Flaw/ Descriptive Weakening Flashcards
Similar to…
- weakening questions
- method reasoning
- describe
why is wrong but….
how does it need to look it to make it wright
For each answer choice ask:
- descriptively accurate? (yes, the argument does assume this)
- describe the flaw? (is that why the argument is wrong)
in order for answer choice to be correct must past step 1 and 2
19 different kinds of flaws.
However, it does not contain all kinds of flaws.
- Attacking the source of the argument
To attack an argument you may attack:
1) the premises (which never happens on the LSAT); or
2) the support the premises give to the conclusion
What you DO NOT get to do is to attack the author, his past acts or arguments, his motivation, where the argument comes from, or anything other than (1) or (2).
Sometimes you’ll hear this type of flaw described as an “ad hominem,” which is Latin for “to the man.” For instance, saying that the Congressman voted to change the law because he had significant investments in the pertinent industry, and therefore the bill should not be passed. That argument attacks the person making the argument but says nothing about whether there are justifiable reasons the bill should or should not be passed.
- Uses terms unclearly/equivocation
The author uses a term (with more than one meaning) inconsistently. For example, “public interest” in one sense means what is in the best interest of the public (e.g., clean air, roads, schools). In another sense, it means what the public is interested in (e.g., celebrity gossip). The shift in word meaning will often be subtle and hard to notice.
- Analogies that really aren’t analogous enough
All arguments by analogy fall apart at some point. At some point the two things being analogized lose their relevant similarities and the analogy cannot continue. We can say attacking LSAT questions is like attacking enemy starships.
But it’s not is it.
- Appealing to authority in an area outside their expertise
Appealing to an authority where the subject matter is outside the expertise of the authority. For example, a dentist’s opinions on automotive maintenance is not authoritative.
- Causation confusions
Whenever the LSAT concludes or assumes that A causes B, 99.9% of the time it’s wrong. They’ll tell you A is correlated with B or that A coincided with B and therefore A caused B. Maybe. That’s just one possible explanation for the correlation. Here are the other 3 possible explanations:
1) B caused A
2) C caused both A and B
3) A and B are merely coincidentally correlated and really something else, X, caused B. We see this a lot with accident rate and speed sign questions. New speed limit sign was put up! Accident rates drop! Therefore, it must be that the new speed limit sign dropped the accident rate. Maybe. But maybe there was an increase in cop cars patrolling the area and that’s what actually caused the drop in accident rates. The speed limit sign was just coincidentally there.
- Circular reasoning
Assuming what you’re trying to prove. The premise is a mere restatement of the conclusion.
“Everything I say is true. This is true because I said it, and everything I say is true.”
- Confusing necessary and sufficient conditions
The oldest trick in the book.
- False dichotomy
A false dichotomy only pretends to divide the universe into two binary halves. It is not a real contradiction. Consider this real contradiction: cats and non-cats. That cleanly cuts the universe into two halves. Garfield? Simba? Hello Kitty? That furry creature that lives in your home, eats your food, drinks your water, basically is dependent on you for its very survival but considers you with utter disdain? Yeah, cats.
What about Albert Einstein, the MacBook Pro, dogs, ice cream, love? Those are non-cat.
Everything you can conceive of falls cleanly into either the “cats” category or the “non-cats” category and nothing is left out.
Here’s a false dichotomy: Cats and dogs. See how that leaves out Einstein, MacBook Pro, and Love? They are neither cats nor dogs.
Basically, the LSAT writers know we often can’t tell the difference between false dichotomies and true contradictions and they hurt us.
- Confusing probability for certainty
Could be is not must be. Even if something is 99% likely to happen, it does not mean that it will happen.
- Confusing “is” for “ought”
Don’t confuse the descriptive for the prescriptive. Descriptive simply describes the state of the world. The tree is small. The lake is murky. Prescriptive reveals values. The tree ought to be big. The lake should be clear. The prescriptive reveals what we care about. You will typically encounter a descriptive premise leading to a prescriptive conclusion. For example, the house is on fire therefore we should put the fire out. That’s not a good argument. There may be a number of reasons why we wouldn’t want to put the fire out. We always need a bridge premise to take us from the descriptive world of the premises to the prescriptive world of the conclusion. The bridge premise in the example argument above would be: Houses that are on fire ought to have their fires put out.
- Percentages v. quantity
Percentages don’t necessarily reveal quantity and vice versa.
For example, Group A wants a 10% raise and Group B wants a 50% raise. Who will earn more money afterward? Who is asking for more money? We have no way to know based on this information.
