An example Peer Instruction lecture
As an example Peer Instruction lecture, let's look at the second (1 hour) lecture in a first-year critical thinking course. The subject for the lecture is `identifying arguments'. The three main topics to be discussed are:
- Definition of argument: distinguisheing argument from assertion, denial and explanation
- Identifying arguments in texts by looking for conclusions
- Identifying arguments in texts by looking for premises
Students have already had the PI method explained to them and used it in the first lecture of the course.
A copy of the slides for this lecture are available: example-lecture.pdf .
The lecturer begins by giving a definition of an argument: an argument consists of a conclusion along with one or more premises; reasons for thinking that the conclusion is true. Giving an argument is then distinguished from asserting or denying something (without giving any reasons) or offering an explanation. Some simple examples are given to illustrate this distinction.
The topic of identifying arguments in texts is now introduced. The lecturer explains how arguments can be identified by looking for conclusion indicators words or phrases such as "thus', "therefore', "so', `it follows that' and so on. Some examples of arguments using these indicators are given.
In the absence of such indicators, a technique that can be used is to ask `what would make me believe this claim? What kind of evidence would I need to see in order to accept that claim?'. Then check to see if the author provides anything along those lines. If so, then you have found an argument. The lecturer illustrates this with an example containing an argument without conclusion indicators.
The lecture up to this point has taken approximately 15 minutes. The lecturer now shows the first quiz question:
Lecturer: OK, here is the first quiz question. Suppose you came across this in a magazine article. (Then reads out the following):
| Does the following passage contain an argument or not? Magazine article : Antitheft devices do not protect cars against thieves. Insurance industry statistics demonstrate that cars with alarms or other antitheft devices are more likely to be stolen or broken into than cars without such devices or alarms. A. Yes, this is an argument. |
Lecturer: OK, I'll give you a couple of seconds to think about it and then we'll all vote on the answer.
Students are now given about 25 seconds to think about their answer.
Lecturer: OK, everyone vote now.
All the students answer "A'.
Lecturer: Everyone is saying yes it is an argument, and you're all right. There are no conclusion indicators here, but what's the conclusion of this argument?
A few students answer at the same time: Antitheft devices do not protect cards against thieves.
Lecturer : Yes, the first sentence is the conclusion. And notice that if you applied the method of asking, when you read that first sentence, "what would make me believe that? What kind of evidence would I need to see?' you might answer something like "I'd like to see some statistics about how likely it is that cars with those kind of devices are stolen'. And that's more or less what the author goes on to provide.
The lecturer then asks whether students thought this was a good argument or not, which leads to a brief class-wide discussion of whether the premise is enough to establish the conclusion or not. This gives the lecturer the opportunity to briefly mention the principle of charity, which should be used when interpreting arguments.
Lecturer : Ok, what about this one? Again the question is whether there's an argument or not. (Then reads out the following):
| Does the following passage contain an argument or not? Often, accidents in the workplace occur because machine safety devices have been removed to improve productivity, or because workers have been given inadequate training or inadequate safety equipment. A. Yes, this is an argument. |
Students then get about 20 seconds to think about their answer.
Lecturer: OK, vote now. What do we think of that one?
This time nearly all the students answer B, with just one or two answering A. The lecturer decides there is not enough difference of opinion in the class for a discussion, so he confirms that the answer is B.
Lecturer: I think this is not an argument, this is an example of an explanation, or a statement about what causes something else. The claim is that the causes of workplace accidents are caused by two things: removing safety devices and inadequate training. But no actual evidence is given to support that claim - although they are plausible causes, no evidence is given here. OK, now the final question. (Reads out the following):
| Does the following passage contain an argument or not? … the difficult and most philosophically interesting question is how we should feel about death if it's the end. Is it a terrible thing to go out of existence? … it might seem that death can't have any value, positive or negative, because someone who doesn't exist can't be either benefited or harmed. A. Yes, the passage does contain an argument. |
This time the lecturer gives students a little longer to think about the answer (about 1 minute).
Lecturer: OK, so what do we think of this one? Vote "A' for yes there is an argument, "B' for no there isn't.
About 80% of students answer A.
Lecturer : OK, we do have a bit of a mixture here mostly As, 5 or 6s Bs. So what I'd like you to do now is turn to the person sitting next to you and try to convince them that your answer is the correct answer. So if you can find someone sitting near you who gave a different answer to you, talk to them about it for a minute.
There is now a buzz of conversation as students discuss the question with each other. After about 2 minutes and 30 seconds, the lecturer calls the discussion to a halt.
Lecturer : OK, so now let's vote again and see if any one has changed their mind. So everyone please hold up your cards, even if you haven't changed your mind.
Students vote again. There are now one or two more Bs than before, but the majority of students are still answering A.
Lecturer : OK, now we have may be a few more Bs than before. Interesting. Ok, so could someone who thought this isn't argument explain why?
Student: ... Well, at the start there isn't an argument...there's a question. Then at the end he says "it might seem that death can't have any value...' but I didn't take that to be an argument'.
Lecturer: Yes, OK. Did those of you who thought this wasn't an argument, think so for that reason, because of the phrase "it might seem that?' (Murmurs of agreement from the class). OK, that's fair enough. But suppose we ignore that part and just look at what follows: "death can't have any value BECAUSE someone who does not exist can't be either benefited or harmed'. Isn't that an argument?
Student: If you ignore that bit, there's an argument.
Lecturer : Yes, I think there IS an argument here. (Restates the argument). A clue that we have an argument is the indicator "can't'. We also have the word "because' which indicates a premise. So I think this author is mentioning an argument, but the force of the phrase "it might seem that' shows that they're not themselves endorsing this argument. In fact the author goes on to say, although you might think that death has no value for that reason, I disagree, for these reasons.
Student: So it's like he's pointing out that there's an argument there, but he's not taking sides.
Lecturer: That's exactly right, there's argument here, but he's not endorsing the argument....
Student : But does that make the passage an argument?
Lecturer : No, this person isn't giving argument, but there is an argument mentioned here. This is just something to be aware of; people writing about a topic might mention an argument without themselves endorsing it, because they want to go on to criticize the argument. So if you answered "No, there isn't an argument here' that's OK. The thing to notice is just that there is an argument here at the end that someone might give, but this author isn't endorsing that argument.
The lecturer then spends 15 minutes on the next part of the lecture, explaining how arguments can also be identified by identifying premises, using premise indicators such as "since', "because' and so on. Some examples are presented to illustrate this, along with some examples of the use of `because' to state causes, rather than introduce a premise. The lecturer then briefly summarizes all that has been said so far.
Lecturer: OK, so let's have some more quiz questions. In these questions, we'll have a argument and you have to say what the conclusion of the argument is. So let's look at this one. (Reads out the following):
| Calling any state totalitarian is misleading: it implies total state control of all aspects of life. The real world contains no political entity exercising literally total control over even one such aspect. This is because any system of control is inefficient, and, therefore, its degree of control is partial. Which one of the following most accurately expresses the main conclusion of this argument? A. No state can be called totalitarian
without inviting a mistaken belief. |
Lecturer: OK, so have a think about that for a minute and then we'll vote.
Students are given about 45 seconds thinking time.
Lecturer: OK, so let's vote on that one.
The answers are fairly evenly split between A and B, with one or two answering B.
Lecturer : OK, so we have about the same proportion of As and Bs, with a few Bs. So again, turn to the person sitting next to you and try to convince them that your answer is the right one.
Again there is a buzz of conversation as students discuss the question. After about three minutes of discussion, the noise level starts to drop off.
Lecturer: OK, so let's vote again on that one. Everyone vote again even if you haven't changed your mind. Hold up your cards please...
Now about 90% of students have the right answer (A), with one or two Bs and Cs.
Lecturer: OK, so now there are a lot less Bs, most people are answering A. There are still a few Cs. The right answer is A. The main conclusion is the first sentence; that calling a state totalitaian is misleading and the rest of the passage is telling you why that's true... However, if you notice the word 'therefore' at the end, that's introducing a conclusion. So this passage appears to have two conclusions...
Student: I thought an argument couldn't have more than one conclusion.
Lecturer : Yes, that's right. According to our definition of an argument, every argument has exactly one conclusion. So here we have a passage of text here which appears to have two conclusions in it. So what does that mean?
Several students answer at once: Two arguments.
Lecturer: Yes, two arguments. A passage of text might have more than one argument. Here we have two arguments which fit together; the conclusion of one argument works as the premise support the main conclusion of this argument. That's something we'll talk more about next time. You often get arguments that form chains, so that the conclusion of one argument is then used as the premise in a further argument. The main conclusion is the one that's right at the top of the chain. Let's finish there.