Arguments: the basics
An argument in logic is not a quarrel or dispute; instead, it is a list of sentences. The last
sentence is the conclusion, and the other sentences are the premises. Thus:
No professors are ignorant.
All ignorant people are vain.
No professors are vain.
All lions are fierce.
Some lions do not drink coffee.
Some creatures that drink coffee are not fierce.
are both arguments. (These two examples are taken from Lewis Carroll, who was an
amateur logician, as well as the author of
Alice in Wonderland
.) The readings will usually
not contain arguments in this nice form. Rather, you will have to extract premises and
conclusions from much more complex and lengthy passages of text. In doing this, it is
helpful to look out for certain key words which often serve as indicators of (“flags” for)
premises or conclusions.
Some common premise-indicators are
because, since, given that, for
words usually come right before a premise. Examples of the use of such “flags” for
Danish pastries should be renamed,
the Danish cartoonists committed
euthanasia is a common medical practice, we might as well make it
marijuana is a dangerous recreational drug, it should not be prescribed by
We must engage in affirmative action,
America is still a racist society.
gay marriage is a hotly contested issue in this country, nobody should
force his opinion about it on anyone else.
Some common conclusion-indicators are
thus, therefore, hence, it follows that, so,
. These words usually come right before the conclusion of the argument.
More exactly, sentences that are either true or false. Thus ‘Shut the door!’, and ‘Is the
door shut?’, although perfectly acceptable sentences, cannot form part of an argument as
Last revision: 2/12/09