Lecture: Analyzing Arguments
Lecture script · about 15–20 minutes spoken · Week 2
Opening
Picture a group chat for 4 roommates. It's 9 p.m., and one roommate writes, "We need a cleaning schedule. The kitchen has been a mess for 2 weeks, and nobody knows whose turn it is to take out the trash." Then silence. Everyone can feel that it's an argument. Everyone can also feel that something is missing between the reasons and the claim.
That feeling shows up everywhere: a nursing student checking what a care plan takes for granted, a business major reading a memo proposing a four-day week. Writing the argument out line by line, and supplying what it leaves unsaid, shows exactly what you're being asked to accept.
In Week 1, you learned to find an argument: its conclusion, the premises offered for it, and how it differs from an explanation. In this lecture, we take the next step. I'll show you how to lay an argument out in standard form, how to fill its gaps fairly, how to draw it as a map, and how to see it a second way with the Toulmin layout. Then we'll run all of it on the running question. Next, in Week 3, you'll start judging the arguments you lay out here.
1. Standard form
Start with a gym's flyer. It reads, "Why pay more somewhere else? Members who sign up this month pay no joining fee, and our new evening classes run until 10 p.m. Join this month." That's an argument, but its parts are scattered. One piece is a question. One is a command. The reasons are packed into one long sentence.
Think of a mechanic laying an engine's parts on a clean cloth before checking them. Nothing added, nothing thrown away.
The term for it is standard form. Standard form lists each premise on its own numbered line, P1, P2, P3; then a line that reads "So,"; then the conclusion on its own line, marked C. Indicator words are dropped, and every line is a complete declarative sentence.
That last rule does real work. A question or a command can't be true or false. So you rewrite it as the claim it carries, the way you learned to spot an implied claim in Week 1.
Let's lay out the flyer. The flyer wants you to join this month, so the conclusion becomes a claim: you should join this gym this month. P1: members who sign up this month pay no joining fee. P2: the gym's new evening classes run until 10 p.m. And the question, "Why pay more somewhere else?", carries a claim of its own. P3: other gyms cost more to join. Then the line "So," and then C.
Standard form didn't make the flyer more convincing or less. It put each claim where you can point at it, so you can say exactly which line you doubt.
Pause and try this. In the gym flyer, which line of standard form came from a question, and which came from a command?
Think about which sentences couldn't be true or false as written.
Here's the answer. P3 came from the question "Why pay more somewhere else?", and C came from the command "Join this month", because neither could sit on a line until it was rewritten as a claim.
One claim per line, and the conclusion goes last.
2. Unstated premises and conclusions
Back to the roommates. In standard form, the message says: P1, the kitchen has been a mess for 2 weeks. P2, nobody knows whose turn it is to take out the trash. So, C, the apartment needs a cleaning schedule.
Notice the jump. The premises describe a problem. The conclusion names a fix. Nothing on the page says this fix suits this problem. It's like a recipe that lists flour and eggs and then says "serve the cake", with no step about the oven. The writer knows the step. The reader has to fill it in.
Many everyday arguments leave a premise unstated because the arguer takes it for granted. An unstated premise is a premise an argument needs but leaves unsaid. When you write it out, you mark it "(supplied)" after its number, so no reader mistakes your words for the arguer's. A premise marked this way is a supplied premise.
For the roommates, the supplied premise could be this. P3 (supplied): a shared apartment should adopt a cleaning schedule when chores go undone because no one knows whose turn they are. Now the premises reach the conclusion, and you can see where a housemate might push back. Someone could accept P1 and P2 and still doubt P3.
Sometimes the conclusion is missing. A sandwich shop's sign says, "Every sandwich is made with bread baked this morning. You deserve fresh food." It never says "buy here", but that's the point. An unstated conclusion is a conclusion the arguer means to establish but never says out loud. You write it on the C line and mark it the same way.
Here's the trap. Once P3 is written down, it looks like every other line, and it's tempting to quote it back as something the roommate said. But the roommate never typed it.
Pause and try this. In the sandwich shop's sign, is the conclusion stated or unstated, and how should it be marked in standard form?
Ask whether the sign ever says what it wants you to do.
Here's the answer. It's unstated, so you write "you should buy your sandwiches at this shop" on the C line and mark it supplied, because the sign means it but never says it.
If you wrote it, mark it.
3. The principle of charity
Now a harder question. When more than one premise would close a gap, which do you supply?
Picture a bus rider at a city transit meeting. The rider says, "The night bus should run until 2 a.m. on weekends. Many restaurant workers finish their shifts after midnight." There's a gap. One premise that closes it says the city must run a bus whenever anyone wants a ride. Another says the city should extend bus service when a sizable group of riders has no other practical way home.
Both close the gap. But nobody thinks a city must run a bus for one person at 4 a.m., while the second is hard to dismiss and fits what the rider means.
That choice has a name. The principle of charity says that among the readings the words allow, you choose the one that makes the argument as reasonable as possible, and you supply the weakest premise that connects the stated premises to the conclusion.
"Weakest" doesn't mean flimsy. It means the premise that claims the least while still closing the gap, which gives the arguer the best fair chance. Think of it like tuning a guitar before you judge the song, so that later you're testing the real thing.
And charity has a hard limit. It rebuilds the argument the arguer actually gave. It never invents a view the arguer did not hold. If the rider said nothing about traffic safety, you don't add a premise about traffic safety to help. That would be your argument, not theirs.
And charity isn't agreeing. You can read an argument with full charity and still reject its conclusion.
Pause and try this. For the night bus, why does charity pick "service for a sizable group with no other practical way home" over "a bus for anyone at any hour"?
Compare how much each premise claims.
Here's the answer. Both close the gap, but the modest premise claims far less and fits what the rider meant, so it is the weakest premise that connects the reason to the conclusion.
The most reasonable reading, with nothing invented.
4. Argument maps
Standard form lists the parts. A map shows how they connect. An argument map is a drawing of an argument's structure with boxes for claims and arrows for support or attack. It's always described in words as well.
The biggest thing a map shows is whether premises work together or alone. Here's a rule from a restaurant kitchen. "Every staff member on the closing shift gets a free meal. The night cook is on the closing shift. So the night cook gets a free meal." Cover up either premise, and the other does nothing for the conclusion.
Those are linked premises: premises that support a conclusion only together, so that removing any one of them makes the support collapse. They get one arrow from joined boxes.
Now a memo from a team lead at a small design office. "We should try a four-day week this summer. Most of the team asked for it at the last staff meeting. Our two biggest clients close their offices one weekday each summer week anyway. And the office would spend less on cooling with one fewer day open." Cover up any one reason, and the others still give some support. Those are independent premises: premises that each give some support to a conclusion on their own. On a map, each one gets its own arrow.
So here's the test to carry: the cover-up test. Hide one premise and ask whether the others still give any reason for the conclusion. If they go quiet, the premises are linked. If they still speak, they're independent.
Maps also show disagreement. An objection is a reason offered against a premise or a conclusion, drawn as a box with an arrow marked "against". A reply is a reason offered against an objection, drawn as a box with an arrow marked "against" that points at the objection. At the design office, a client manager objects that customers who call on the closed day will get no answer. The team lead replies that the office phone can forward to one staff member on call. The objection points at the conclusion. The reply points at the objection.
Pause and try this. In the kitchen rule, should the two premises get one arrow from joined boxes or two separate arrows?
Cover one premise up and ask what the other still does.
Here's the answer. One arrow from joined boxes, because neither premise supports the conclusion alone, so they are linked.
Cover one up; if the other goes quiet, they're linked.
5. The Toulmin layout
Here's a second way to see structure. Toulmin's The Uses of Argument (1958) lays out an argument as a claim, the data offered for it, the warrant that links them, and the backing, qualifier, and rebuttal around them. The Toulmin layout is good at showing the hedges and exceptions that standard form can hide.
Let me walk through the six parts with a sports-radio host. The host says, "The home team will probably win this weekend. They have won their last 4 home games, and teams that keep winning at home tend to keep winning there, since they know the field and the crowd is behind them. Unless their starting goalkeeper is still injured, I like their chances."
The claim is what the host wants you to accept: the home team will win. The data are the facts offered: they've won their last 4 home games. The warrant is the general rule linking the data to the claim: teams that keep winning at home tend to keep winning there. The backing supports the warrant: they know the field, and the crowd is behind them. The qualifier is the word that says how strongly the claim is made: "probably". And the rebuttal is the exception that would defeat the claim: unless the goalkeeper is still injured.
Notice that the warrant does the same job as a supplied premise in standard form: it's the general link between the facts and the conclusion.
A warning, though. The Toulmin layout is a classroom tool for seeing structure. It isn't a test. An argument can fill all six boxes and still be weak, and nothing in this course is graded from the layout itself.
Pause and try this. In the sports-radio prediction, which word is the qualifier, and which part is the rebuttal?
Look for the hedge word and the exception.
Here's the answer. The qualifier is "probably", and the rebuttal is "unless their starting goalkeeper is still injured", because one says how strongly the claim is made and the other names what would defeat it.
Data needs a bridge to the claim; the warrant is that bridge.
6. The running question, laid out and mapped
Now let's put everything together on the running question, the illustrative newsletter passage about keeping the campus library open around the clock during finals week. The course takes no side.
Start with the conclusion. It goes last, on the line marked C: the campus library should stay open around the clock during finals week. The three stated reasons become premises. P1: during finals week many students need a quiet, safe place to study late at night. P2: the library is the only quiet, safe, well-lit study space on campus large enough to meet that need. And P4: keeping the library open overnight for the five nights of finals week costs about 1,600 dollars in staff wages.
Now find the gap. P1 and P2 say there's a need and a place that could meet it. But nothing stated says the campus ought to meet that need. So we supply one. P3 (supplied): the campus should provide study space students need during finals when it can do so at modest cost. It's the weakest premise that closes the gap, because it asks the campus to act only when the cost is modest. A premise that the campus must give students any space they ask for at any cost would also close the gap, but the writer never said it. Charity picks the modest version.
Let's count. Three stated premises plus one supplied premise is four premises. Four premises plus one conclusion is five lines in standard form.
And let's check the figure behind P4. Two staff times eight hours a night is 16 staff hours a night. Then 16 times five nights is 80 staff hours. And 80 hours times 20 dollars an hour is 1,600 dollars.
Now the map, in words. P1, P2, and P3 work together to support C, so they're linked, with one arrow from the joined boxes to C. P4 supports P3's "modest cost" condition, with its own arrow from P4 to P3. P4 isn't a fourth reason sitting beside the others; it holds up one part of P3.
The map also carries the strongest objection: overnight hours encourage all-night studying, and losing sleep can hurt exam performance, so the library would be helping students harm themselves. That's a box with an arrow marked "against" pointing at C. The reply says students who stay up will study somewhere, so the question is whether that place is quiet and safe, and the library can post sleep reminders and set aside one quiet floor for rest. That's a box with an arrow marked "against" pointing at the objection.
So here's the verdict in words. The argument has four premises, one of them supplied, and one conclusion. P1, P2, and P3 are linked, so the support for C collapses if any one of them fails. And the place to look hardest later is P3, the premise the writer never said out loud.
Mapping it isn't judging it; opponents and supporters should draw the same map.
Pause and try this. In the running question's map, which premise does P4 aim at, and why doesn't it aim straight at C?
Think about what P4's figure is meant to show.
Here's the answer. P4 aims at P3, because the 1,600 dollars supports P3's "modest cost" condition rather than giving its own reason for C.
P1, P2, and P3 hold up C together; P4 holds up P3.
Closing
Let me pull it together. Standard form puts each premise on a numbered line, then "So,", then the conclusion marked C, with every line a complete claim. An unstated premise or conclusion gets written out and marked supplied, because those are your words, not the arguer's. The principle of charity picks the most reasonable reading and the weakest premise that closes the gap, and it never invents a view or signals agreement. An argument map shows linked premises, which support only together, and independent premises, which each support alone, always described in words. The Toulmin layout is a second tool for seeing structure. And the running question now stands in five lines, with P3 supplied and P1, P2, and P3 linked.
Next in this module come the slide deck, the Readings and Resources page, the lecture tutorial, the practice set, and the quiz. Then, in Week 3, Deductive and Inductive Reasoning, you'll start judging the maps you drew, beginning with validity and the counterexample method.
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