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Part of the Whole/Whole of the Part 
These types of flaws occur when the author assumes that because something is true of the part it is also true of the
whole. Conversely, the author may also erroneously assume that whatever is true of the whole is true of the part. For
example, if the author asserts that he read a page in a book and it was good and then concludes that the book must
be good, his reasoning is flawed. He has assumed that because a part of something was good (a page), then the entire
thing must be good (the book). Similarly, if the author asserted that because the book was good, then every page in the
book must be good, his reasoning is also flawed. You cannot attribute the characteristics of part of something to the
whole or characteristics of the whole of something to each of its individual parts without proper evidence to establish
the veracity of your claim. 
Errors in Conditional Reasoning 
Conditional reasoning is the logical relationship characterized by “if-
then” statements where “if” is the sufficient and “then” 
is the necessary. Conditional reasoning is also commonly symbolized as A

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B, which is written as “If A, then B.” Errors 
in conditional reasoning occur when the author fails to properly understand the sufficient/necessary relationship and
makes inappropriate conclusions based on an erroneous understanding. Conditional reasoning has many complex nuances;
many of these will not occur on the exam. But you will need to understand the basics. If you encounter a conditional
relationship in the argument prompt, you should always examine it closely to ensure that it conforms to the conditional
reasoning conventions. If it does not, then the argument is flawed and you will need to explain why. Let us look at a
conditional reasoning statement and examine both the logical and illogical conclusions that can subsequently be made. 
If it rains tomorrow, then the store will be closed.
The sufficient is “If it rains” while the necessary is “the store will be closed.”
The only correct conclusions that you can draw from this statement are:
• If it rains, the store will be closed. Whenever the sufficient happens, the necessary 
asserts that it rained but also asserts that the store is open, the argument is flawed since the necessary
occur whenever the sufficient occurs. 
• If it does not rain, the store can be open or closed. The necessary can occur without the sufficient. If the author
concludes that since the store is closed, it must have rained, the argument is flawed since it fails to consider that
the necessary can occur without the sufficient.