The passage provides the strongest support for inferring that Lessing holds which one of the following views?

First on August 15 at 10:15PM

Lost and frustrated

Can someone from the LSAT Max team please write out and define each of the possible Errors of Reasoning we will be asked to identify? How are we supposed to know the error is called "fallacy of composition", and what exactly the difference is between that fallacy and the "fallacy of division"...is there a lesson plan you give that explains the specific flaws that are typical in an LR argument? Or are we just expected to know those terms? You mention the names of the flaws as though they are obvious. How, for example, are we to simply assume that the bank's security guard is "biased"? Please provide a clearer lesson plan on these types of questions...walking through the answers one by one doesn't really help when we have no idea where you are pulling these "identifiable-by-name" flaws from...

2 Replies

Ravi on August 15 at 11:11PM

@ShannonOh22,

There are all sorts of flaws that can appear on the LSAT. Knowing that
there exists a flaw in an argument and being able to point out what
the flaw is in general terms is far more important than knowing
technical lingo for calling specific flaws certain names. As noted in
another response, for your question regarding curriculum, I recommend
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Regarding types of flaws on the LSAT, here are some of the most common
ones you'll encounter:

1) Confusing necessary for sufficient conditions and vice versa

2) Circular reasoning (assuming what the argument is attempting to prove)

3) Confusing Correlation for Causation

4) Equivocating terms (using a term in an argument with more than one
meaning inconsistently)

5) false analogy

6) false dichotomy (pretending to divide things into to binary halves
when there isn't an actual contradiction, such as saying that there
are basketball players and soccer players). A real contradiction would
be saying there are basketball players and non-basketball players.
Everything in the world can be put into one of those two categories.

7) Sampling fallacy (taking results from a sample or survey and making
a sweeping claim from that)

8) Confusing one potential solution for being the only potential solution

9) Showing that an argument fails and then concluding that the
opposite of that argument's conclusion is true

Let us know if this helps and you'd like more clarification.

Irina on August 16 at 12:35AM

@Shannon,

Thank you for your question. While instructors do not have any control over the course content, I can offer some suggestions on approaching flaw questions based on my experience. First, it is by no means necessary to use specific names for a particular error in reasoning, it is more likely that on a real test you would be simply asking yourself "why is this argument flawed? " and answering it in plain English rather than thinking "this looks like a fallacy of division." The best way to learn to identify flawed arguments is practice, the more flawed questions you do and try to figure out yourself why it is flawed before looking at the video explanation, the more intuitive it becomes. There are great books on logical flaws - the one I used for a logic course was "Attacking Faulty Reasoning" by Edward Damer - that go into great detail on breaking down the fallacies, but there is no list of all possible fallacies that could be used by the LSAT writers.

This is merely a list of common ones off the top of my head:

(1) Deductive inference errors - common in flawed parallel reasoning questions:

(a) Affirming the consequent
This fallacy takes the following form. Let's take a conditional statement:

If P (also known as the antecedent) then Q (also known as the consequent)
Q
Therefore, P

If it is Saturday then it is weekend
It is weekend
Therefore, it is Saturday.

The valid argument form is:
If P then Q
P
Therefore, Q

(b) Denying the antecedent

If P then Q
Not P
Therefore, not Q

If it is Saturday then it is weekend
It is not Saturday
Therefore, it is not the weekend

The valid argument form is:

If P then Q
Not Q
Therefore, not P

(2) Fallacies of relevance
This is a larger group of fallacies that represent situations when the conclusion relies on evidence or a fact that is irrelevant to the argument. They usually take a form of an appeal to tradition/ common opinion/ irrelevant authority.

(3) Cause and effect
This fallacy occurs when the argument presumes that one event causes another event solely because they are correlated, whereas correlation alone is never a sufficient condition to establish causation. Example:

As the sales of ice cream go up so do the sales of sunglasses.
Ice cream causes people to buy sunglasses.
False! There is a third variable - summer season - that causes both.

(4) Circular reasoning, also known as begging the question - popular answer choice but incorrect 99% of the time
LSAT likes to use it as one of the answer choices in a form of "the argument takes for granted what it sets out to prove" or "assumes what it seeks to establish" but it is extremely rare for it to be the correct answer choice. The reason why is because circular reasoning is easy to spot and happens when the conclusion simply restates one or more of the premises.

X is true because of Y
Y is true because of X

For example:

Driving and texting should be illegal because it is against the law.

(5) Unrepresentative sample
This fallacy uses a sample of the population/ limited experimental data to draw a general conclusion. Example:

The survey of homeowners revealed that 99% of them have a household income of over $150,000. Therefore, the U.S. economy is doing great.

(6) Fallacy of division/ composition

Fairly common on the LSAT though I have never seen the question actually use the term "fallacy of division" or "fallacy of composition." The fallacy of division happens when one erroneously attributes a characteristic of the whole to each of the objects within it, it assumes that because x is true as a whole, it is true of the parts.

For instance:

Housing prices are down in the U.S.
Housing prices are thus down in my neighborhood.

The fallacy of composition assumes that because x is true of the parts, it is true of the whole as well. The correct answer choice commonly appears on the LSAT as "assuming that because something is true of each of the parts of a whole it is true of the whole itself" or “improperly infers that each and every member has a certain characteristic from the premise that many members have that characteristic"

For instance:

Everyone in my office has received a raise this year.
The average U.S. wages must have gone up this year.

This is by no means an exhaustive list but more intended as a helpful starting point as you go through the flaw questions.