The Central Assumption of Causal Conclusions

Understanding this assumption is absolutely critical to your LSAT success. The
makers of the test will closely examine your knowledge of this idea, especially in
Strengthen and Weaken questions.
Understanding the assumption that is at the heart of a causal conclusion is
essential to knowing why certain answers will be correct or incorrect. Most
students assume that the LSAT makes basic assumptions that are similar to the
real world; this is untrue and is a dangerous mistake to make.
When we discuss causality in the real world, there is an inherent understanding
that a given cause is just one possible cause of the effect, and that there are other
causes that could also produce the same effect. This is reasonable because we
have the ability to observe a variety of cause and effect scenarios, and
experience shows us that different actions can have the same result. The makers
of the LSAT do not think this way. When an LSAT speaker concludes that one
occurrence caused another, that speaker also assumes that the stated cause is the
only possible cause of the effect and that consequently the stated cause will
always produce the effect. This assumption is incredibly extreme and farreaching,
and often leads to surprising answer choices that would appear
incorrect unless you understand this assumption. Consider the following
example:
Premise: Average temperatures are higher at the equator than in
any other area.
Premise: Individuals living at or near the equator tend to have
lower per-capita incomes than individuals living
elsewhere.
Conclusion: Therefore, higher average temperatures cause lower percapita
incomes.
This argument is a classic flawed causal argument wherein two premises with a
basic connection (living at the equator) are used as the basis of a conclusion that
states that the connection is such that one of the elements actually makes the
other occur. The conclusion is flawed because it is not necessary that the one
element caused the other to occur: the two could simply be correlated in some
way or the connection could be random.
In the real world, we would tend to look at an argument like the one above and
think that while the conclusion is possible, there are also other things that could
cause the lower per-capita income of individuals residing at or near the equator,
such as a lack of natural resources. This is not how speakers on the LSAT view
the relationship. When an LSAT speaker makes an argument like the one
above, he or she believes that the only cause is the one stated in the conclusion
and that there are no other causes that can create that particular effect. Why is
this the case? Because for an LSAT speaker to come to that conclusion, he or
she must have weighed and considered every possible alternative and then
rejected each one. Otherwise, why would the speaker draw the given
conclusion? In the final analysis, to say that higher average temperatures cause
lower per-capita incomes the speaker must also believe that nothing else could
be the cause of lower per-capita incomes.
Answer choices that otherwise appear irrelevant will suddenly be obviously correct
when you understand the central causal assumption.
Thus, in every argument with a causal conclusion that appears on the LSAT, the
speaker believes that the stated cause is in fact the only cause and all other
theoretically possible causes are not, in fact, actual causes. This is an incredibly
powerful assumption, and the results of this assumption are most evident in
Weaken, Strengthen, and Assumption questions. We will discuss this effect on
Strengthen and Assumption questions in a later chapter. Following is brief
analysis of the effect of this assumption on Weaken questions.

Recognizing Conclusions Without Indicators

Law Services says you are expected to possess, in their words, “a college-level
understanding of widely used concepts such as argument, premise, assumption, and
conclusion.”
Many of the arguments we have encountered up until this point have had
conclusion indicators to help you recognize the conclusion. And, many of the
arguments you will see on the LSAT will also have conclusion indicators. But
you will encounter arguments that do not contain conclusion indicators.
Following is an example:
The best way of eliminating traffic congestion will not be easily found.
There are so many competing possibilities that it will take millions of
dollars to study every option, and implementation of most options
carries an exorbitant price tag.
An argument such as the above can be difficult to analyze because no indicator
words are present. How then, would you go about determining if a conclusion
is present, and if so, how would you identify that conclusion? Fortunately,
there is a fairly simple trick that can be used to handle this situation, and any
situation where you are uncertain of the conclusion (even those with multiple
conclusions, as will be discussed next).
Aside from the questions you can use to identify premises and conclusions
(described earlier in this chapter), the easiest way to determine the conclusion
in an argument is to use the Conclusion Identification MethodTM:
Take the statements under consideration for the conclusion and place
them in an arrangement that forces one to be the conclusion and the
other(s) to be the premise(s). Use premise and conclusion indicators to
achieve this end. Once the pieces are arranged, determine if the
arrangement makes logical sense. If so, you have made the correct
identification. If not, reverse the arrangement and examine the
relationship again. Continue until you find an arrangement that is
logical.
Let us apply this method to the argument at the top of this page. For our first
arrangement we will make the first sentence the premise and the second
sentence the conclusion, and supply indicators (in italics):
Because the best way of eliminating traffic congestion will not be
easily found, we can conclude that there are so many competing
possibilities that it will take millions of dollars to study every option,
and implementation of most options carries an exorbitant price tag.
Does that sound right? No. Let us try again, this time making the first sentence
the conclusion and the second sentence the premise:
Because there are so many competing possibilities that it will take
millions of dollars to study every option, and implementation of most
options carries an exorbitant price tag, we can conclude that the best
way of eliminating traffic congestion will not be easily found.
Clearly, the second arrangement is far superior because it makes sense. In
most cases when you have the conclusion and premise backward, the
arrangement will be confusing. The correct arrangement always sounds more
logical.