The Language of Argument

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su p p r e s s e d P r e m i s e s

On the other hand, suppressed premises can also be used improperly.

People sometimes suppress questionable assumptions so that their oppo-

nents will not notice where an argument goes astray. For example, when

election debates turn to the topic of crime, we often hear arguments like this:

My opponent is opposed to the death penalty, so he must be soft on crime.

The response sometimes sounds like this:

Since my opponent continues to support the death penalty, he must not

have read the most recent studies, which show that the death penalty

does not deter crime.

The first argument assumes that anyone who is opposed to the death pen-

alty is soft on crime, and the second argument assumes that anyone who

read the studies in question would be convinced by them and would turn

against the death penalty. Both of these assumptions are questionable, and

the questions they raise are central to the debate. If we want to understand

these issues and address them directly, we have to bring out these sup-

pressed premises openly.

The following arguments depend for their validity on suppressed premises of

various kinds. For each of them, list enough suppressed premises to make the

argument valid and also to show why it is valid. This might require several

suppressed premises of various kinds.

example: Carol has no sisters, because all her siblings are brothers.

suppressed Premises: A sister would be a sibling.

A brother is not a sister.

1. Britney Spears is under age thirty-five. Therefore, she cannot run for
   president of the United States.


2. Nixon couldn’t have been president in 1950 because he was still in the
   Senate.


3. 81 is not a prime number, because 81 is divisible by 3.


4. There’s no patient named Rupert here; we have only female patients.


5. Columbus did not discover the New World because the Vikings explored
   Newfoundland centuries earlier.


6. There must not be any survivors, since they would have been found by
   now.


7. Lincoln could not have met Washington, because Washington was dead
   before Lincoln was born.


8. Philadelphia cannot play Los Angeles in the World Series, since they are
   both in the National League.

exercise iX

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