Large inequalities in wealth always threaten the viability of true democracy, since wealth is the basis of political ...

Ravi March 19, 2020

@Shirnel,

Happy to help.

Let's take a look at this argument.

If we digram this argument, we have "wealth inequality-->threatens
democracy" as the conclusion.

The support for this conclusion is "wealth-->political power and true
democracy-->equal distribution of power"

At first glance, it doesn't appear that these statements link up to
get us the conclusion, but if we take the contrapositive of the second
premise and put things back together, we get "wealth-->political power
for wealthy individuals (unequal distribution of power)-->not true
democracy (threatens democracy). Because this is a parallel question,
we're looking for an answer choice that mimics this basic structure.

Also, note that there aren't any quantifiers or compound statements in
this stimulus, so any answer choice that has a quantifier and/or a
compound statement can be eliminated.

(A) says, "Consumer culture and an emphasis on technological
innovation are a dangerous combination, since together they are
uncontrollable and lead to irrational excess."

The fact that (A) has a compound statement (using the word "and")
means we can get rid of this choice right away.

(B) says, "If Sara went to the bookstore every time her pocket was
full, Sara would never have enough money to cover her living expenses,
since books are her love and they are getting very expensive."

The problem with (B) is that it's an invalid argument. We don't have
any idea what Sara's living expenses are, how many money she has, or
whether she actually purchases the books, so this argument doesn't
work. Thus, it's out.

(C) says, "It is very difficult to write a successful science fiction
novel that is set in the past, since historical fiction depends on
historical accuracy, whereas science fiction does not."

Like (B), (C) is also an invalid argument. Historical fiction depends
on historical accuracy, but this doesn't matter since the goal is to
write science fiction. Thus, (C) is out.

(D) says, "Honesty is important in maintaining friendships. But
sometimes honesty can lead to arguments, so it is difficult to predict
the effect a particular honest act will have on a friendship."

(D) doesn't really have a conclusion. Additionally, there's a
quantifier in this answer choice ("some"), so we can get rid of it.

(E) says, "Repeated encroachments on one's leisure time by a demanding
job interfere with the requirements of good health. The reason is that
good health depends on regular moderate exercise, but adequate leisure
time is essential to regular exercise."

(E) is a valid argument, and it parallels the diagram we made for the
stimulus nicely.

Good health-->regular moderate exercise-->adequate leisure time

Conclusion: encroachments on leisure time by demanding job-->
interfere with good health

Like the stimulus, we have a transitive structure with three terms
connected together. Also, like the stimulus, there is some work
required for using the contrapositive to get thinks linked together
well, so (E) parallels the stimulus well and is the correct answer
choice.

Does this make sense? Let us know if you have any questions!

Ravi March 19, 2020

I'll also note that getting comfortable with S&N conditions takes time, and you will eventually become very comfortable with these. A good thing to keep in mind is to always think about doing contrapositives to help see how the chains could come together. You want identical terms to appear on the sufficient side of the arrow in one premise and the necessary in the other to make larger chains.

Ileri November 14, 2021

Actually the first premise is political power ---> wealth, according to the question and video explanation. I'm confused now that you diagram it as Wealth ----> political power.

Can you please confirm which it is? thanks

Ryn November 18, 2021

Me too, please.

Ravi February 8, 2022

@ileri and @Ryn, apologies, there was a typo there.

The final premise of this argument is the easiest to diagram, so starting there, we get

True democracy—>equal power distribution (not equal power distribution—>not true democracy)

In the premise before this one, the. Author says that wealth is the basis of political power, which means it’s a necessary condition

Power-->wealth (not wealth—>not political power)

From both of these statements, the author concludes that inequalities in wealth always threaten the viability of true democracy.

Large wealth inequalities—>threaten true democracy

If you look at the terms in the conclusion, large wealth inequalities more or less means not wealth, which is the negation of the necessary condition of our second premise. Threaten true democracy more or less means not true democracy, which is the negation of the sufficient condition of the first premise we diagrammed.

Thus, the basic structure of this argument is

A—>B

B—>C

Combining the two premises, we get

A—>B—>C (not C—>not B—>not A)

Then in the conclusion, we’re told we have not C, therefore not A, so it’s using the contrapositive of our diagram.

E is a perfect match, as it’s a valid argument that has three terms being linked up into a transitive chain, and it’s also using the contrapositive of the chain to arrive at its conclusion.


Premise 1: Good health—>regular moderate exercise (A—>B)

Premise 2: Regular exercise—>adequate leisure time (B—>C)

Conclusion: Repeated encroachments—>interfere with requirements of good health (Not C—>Not A)

Ravi February 9, 2022

There was a typo in my original response, so apologies for that.

The final premise of this argument is the easiest to diagram, so starting there, we get

True democracy—>equal power distribution (not equal power distribution—>not true democracy)

In the premise before this one, the. Author says that wealth is the basis of political power, which means it’s a necessary condition

Power-->wealth (not wealth—>not political power)

From both of these statements, the author concludes that inequalities in wealth always threaten the viability of true democracy.

Large wealth inequalities—>threaten true democracy

If you look at the terms in the conclusion, large wealth inequalities more or less means not wealth, which is the negation of the necessary condition of our second premise. Threaten true democracy more or less means not true democracy, which is the negation of the sufficient condition of the first premise we diagrammed.

Thus, the basic structure of this argument is

A—>B

B—>C

Combining the two premises, we get

A—>B—>C (not C—>not B—>not A)

Then in the conclusion, we’re told we have not C, therefore not A, so it’s using the contrapositive of our diagram.

E is a perfect match, as it’s a valid argument that has three terms being linked up into a transitive chain, and it’s also using the contrapositive of the chain to arrive at its conclusion.


Premise 1: Good health—>regular moderate exercise (A—>B)

Premise 2: Regular exercise—>adequate leisure time (B—>C)

Conclusion: Repeated encroachments—>interfere with requirements of good health (Not C—>Not A)