LSAT common Flaws Flashcards
Sampling Flaw
Argument extends limited info and tries to apply it more widely than is reasonably justifiable.
I.E. The arguer draws a general conclusion based on what’s true able an inappropriate or biased sample.
How to detect a sampling flaw? Example?
Look for:
- Polls, surveys or studies
- Data or studies that comes from limited sources (“one meteorologist”)
- A shift from specific evidence to a general conclusion
(EX: evidence about 3 doctors and the conclusion is about all doctors) - A shift from evidence to conclusion during which the arguer assumes- but doesn’t demonstrate- that one is acceptably representative of the other
EX: Everyone I know want to quit their job, so this country is headed for an employment crisis.
Ad Hominem
An arguer criticize’s someones actions, character or motives as a reason to not heed their argument
i. e. the arguer attacks another arguer instead of the argument itself.
* It’s important to remember that the identity or motives of an arguer don’t affect the validity of that person’s argument. Corrupt, unintelligent, biased people can make valid arguments. Moreover, if someone’s a hypocrite (they act in a different way than what they advise), it doesn’t mean they’re wrong.
Example: My doctor tells me it’s bad for your lungs to smoke cigarettes, but I know he’s lying. I saw him furtively smoking a cigarette the other day.
Faulty analogy
Scope shift, in that the arguer compares two things or situations, but the two things or situations being compared, aren’t sufficiently alike
Causation/ Correlation
The arguer takes tow things that happen at the same time (correlation) and concludes that one of those caused the other (causation). The arguer overlooks two important possibilities
1) a third, unaccounted-for thing could actually be the cause
2) the cause-and-effect could actually be in reverse order of what the arguer believes
EX: Last summer, ice cream sales decreased while homocide rates more than doubled in this region. We should look into selling more ice cream in order to keep people safe.
Quantity VS. Percent
The arguer test quantities and parents of something as if they’re interchangeable, but %’s themselves don’t tell you anything about the actual numbers.
EX: if 10% of the people with disease X died last year, whereas 50% of the people with disease Y died last year, Clearly, disease Y is hurting our population more than Disease X is.
BUT, what is 1,000,000 people had disease X and only 4 people had disease Y
Lack of evidence as proof
The arguer takes a lack of evidence for a conclusion as if that conclusion is definitely wrong.
Also known as taking an absence of evidence for “evidence of absence”
EX: Alien life has never been discovered, so it is clear that alien life doesn’t exist.
False Dichotomy
The arguer acts as if there are only two choices, when in fact it isn’t an either/or situation
EX: If you’re not with us, then you against us.
The arguer looks over the possibility that someone could remain neutral.
Possibility vs. Certain
The speaker assumes that because something is possible, then it’ll happen
EX:
Last year we didn’t have enough budget money for employees raises, but this year there’s plenty of money in the budget. So, it is clear that the company will give out raises this year.
Circular Reasoning
“Begging the Question”
The arguer assumes that his or her conclusion is already true when attempting to prove that same conclusion.
EX: Duplicity is an unattractive characteristic since it is repulsive to lie and deceive
Equivocation
The argues uses a potentially ambiguous term in more that one sense and consequently misleads the reader
EX: A feather is light, and what’s light can’t be dark, so a feather can’t be dark.
Syllogistic Fallacy: Undistributed Middle
This is a fallacy involving three sets: A, B and C. It is the assumption that because all A are members of C, and all B are members of C, that all A are B.
Weaknessess
There is usually no reason to believe that two members of a group are identical or related, nor two subgroups of a group.
Other example
A. Fred is an atheist who lives in California.
B. Ted is also an atheist living in California.
C. Therefore Fed and Ted are actually the same person.
Other example
A. All cherry tomatoes are red things.
B. All cherries are red things.
C. Therefore all cherry tomatoes are cherries.
Sweeping Generalization
An argument is constructed in which a simplistic general rule is assumed to be more widely true, therefore an exception is ignored.
Example
Some cats are orange. Therefore all cats are orange.
Appeal to Majority
Proposition A is believed by the majority of people.
Therefore it is true.
Affirming a Disjunct
This is also known as False exclusionary disjunct.
Two propositions are given and they are independent. When one of them turns out to be true, the arguer claims the other is false.
EX: The baby has red hair, or the baby has web feet. The baby does not have web feet therefore it has red hair.
In this fallacy the arguer is making a mistake of assuming that two propositions are connected when they are not. You should point this out and emphasize that these two things are independent.
The arguer is assuming that an “or” relationship is exclusive rather than inclusive.
