Discussing an argument form
Choose one of these forms (EXCEPT APPEAL TO AUTHORITY) and discuss what can make for good arguments of that type. Provide at least one good example (in standard form) and one bad example of this type of argument, and explain what makes each of them good or bad. Be detailed in your explanations. How do we know if an argument of this form is strong or weak (or valid/invalid in the deductive case) in general? What can we do better to evaluate instances of this form when they occur in daily life? Cite any source you use, including the handout and the text.
Deductive versus Inductive Arguments
Hopefully, this post will help clarify the distinction between deductive and inductive arguments. If you have questions about the distinction, hit reply on this post.
There are two important aspects of deductive arguments, the form and the truth of the premises. A deductive argument can be defined as one that has a form which guarantees, IF the premises are true, the conclusion must also be true; that is, it’s impossible to accept the premises and to deny the conclusion. Consider the following example:
P1: All cats are mammals.
P2: Bella is a cat.
C: Therefore, Bella is a mammal.
It’s important that you see that if someone believes the two premises, then they would be contradicting themselves if they also believed that the conclusion was false. Notice the definition says “if the premises are true.” It’s possible for a deductive argument to have a false premise. For example, if the Bella mentioned in the above example was a dog, then premise 2 would be false, but the argument would still be deductive AND be valid.
An explanation of whether a deductive argument is good or bad should include a discussion of exactly how the premises lead to the conclusion and how if someone accepts the premises they are forced to also accept the conclusion. Identify the exact form (see the handout provided above) and explain why it matches that form. Explain why not accepting the conclusion would lead to a contradiction.
In contrast, an inductive argument can be defined as one that argues from statements (premises) about specific observations of part of a group or one event to a statement (the conclusion) about the entire group or type of event. With inductive arguments, it’s possible for the premises to be true and the conclusion to be false. In other words, denying the truth of the premises and accepting the true of the conclusion or accepting the premises and denying the conclusion doesn’t lead to a contradiction. Consider this example:
P1: Everyone I know likes coffee.
C: Therefore, everyone likes coffee.
The person giving this argument has observed everyone he or she knows and determined that they like coffee. From that, he or she concludes that everyone in the world likes coffee. While the premise may, in fact, be true, that doesn’t (as with deductive arguments) guarantee the truth of the conclusion. In fact, if one person does not like coffee (and we know there are many more than that), then we know the conclusion is false, even if the premise is true.
When explaining the strength or weakness of an inductive argument, focus on how well the premises support the conclusion. In our example above, if the person giving the argument only observed 5 people, then the argument is very weak. If the person observed 500 people, the evidence for the conclusion is stronger. If 5 million people were observed, then it’s even stronger evidence for the conclusion. But, unless every single person in the world (now, in the past, and in the future) has been observed and found to like coffee, the truth of the conclusion is never guaranteed by the premise.
[Notice that if we were able to observe everyone (past, present, and future) and determine they all liked coffee, then the inductive argument example would become:
P1: Everyone I’ve observed likes coffee.
P2: I have observed everyone.
C: Therefore, everyone likes coffee,
which would be a deductive argument because IF the premises are true, the conclusion cannot be false.]