Logical Reasoning

PT102 · S3 · Q7 A commonly accepted myth is that

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A commonly accepted myth is that left-handed people are more prone to cause accidents than are right-handed people.

Conclusion

It's a myth that lefties are more prone to cause accidents than are righties. (i.e. Lefties are not more prone to cause accidents than are righties)

Evidence

More household accidents are caused by righties than lefties.

Evaluate

If we're really on top of our game, we might notice the switch from Absolute (Number) to Relative (Likelihood)

Given that ... more household accidents are caused by righties than lefties, How could we still say that ... lefties are more prone to cause accidents?

One objection could be that the evidence only speaks to household accidents, whereas the conclusion deals with any type of accident.

Another objection could be to say that there are way more right handed people than left handed people in the world (like an 8:1 ratio), so of course the raw total will be higher for right handed people.

But that's not how you measure "prone" to something. That needs to be a per capita type stat, as in we need to express it as a percent of the population.

If 13% of lefties have caused an accident whereas only 6% of righties have, then left handed people are more prone to accidents (even though most accidents will be caused by right handed people, since we're taking 6% of a number that's 8 times bigger than the number we're taking 13% of).

When we lament that in America black people are more prone to by incarcerated for petty drug charges, it doesn't undermine that claim for someone to say,

We need to measure it as a percent of the underlying population. If blacks make up 17% of the population but account for 30% of the drug arrests, whereas whites make up 45% of the population but account for 35% of the drug arrests, that would show that black people are more likely to be incarcerated for drugs.

Goal

Look for an answer complaining about the switch from household accidents to all accidents, complaining about the switch from evidence about raw numbers to a conclusion about propensity, or objecting that maybe it's unfair to compare the raw number given that there are like 8 times as many right handed people.

7.

The reasoning is flawed because the argument

  1. makes a distinction where there

    Opposite, if anything

    We weren't complaining that the author made a distinction. We accept that right handedness is distinct from left handedness. We were actually complaining that the author made an equivalence when there is a real distinction between the things. She equated "accidents" with "household accidents". She equated "higher total number" with "higher propensity".

    4% picked this

  2. Correct

    takes no account of the

    Why this is right

    This speaks to the objection of, "Naturally, there are more accidents caused by right handed people; there are like 8 times as many right handed people in the world as left handed people." It also speaks to the objection of even citing raw numbers in the evidence when the conclusion is about how prone / how likely a certain group is, so we would never measure that in raw numbers. We would always measure it in relation to the relative size of the underlying population.

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

    72% picked this

  3. uses the word “accidents” in

    Wrong Flaw

    This answer refers to the famous flaw Equivocation, in which the author uses the same term or concept in two very different ways. For example, if we had used accident at one point to describe a kid peeing their pants and later we were using accident to mean a car wreck. This argument uses accident consistently; it just concludes something about all accidents while only providing evidence about a subset, household accidents.

    11% picked this

  4. ignores the possibility that some

    Not an Objection

    Does it weaken the argument if we say, "at least one household accident is caused by more than one person"? No, that's such a puny one-data-point type of objection.

    3% picked this

  5. gives wholly irrelevant evidence and

    Too Strong: wholly irrelevant

    The evidence is not wholly irrelevant. It's certainly incomplete, but it could be relevant. Household accidents are part of "accidents", so it's part of the story we're analyzing in the conclusion.

    10% picked this

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