Premises

Transcription

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