Logical Reasoning

PT104 · S4 · Q10 Unplugging a peripheral component

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Unplugging a peripheral component such as a “mouse” from a personal computer renders all of the software programs that require that component unusable on that computer.

Conclusion (So)

The mouse for Fred's computer must have become unplugged.

Evidence

Unplugging a peripheral such as a mouse makes every program that requires it unusable on that computer.

A program on Fred's computer is unusable, and it requires a mouse.

Evaluate

The first sentence is both Causal and Conditional, causal because of the verb "renders" and conditional because of its certainty.

It's not obvious it's a conditional, which is a shame, because whenever we're doing Flaw and see a conditional premise, it makes get on guard for an Illegal Reversal / Negation (i.e. the Nec vs. Suff Flaw).

If we looked at the first sentence as a rule, it would be saying Unplugged mouse → Software unusable

The second sentence tells us that the right side of the rule is happening. A program on Fred's machine is unusable. The author then runs the rule backward and concludes the mouse must be unplugged.

That illegal reversal is the Famous Flaw of Necessary vs. Sufficient. Unplugging the mouse is one way to make the program unusable, but nothing says it is the only way.

If we didn't pick up on this illegal reversal, we would assign ourselves the role of arguing that "Fred's mouse isn't unplugged", and then the author would say "then how come his software isn't working?"

We'd have to respond with some alternate explanation: the program is corrupted, the mouse is plugged in but broken, the software license is expired, etc.

Goal

Look for an answer calling out the Nec / Suff flaw, or one that raises one of these other possibilities (maybe the software is unusable for some other reason).

10.

The argument is most vulnerable to which one of the following criticisms?

  1. It contains a shift in

    Equivocation

    "Unusable" means the same thing in both places it appears: the program does not work on that computer. Nothing in the argument turns on whether the program is down for good or only for the moment.

    1% picked this

  2. Correct

    It treats an event that

    Why this is right

    If we're scanning for Nec vs. Suff language, then we like "certain" as a synonym for Sufficient and of course "necessary" as a match for Necessary. If not, we see the structure, treats X as though it's Y which means we should see whether X matches something said in the evidence and whether Y matches the conclusion or an idea the author had en route to it. Did the evidence talk about "an event that can cause a certain result"? Yes, unplugging the mouse is an event that can cause a program to become unusable. Does the author then start thinking that "an unplugged mouse is required for a program to be unusable"? Yes, the author then reasons that because the program is unusable, the mouse must have been unplugged. That only follows if unplugging is the one and only way for the program to fail, which is to say, if unplugging is necessary for the result.

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

    93% picked this

  3. It introduces information unrelated to

    Bad Description

    The evidence is a rule connecting an unplugged mouse to an inoperational program and a fact about Fred's inoperational program. Those are both relevant to the conclusion about Fred's supposedly unplugged mouse.

    1% picked this

  4. It attempts to support its

    Bad Description

    The generalization in the first sentence is not too broad. I'm not sure how we would ever judge a premise as too broad. We judge conclusions that way when they are broader than what the evidence permits us to conclude, but we never hate on premises for being too broad. You're kind of allowed to present whatever evidence you want. The only rules of this reasoning game we're playing are about whether you're drawing a conclusion that is justified by the evidence presented.

    2% picked this

  5. It overlooks the possibility that

    Bad Objection

    Since this starts with fails to consider / overlooks the possibility, we can ask ourselves whether it would weaken if we said, "Hey, author, some programs don't need a mouse!" It would not, because the evidence told us that the inoperational software program on Fred's computer does require a mouse. So this objection would be irrelevant to the conversation at hand.

    3% picked this

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