13.2: Logic and the Role of Arguments
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Critical thinkers tend to exhibit certain traits that are common to them. These traits are summarized in the following table:
Systematic by Method
Confident in Reasoning
Recall that critical thinking is an active mode of thinking. Instead of just receiving messages and accepting them as is, we consider what they are saying. We ask if messages are well-supported. We determine if their logic is sound or slightly flawed. In other words, we act on the messages before we take action based on them. When we enact critical thinking on a message, we engage a variety of skills including: listening, analysis, evaluation, inference and interpretation or explanation, and self-regulation.
Next, we will examine each of these skills and their role in critical thinking in greater detail. As you read through the explanation of and examples for each skill, think about how it works in conjunction with the others. It’s important to note that while our discussion of the skills is presented in a linear manner, in practice our use of each skill is not so straightforward. We may exercise different skills simultaneously or jump forward and backward.
Without an open-minded mind, you can never be a great success.
~ Martha Stewart
Critical thinking requires that we consciously listen to messages. We must focus on what is being said – and not said. We must strive not to be distracted by other outside noises or the internal noise of our own preconceived ideas. Although we have already explored listening, the type of listening you do critically is worth further discussion.
Listening becomes especially difficult when the message contains highly charged information. Think about what happens when you try to discuss a controversial issue such as abortion. As the other person speaks, you may have every good intention of listening to the entire argument. However, when the person says something you feel strongly about you start formulating a counter-argument in your head. The end result is that both sides end up talking past each other without ever really listening to what the other says.
Once we have listened to a message, we can begin to analyze it. In practice we often begin analyzing messages while still listening to them. When we analyze something, we consider it in greater detail, separating out the main components of the message. In a sense, we are acting like a surgeon on the message, carving out all of the different elements and laying them out for further consideration and possible action.
Let’s return to Shonda’s persuasive speech to see analysis in action. As part of the needs section of her speech, Shonda makes the following remarks:
Americans today are some of the unhealthiest people on Earth. It seems like not a week goes by without some news story relating how we are the fattest country in the world. In addition to being overweight, we suffer from a number of other health problems. When I was conducting research for my speech, I read somewhere that heart attacks are the number one killer of men and the number two killer of women. Think about that. My uncle had a heart attack and had to be rushed to the hospital. They hooked him up to a bunch of different machines to keep him alive. We all thought he was going to die. He’s ok now, but he has to take a bunch of pills every day and eat a special diet. Plus he had to pay thousands of dollars in medical bills. Wouldn’t you like to know how to prevent this from happening to you?
If we were to analyze this part of Shonda’s speech, we could begin by looking at the claims she makes. We could then look at the evidence she presents in support of these claims. Having parsed out the various elements, we are then ready to evaluate them and by extension the message as a whole.
When we evaluate something we continue the process of analysis by assessing the various claims and arguments for validity. One way we evaluate a message is to ask questions about what is being said and who is saying it. The following is a list of typical questions we may ask, along with an evaluation of the ideas in Shonda’s speech.
Is the speaker credible?
Yes. While Shonda may not be an expert per se on the issue of health benefits related to wine, she has made herself a mini-expert through conducting research.
Does the statement ring true or false based on common sense?
It sounds kind of fishy. Four or more glasses of wine in one sitting doesn’t seem right. In fact, it seems like it might be bordering on binge drinking.
Does the logic employed hold up to scrutiny?
Based on the little bit of Shonda’s speech we see here, her logic does seem to be sound. As we will see later on, she actually commits a few fallacies.
What questions or objections are raised by the message?
In addition to the possibility of Shonda’s proposal being binge drinking, it also raises the possibility of creating alcoholism or causing other long term health problems.
How will further information affect the message?
More information will probably contradict her claims. In fact, most medical research in this area contradicts the claim that drinking 4 or more glasses of wine a day is a good thing.
Will further information strengthen or weaken the claims?
Most likely Shonda’s claims will be weakened.
What questions or objections are raised by the claims?
In addition to the objections we’ve already discussed, there is also the problem of the credibility of Shonda’s expert “doctor.”
Inference and Interpretation or Explanation “Imply” or “Infer”?
For two relatively small words, imply and infer seem to generate an inordinately large amount of confusion. Understanding the difference between the two and knowing when to use the right one is not only a useful skill, but it also makes you sound a lot smarter! Let’s begin with imply. Imply means to suggest or convey an idea. A speaker or a piece of writing implies things. For example, in Shonda’s speech, she implies it is better to drink more red wine. In other words, she never directly says that we need to drink more red wine, but she clearly hints at it when she suggests that drinking four or more glasses a day will provide us with health benefits.
Now let’s consider infer. Infer means that something in a speaker’s words or a piece of writing helps us to draw a conclusion outside of his/her words. We infer a conclusion. Returning to Shonda’s speech, we can infer she would want us to drink more red wine rather than less. She never comes right out and says this. However, by considering her overall message, we can draw this conclusion.
Another way to think of the difference between imply and infer is: A speaker (or writer for that matter) implies. The audience infers. Therefore, it would be incorrect to say that Shonda infers we should drink more rather than less wine. She implies this. To help you differentiate between the two, remember that an inference is something that comes from outside the spoken or written text.
The next step in critically examining a message is to interpret or explain the conclusions that we draw from it. At this phase we consider the evidence and the claims together. In effect we are reassembling the components that we parsed out during analysis. We are continuing our evaluation by looking at the evidence, alternatives, and possible conclusions.
Before we draw any inferences or attempt any explanations, we should look at the evidence provided. When we consider evidence we must first determine what, if any, kind of support is provided. Of the evidence we then ask:
- Is the evidence sound?
- Does the evidence say what the speaker says it does?
- Does contradictory evidence exist?
- Is the evidence from a valid credible source?
Even though these are set up as yes or no questions, you’ll probably find in practice that your answers are a bit more complex. For example, let’s say you’re writing a speech on why we should wear our seatbelts at all times while driving. You’ve researched the topic and found solid, credible information setting forth the numerous reasons why wearing a seatbelt can help save your life and decrease the number of injuries experienced during a motor vehicle accident. Certainly, there exists contradictory evidence arguing seat belts can cause more injuries. For example, if you’re in an accident where your car is partially submerged in water, wearing a seatbelt may impede your ability to quickly exit the vehicle. Does the fact that this evidence exists negate your claims? Probably not, but you need to be thorough in evaluating and considering how you use your evidence.
A man who does not think for himself does not think at all.
~ Oscar Wilde
The final step in critically examining a message is actually a skill we should exercise throughout the entire process. With self-regulation, we consider our pre-existing thoughts on the subject and any biases we may have. We examine how what we think on an issue may have influenced the way we understand (or think we understand) the message and any conclusions we have drawn. Just as contradictory evidence doesn’t automatically negate our claims or invalidate our arguments, our biases don’t necessarily make our conclusions wrong. The goal of practicing self-regulation is not to disavow or deny our opinions. The goal is to create distance between our opinions and the messages we evaluate.
The Value of Critical Thinking
In public speaking, the value of being a critical thinker cannot be overstressed. Critical thinking helps us to determine the truth or validity of arguments. However, it also helps us to formulate strong arguments for our speeches. Exercising critical thinking at all steps of the speech writing and delivering process can help us avoid situations like Shonda found herself in. Critical thinking is not a magical panacea that will make us super speakers. However, it is another tool that we can add to our speech toolbox.
As we will learn in the following pages, we construct arguments based on logic. Understanding the ways logic can be used and possibly misused is a vital skill. To help stress the importance of it, the Foundation for Critical Thinking has set forth universal standards of reasoning.
Universal Standards of Reasoning
- All reasoning has a purpose.
- All reasoning is an attempt to figure something out, to settle some question, to solve some problem.
- All reasoning is based on assumptions.
- All reasoning is done from some point of view.
- All reasoning is based on data, information, and evidence.
- All reasoning is expressed through, and shaped by, concepts and ideas.
- All reasoning contains inferences or interpretations by which we draw conclusions and give meaning to data.
- All reasoning leads somewhere or has implications and consequences.
Logic and the Role of Arguments
We use logic every day. Even if we have never formally studied logical reasoning and fallacies, we can often tell when a person’s statement doesn’t sound right. Think about the claims we see in many advertisements today—Buy product X, and you will be beautiful/thin/happy or have the carefree life depicted in the advertisement. With very little critical thought, we know intuitively that simply buying a product will not magically change our lives. Even if we can’t identify the specific fallacy at work in the argument (non causa in this case), we know there is some flaw in the argument.
By studying logic and fallacies we can learn to formulate stronger and more cohesive arguments, avoiding problems like that mentioned above. The study of logic has a long history. We can trace the roots of modern logical study back to Aristotle in ancient Greece. Aristotle’s simple definition of logic as the means by which we come to know anything still provides a concise understanding of logic. Of the classical pillars of a core liberal arts education of logic, grammar, and rhetoric, logic has developed as a fairly independent branch of philosophical studies. We use logic everyday when we construct statements, argue our point of view, and in myriad other ways. Understanding how logic is used will help us communicate more efficiently and effectively.
When we think and speak logically, we pull together statements that combine reasoning with evidence to support an assertion, arguments. A logical argument should not be confused with the type of argument you have with your sister or brother or any other person. When you argue with your sibling, you participate in a conflict in which you disagree about something. You may, however, use a logical argument in the midst of the argument with your sibling. Consider this example:
Brother and sister, Sydney and Harrison are arguing about whose turn it is to clean their bathroom. Harrison tells Sydney she should do it because she is a girl and girls are better at cleaning. Sydney responds that being a girl has nothing to do with whose turn it is. She reminds Harrison that according to their work chart, they are responsible for cleaning the bathroom on alternate weeks. She tells him she cleaned the bathroom last week; therefore, it is his turn this week. Harrison, still unconvinced, refuses to take responsibility for the chore. Sydney then points to the work chart and shows him where it specifically says it is his turn this week. Defeated, Harrison digs out the cleaning supplies.
Throughout their bathroom argument, both Harrison and Sydney use logical arguments to advance their point. You may ask why Sydney is successful and Harrison is not. This is a good question. Let’s think critically about each of their arguments to see why one fails and one succeeds.
Let’s start with Harrison’s argument. We can summarize it into three points:
- Girls are better at cleaning bathrooms than boys.
- Sydney is a girl.
- Therefore, Sydney should clean the bathroom.
Harrison’s argument here is a form of deductive reasoning, specifically a syllogism. We will consider syllogisms in a few minutes. For our purposes here, let’s just focus on why Harrison’s argument fails to persuade Sydney. Assuming for the moment that we agree with Harrison’s first two premises, then it would seem that his argument makes sense. We know that Sydney is a girl, so the second premise is true. This leaves the first premise that girls are better at cleaning bathrooms than boys. This is the exact point where Harrison’s argument goes astray. The only way his entire argument will work is if we agree with the assumption girls are better at cleaning bathrooms than boys.
Let’s now look at Sydney’s argument and why it works. Her argument can be summarized as follows:
- The bathroom responsibilities alternate weekly according to the work chart.
- Sydney cleaned the bathroom last week.
- The chart indicates it is Harrison’s turn to clean the bathroom this week.
- Therefore, Harrison should clean the bathroom.
Sydney’s argument here is a form of inductive reasoning. We will look at inductive reasoning in depth below. For now, let’s look at why Sydney’s argument succeeds where Harrison’s fails. Unlike Harrison’s argument, which rests on assumption for its truth claims, Sydney’s argument rests on evidence. We can define evidence as anything used to support the validity of an assertion. Evidence includes: testimony, scientific findings, statistics, physical objects, and many others. Sydney uses two primary pieces of evidence: the work chart and her statement that she cleaned the bathroom last week. Because Harrison has no contradictory evidence, he can’t logically refute Sydney’s assertion and is therefore stuck with scrubbing the toilet.
Deductive reasoning refers to an argument in which the truth of its premises guarantees the truth of its conclusions. Think back to Harrison’s argument for Sydney cleaning the bathroom. In order for his final claim to be valid, we must accept the truth of his claims that girls are better at cleaning bathrooms than boys. The key focus in deductive arguments is that it must be impossible for the premises to be true and the conclusion to be false. The classic example is:
All men are mortal.
Socrates is a man.
Therefore, Socrates is mortal.
We can look at each of these statements individually and see each is true in its own right. It is virtually impossible for the first two propositions to be true and the conclusion to be false. Any argument which fails to meet this standard commits a logical error or fallacy. Even if we might accept the arguments as good and the conclusion as possible, the argument fails as a form of deductive reasoning.
Another way to think of deductive reasoning is to think of it as moving from a general premise to a specific premise. This form of deductive reasoning is called a syllogism. A syllogism need not have only three components to its argument, but it must have at least three. You can begin with a major premise, progress to your minor premise, and then to your conclusion. We have Aristotle to thank for identifying the syllogism and making the study of logic much easier. The focus on syllogisms dominated the field of philosophy for thousands of years. In fact, it wasn’t until the early nineteenth century that we began to see the discussion of other types of logic and other forms of logical reasoning.
It is easy to fall prey to missteps in reasoning when we focus on syllogisms and deductive reasoning. Let’s return to Harrison’s argument and see what happens.
- Girls are better at cleaning bathrooms.
- Sydney is a girl.
- Sydney should clean the bathroom.
Considered in this manner, it should be clear how the strength of the conclusion depends upon us accepting as true the first two statements. This need for truth sets up deductive reasoning as a very rigid form of reasoning. If either one of the first two premises isn’t true, then the entire argument fails.
Inductive reasoning is often thought of as the opposite of deductive reasoning; however, this approach is not wholly accurate. Inductive reasoning does move from the specific to the general. However, this fact alone does not make it the opposite of deductive reasoning. An argument which fails in its deductive reasoning may still stand inductively.
Unlike deductive reasoning, there is no standard format inductive arguments must take, making them more flexible. We can define an inductive argument as one in which the truth of its propositions lends support to the conclusion. The difference here in deduction is the truth of the propositions establishes with absolute certainty the truth of the conclusion. When we analyze an inductive argument, we do not focus on the truth of its premises. Instead we analyze inductive arguments for their strength or soundness.
Another significant difference between deduction and induction is inductive arguments do not have a standard format. Let’s return to Sydney’s argument to see how induction develops in action:
- Bathroom cleaning responsibilities alternate weekly according to the work chart.
- Sydney cleaned the bathroom last week.
- The chart indicates it is Harrison’s turn to clean the bathroom this week.
- Therefore, Harrison should clean the bathroom.
What Sydney does here is build to her conclusion that Harrison should clean the bathroom. She begins by stating the general house rule of alternate weeks for cleaning. She then adds in evidence before concluding her argument. While her argument is strong, we don’t know if it is true. There could be other factors Sydney has left out. Sydney may have agreed to take Harrison’s week of bathroom cleaning in exchange for him doing another one of her chores. Or there may be some extenuating circumstances preventing Harrison from bathroom cleaning this week.