Evaluating Premises and Conclusions: An Overview.
So far ,you know that arguments are made up of a conclusion
and the premises offered to defend or uphold it.
Some arguments are deductive,
that is, if the premises are true and the former the argument is valid,
then the conclusion has to be true and the argument is sound.
Other arguments are inductive. An
inductive argument if the premises are either true
or at least acceptable remember that means that
their relevant to the issue at hand and provide sufficient justification
then the conclusion is likely to be true and we consider these inductive
arguments to be strong
in questioning both types of arguments
there are a number of evaluations you can make to determine the soundness
or strength up the argument in this module
you learn about two main ways to evaluate an argument
first you'll hear about how to evaluate premises
in and of themselves on their own merits then
you learn how to evaluate the logical link that connects the promises to the
conclusion
this module provides an overview of the key evaluation approaches you should use
to assess
any argument you encounter later modules will dig deeper into each approach
and explain how you can effectively use the techniques to evaluate different
types of arguments
evaluating promises truth and acceptability
premises supply the evidence on which an argument is based
and their strength can range from the strongest promises that are
straightforward facts
such as the Earth revolves around the Sun to weaker premises
my personal opinions are value judgments can like your friend saying
this music is awful one standard for evaluating a promise
is to determine whether it's true or false we can use observed or empirical
evidence
that is things we see touch hear smell taste and so on
to figure out whether certain kinds of promises are true
now it may not be easy to determine the truth repress
for a lot of early human history proving that the earth revolved around the
son was quite difficult but we at least know how we're supposed to go
determining its truth which means proving or disproving the premise
sometimes while it may be possible in
theory to actually observe the truth to the Primus it may be
practically speaking impossible to do so for example
take the claim that all swans are white in order to definitively proved this to
be true
we would be defined every single Swan on the planet to see what color it is
a daunting task especially considering more swans are being born all the time
however we could rely on Swan experts
conducting research involving as many Swan says is reasonable
and investigating aspects aswan biology
to Tolleson experts view once one color while we wouldn't prove that the premise
was true
we could judge it to be more or less acceptable
in addition to hard to prove
empirical claims there are other promises that cannot be evaluated on
whether they're true or not
promises that relate to a static moral or ethical claims
fall in that category opinions in value judgments
represent personal cultural communal social and religious perspectives
and police these by their very nature cannot be proven or disproven
however that does not mean that they cannot
or should not be subjected to scrutiny and evaluation to determine
whether they provide acceptable reasons for agreeing with the particular
argument
throughout your personal academic and professional life
you grapple with the number of arguments based on opinions or value judgments
you should resist the temptation to simply say
well everyone's entitled to their own opinions and to accept all such argument
is equally possible
there are many important issues and problems about what you'll find serious
disagreements
critical thinking is meant are you with the tools and resources to carefully
consider those arguments
assess the relative strengths and weaknesses and come to an informed in
considered opinion
above which one you believe to be true were reasonable relating promises
and conclusions validity relevance insufficiency
it's not enough to simply evaluate individual promises to determine their
truth or acceptability
consider the following argument the sky is blue
therefore I should wear sunglasses when I'm outside
now it is true that the skies blue
but a reasonable person might wonder what in the heck does the sky being blue
have to do with wearing sunglasses
the truth the premise does not necessarily guarantee that you're
dealing with a valid
argument instead consider an argument that says
the Sun is bright I should make sure to wear my sunglasses today
now this argument seems much stronger
and it is stronger because one the premise
years or can be determined to be upon visual examination
true and two there's a reasonable connection
between brightness and the wearing sunglasses remember that deductive
arguments are those were the true to the premise
can lead to a valid conclusion so when evaluating deductive arguments
you should look for whether the former the argument is valid
a deductive argument has a valid form if it is
impossible for the premises to be true and the conclusion to be false
so to illustrate this consider an example of an argument with an
invalid for your friend tells you the old business building is worn out
and it's unsafe so we should tear it down for the safety of the students
while the premise is that the building is old and safe
are true they don't necessarily lead to the conclusion
that the building has to be torn down one obvious alternative
is that repairs could be made to make the building safe in this case
even though the premise is true it's still possible for the conclusion to be
false
because it's not necessarily related to the promise now
think about this alternative example that has a valid for
your friend says your business buildings and safe because it doesn't have a fire
alarm system
which makes it unsafe so we should install a fire alarm system for the
safety the students
here
clearly if the premise is true then the conclusion
must also be true for
inductive arguments two separate standards must be used to evaluate
arguments logical validity relevance and sufficiency
instead of the true or not standard used for deductive arguments
inductive arguments rely more or less on acceptable promises to make them
stronger or weaker
this makes the relationship between the premises and conclusions
much more complicated it's not the case that a premise
you judge to be true conserve on its own to defend a conclusion
instead you're dealing with promises better
often opinion rather than fact and these premises have a range in their
acceptability
so one thing you must do in evaluating an inductive argument
is the first figure out if the premises are relevant to the issue at hand
and the conclusion that strong imagine your professor asked the class
should I hold a review session before the midterm exam
your classmate responds by saying no you shouldn't
the text book for this class was really expensive now the claim that the
textbook was expensive
maybe a perfectly acceptable claim but doesn't have
anything to do with the conclusion that there should not be a review session
consider an alternative response no you shouldn't
my friends in the other section in this class and they aren't having a review
session
I don't think it would be fair if we have one in this case
you will still want to evaluate the acceptability of the premises about
fairness
but it is clear that there is a connection between the premises
and the conclusion in addition to figuring out whether the premises are
relevant
you must also assess whether they are sufficient
that means you must think about whether the claims made promises
or enough to justify the conclusion let's go back to the second response on
the midterm review question
the one we're classmate says no we shouldn't my friends in the other
section and they are having a review session
let's say you determine the following things one
it is true that the other section is not having a river
you to fairness between sections is a reasonable
and acceptable thing to be concerned about in three
what's happening in the other section is relevant for your class
Joe's at it do you accept your classmates argument is strong enough
or might you instead say well I see your point
it is important to be fair and I feel bad that the other class won't get to
have a review
but why should we suffer too that's not a good enough reason
essentially you're saying that your classmates premises are not sufficient
reasons to accept his conclusion
that is it's not enough to justify the conclusion
now you should have some idea of how to go about evaluating deductive
an inductive arguments you should examine the premises themselves
and tried to determine whether they're true acceptable then
you need to consider the connection between premises and conclusions
are the promises relevant to the issue and the conclusion reached
or the sufficient to justify that conclusion knowing to ask these
questions
is an important step in critical thinking in later modules
you learn more about how to answer these questions