Logical Reasoning

PT101 · S3 · Q10 All material bodies are divisible

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All material bodies are divisible into parts, and everything divisible is imperfect.

Conclusion

The spirit is not a material body.

Intermediate Conclusion

All material bodies are imperfect.

Evidence

All material bodies are divisible, and everything divisible is imperfect.

Evaluate

The argument contains two explicit premises, each telegraphed by "it follows".

The first sentence contains two claims, both of which are conditional ("all" and "everything" are both sufficient indicators): material body → divisible divisible → imperfect

Since those chain together, we know that "material bodies are imperfect", which is what the 2nd sentence, the Intermediate Conclusion, gives us.

So the Intermediate Conclusion is already drawing a logically airtight inference from the two claims in the first sentence.

The gap must be in the move from Intermediate Conclusion to Main Conclusion.

Intermediate Conc: material body → imperfect

Main Conc: spirit → ~material body

We should contrapose either the IC or the MC so that they have the same trigger or same outcome. Let's contrapose the MC. We'll also extend the conditional line so that we can better visualize the missing piece we need to form the logical conveyor belt that the Conclusion is trying to build.

Intermediate Conc: material body → imperfect

Main Conc: material body --------------------------> ~spirit

If I know X → Y and I'm trying to prove X -----------> Z then I'm missing Y -----> Z

If we know material body → imperfect and we want to prove material body --------------------------> ~spirit then we're missing imperfect ------------> ~spirit

Goal

We need to hear "if it's imperfect, it's not spirit", or the contrapositive, "if it's spirt, it's perfect"

Since the concept of "spirit" is found in the conclusion and nowhere else, it must be in the correct answer. Get rid of anything that doesn't talk about "spirit".

10.

The final conclusion above follows logically if which one of the following is assumed?

  1. Everything divisible is a material

    Unrelated to Goal

    This says nothing about "spirit" so it can't possibly allow us to prove a claim about "spirit" (we currently have no premises about "spirit", so this answer must provide us with one).

    5% picked this

  2. Nothing imperfect is indivisible.

    Unrelated to Goal

    This says nothing about "spirit" so it can't possibly allow us to prove a claim about "spirit" (we currently have no premises about "spirit", so this answer must provide us with one).

    7% picked this

  3. The spirit is divisible.

    Doesn't Help

    This gives us spirit ? divisible and we're trying to add it onto premises in order to derive spirit ? ~material body We have a rule that says divisible ? imperfect So we can combine this answer choice with the 2nd claim from the argument and derive that: spirit ? divisible ? imperfect But is there a way to get from "imperfect" to "not material body"? No. We have a connection that says material body ? imperfect But we would need one that says imperfect ? ~material body

    3% picked this

  4. Correct

    The spirit is perfect.

    Why this is right

    This is what we predicted. We have this relationship in our Evidence: material body ? imperfect perfect ? not material body So if we add on this answer choice spirit ? perfect to that premise perfect ? not material body then we've derived the conclusion: spirit --------------> not material body

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

    68% picked this

  5. The spirit is either indivisible

    Unclear Impact

    Sometimes correct answers do function off an either/or choice. You just have to prove that in either case, you get to the conclusion. If spirit is indivisible, then we know that it's not a material body (from the very first claim in the argument). So in that world, we will have proven the conclusion. But what about the world in which the spirit is imperfect? If spirit is imperfect, we can't say anything about whether or not it's a material body. In fact, since we know that all material bodies are imperfect, it seems possible that the spirit is a material body. This answer is confusing because in one of its two possible worlds, we definitely DO prove the conclusion. But we don't know for sure that we live in that world, so we haven't definitively proven the conclusion. Say that I'm trying to prove that Gus loves Taylor Swift. We have rule that says: if you're at T-Swift's show, you love her. If I tell you that Gus is at T-Swift's show or he's at the bowling alley, have I convinced you that Gus loves Taylor Swift? Of course not. That's what this answer is doing.

    16% picked this

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