior motive or past behavior) Unproven vs. Proven False (the author shoots down someone's rationale and then concludes the polar opposite of their original conclusion)

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

    62% picked this

  2. Dobson’s conclusion logically contradicts some

    Wrong Flaw: not Self-Contradiction

    This describes another one of the ten famous flaws: Internal Contradiction. Dobson only has one piece of evidence, the 2nd to last sentence. It certainly does not contradict the conclusion in the final sentence. A contradiction would sound like: There are many stones, so the chance at least one pair points somewhere interesting is large. Therefore, it's very unlikely that any pair of stones would point somewhere interesting by random chance.

    13% picked this

  3. Statements that absolutely establish Dobson’s

    Never a Flaw Reversed Ingredients

    This answer would be closer to describing reality if we reversed the order of ingredients: statements that merely give some support are treated as if they absolutely establish the conclusion. That would be similar to the semi-famous flaw Possible vs. Certain. It's bad to go overboard in the conclusion. If we establish that Karl is sniffling a lot and blowing his nose a lot, that supports the idea that he's sick, but it would be flawed to say "Thus, he is definitely sick". However, this answer choice is complaining that an author ended up saying a conclusion that is weaker than what we could have. Not only did that not happen here, but that wouldn't be a flaw even if it did happen. If we say, "Every NFL player has a Y chromosome and only biological males have Y chromosomes", those statements would absolutely establish the conclusion that "All NFL players are male". But it isn't flawed if we end up concluding, "Thus, some NFL players might be male." The fact that a more powerful conclusion would also be true doesn't make the weaker conclusion an invalid one.

    4% picked this

  4. Something that is merely a

    Wrong Flaw: not Opinion vs. Fact

    This describes a semi-famous flaw Opinion vs. Fact. It would be appropriate if an author went from an opinionated premise to a factual conclusion, like, "Many people think that Ron Swanson moonlights as a locally famous saxophone player. Thus, apparently, Ron leaves work on some nights to go gig as a saxophonist." There, I treated a matter of opinion as though it were factual. There is a mix of fact and opinion in Dobson's argument, but our objection to his final move has nothing to do with treating an opinion as fact. Our objection is that even if the historians have shady grounds for their claim, that doesn't prove that their claim is untrue.

    19% picked this

  5. Dobson’s drawing the conclusion relies

    Wrong Flaw: not Equivocation

    This describes the famous Equivocation flaw, in which an author uses the same term or concept in two very different ways. This answer is almost always wrong, and we only pick it when we can find a term being used twice in the argument and define it two completely different ways. There's no such term in this argument that gets used twice, to mean two very different things.

    2% picked this

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