Complex Arguments

A simple argument does not mean that the argument is easy to understand!
Simple in this context means that the argument contains only a single conclusion.
Up until this point, we have only discussed simple arguments. Simple
arguments contain a single conclusion. While many of the arguments that
appear on the LSAT are simple arguments, there are also a fair number of
complex arguments. Complex arguments contain more than one conclusion. In
these instances, one of the conclusions is the main conclusion, and the other
conclusions are subsidiary conclusions (also known as sub-conclusions).
While complex argumentation may sound daunting at first, you make and
encounter complex argumentation every day in your life. In basic terms, a
complex argument makes an initial conclusion based on a premise. The author
then uses that conclusion as the foundation (or premise) for another
conclusion, thus building a chain with several levels. Let us take a look at the
two types of arguments in diagram form:
In abstract terms, a simple argument appears as follows:
Conclusion =====> Premise
As discussed previously, the premise supports the conclusion, hence
the arrow from the premise to the conclusion. By comparison, a
complex argument takes an initial conclusion and then uses it as a
premise for another conclusion:
Conclusion=======> Conclusion/Premise======> Premise
Thus, a statement can be both a conclusion for one argument and a premise for
another. In this sense, a complex argument can appear somewhat like a ladder,
where each level or “rung” is used to build the next level. Given enough time
you could build an argument with hundreds of levels. On the LSAT, however,
there are typically three or four levels at most. Let us look at an example of a
complex argument:
Because the Vikings have the best wide receiver in football, they
therefore have the best offense in football. Because they have the best
offense in football, they will win the Super Bowl next year.
In this argument, the first sentence contains a premise followed by a
conclusion. This initial conclusion is then used in the second sentence as a
premise to make a larger conclusion:
Premise: “Because the Vikings have the best wide receiver in football,”
Sub-Conclusion (conclusion of the previous premise/Premise for the
following conclusion): “they therefore have the best offense in
football.”

Main Conclusion: “they will win the Super Bowl next year.”
As we will see in Chapter Twelve while discussing Method of Reasoning
questions, one of the most commonly used complex argument forms is to
place the main conclusion in the first sentence of the argument, and then to
place the sub-conclusion in the last sentence of the argument, preceded by a
conclusion indicator. This form is quite useful since it tends to trick students
into thinking the last sentence is the main conclusion.
Another form of complex argumentation occurs with two-speaker stimuli. In
these questions, two separate speakers are identified, and each presents his or
her own argument or comment. Here is an example from the June 2003 LSAT:

Anne: Halley’s Comet, now in a part of its orbit
relatively far from the Sun, recently flared brightly
enough to be seen by telescope. No comet has ever
been observed to flare so far from the Sun before,
so such a flare must be highly unusual. 
Sue: Nonsense. Usually no one bothers to try to
observe comets when they are so far from the Sun.
This flare was observed only because an
observatory was tracking Halley’s Comet very
carefully.
 
In the argument above, each speaker presents premises and a conclusion. As
often occurs with this form of question, the two speakers disagree.
One of the benefits of a two-speaker stimulus is that the test makers can
introduce multiple viewpoints on the same subject. As you might imagine, the
presence of multiple viewpoints tends to be confusing, and the extra
viewpoints offer the test makers the opportunity to ask a wider variety of
questions.