Logic and Scientific Thinking

Premises and Conclusions

Bogdan G. Popescu

bgpopescu@tec.mx

Tecnologico de Monterrey

Learning Outcomes

Overview

Spot conclusions and premises — in writing and in speech.

Tell arguments from assertions, contradictions, and explanations.

Rebuild arguments in standard form — hidden premises included — and locate the weakness: a premise, or the therefore.

NARRATION: Welcome. By the end of today you’ll be able to do three things: find the conclusion and the premises in anything you read or hear; tell a real argument apart from insults, flat denials, and mere explanations; and rewrite an argument in what we’ll call standard form — including the premises nobody says out loud — then point at exactly where it’s weakest. Everything today builds toward those three skills. Timing plan, honest numbers (180-min slot). The Argument Clinic block is commented out of the deck; restore it and add ~18. Outcomes ~4 / Recap: Quick Logic Check ~3 / What an argument is + is not ~12 / Part 2 (debate: clip + replay 6, Steps 1-6 ~15, flood pair ~6, Step 8 exercise + share-outs ~15, Step 9 ~4) ~45 / BREAK 15 / Part 3 (toolkit, incl. the charity example) ~14 / Exit check ~5 / Close ~4. Total ~102; ~78 slack. Two in-class exercises: Argument by Ear (clip), Step 8 repair — both get full time in this session; no accordion should be needed. DEFAULT CUT if somehow behind (decided now, not live): trim Step 8 share-outs to three pairs and show Step 9 in 60 seconds. Three outcomes only, matched to what the exit check tests. Repair (Step 8) and charity are deliberately activities, not formal outcomes — don’t promise them on slide one. The CLOSING slide does name repair: that is a report of what they did, not a promise, and the distinction is intentional — keep it. Next session: kinds of claims, Hume, Euthyphro, team activity. Outcome 3’s “locate the weakness” seeds the next session’s “judge the weakest point.”

Recap: The Quick Logic Check

Question	From the previous session
The conclusion?	The claim after “therefore”
The premises?	The reasons actually given
The unstated assumption?	What connects them — never said aloud

Vitamin C: true premises, undecided conclusion. Today we hunt that weakness in real material.

What Is an Argument?

An argument has two essential elements:

The conclusion — the claim you want people to accept.
The premises — the reasons you give people to accept it.

“It is going to rain. Therefore, take an umbrella.”

One premise, one conclusion.

NARRATION: Now the definition, officially. For today, an argument has two essential elements: at least one premise — the reasons — and a conclusion — the claim those reasons are meant to establish. The smallest argument in the world: it is going to rain, therefore take an umbrella. That’s it — two elements, nothing more. Everything else today is learning to see these two elements in messier and messier places. For reconstructions this week: ONE principal conclusion per argument — chained sub-conclusions come later. Mention it here verbally; it becomes visible in Part 3’s worked reconstruction. WHY ARGUMENTS EXIST AT ALL, one sentence worth saying (Mercier & Sperber 2017): “reasons are primarily for social consumption” — we produce them to justify ourselves to EACH OTHER and to evaluate what others tell us. The course is largely training the evaluation side — the side humans are demonstrably good at.

Indicator Words

Premise indicators	Conclusion indicators
because, since, for, given that	therefore, thus, so, hence
as shown by, the reason is	it follows that, this shows that

Warning: indicator words are clues, not guarantees.
e.g. “Since 2020, inflation has risen”
since indicates time, not a premise.

What is Not an Argument

A description — “It is raining outside.”
It states a fact but gives no reason for another claim.
An opinion — “Messi is the greatest football player ever.” It expresses a judgment but provides no supporting reasons.
A contradiction — “No, it isn’t.” It targets the claim but offers no reason. One word would fix it: because.
An explanation — “I was late because there was heavy traffic.” It explains why an accepted event occurred rather than trying to prove that it occurred.

NARRATION: Four things that look like arguments but are not. A description just says what is — nothing to prove. An opinion, like “Messi is the greatest ever,” is a conclusion with no reasons attached — it feels like a debate, but nobody has argued yet. A contradiction — “no, it isn’t” — at least aims at the claim, but it gives zero reasons; you can say no without listening and without thinking. One word would fix it, and you just saw it in the table: the moment “no, it isn’t” becomes “no, it isn’t, because…” a contradiction starts becoming an argument. And an explanation gives a cause for a fact nobody disputes — we all agree I was late; the only question is why. Same test every time: did anyone give reasons, for a claim in dispute? If the Messi line sparks a “no he isn’t!” — point at it: that reply is the contradiction bullet, live in the room.

The Tricky Case: Explanation vs. Argument

Both can use “because.” The key question is: what job are the reasons doing?

flowchart LR
  Q{"the reasons<br/>are there to..."} -->|"...give you a reason to<br/>BELIEVE the claim"| A["Argument"]
  Q -->|"...tell you WHY<br/>it happened"| E["Explanation"]

“The metro was delayed because of the storm.” → explanation — the delay is taken as given; the storm tells us why it happened.

“The results can’t be trusted, because the polls were fabricated.” → argument — the fabricated polls give us a reason to believe that the results are unreliable.

Shortcut: Argument = Why should I believe this?
Explanation = Why did this happen?

NARRATION: This is probably the trickiest distinction because arguments and explanations can both use words like “because.” The key is not the word “because.” Ask what job the reason is doing. In an argument, the reason gives you evidence or support for accepting a claim. The question is: “Why should I believe this?” In an explanation, we are trying to account for something. The question is: “Why did this happen?” or more generally, “Why is this the case?” Take the metro example. We are not using the storm as evidence that the metro was delayed. We already accept that the metro was delayed. The storm explains why. In the polling example, “the results can’t be trusted” is the conclusion we are being asked to accept. The fact that the polls were fabricated gives us a reason for accepting that conclusion. One qualification: whether a claim is disputed or already accepted is only a useful clue, not the definition. An argument can support something nobody disputes, and an explanation can concern something that is itself disputed. What ultimately matters is the FUNCTION of the reason: is it supporting a claim, or accounting for why something is the case?

The Tricky Case: Explanation vs. Argument

Both can use “because.” Don’t look at the word because. Ask:

What are we trying to establish?

Argument: one claim is used as evidence that another claim is true.
Explanation: one fact is used to account for why another fact happened.

“The metro was delayed because of the storm.”
→ Explanation — the delay is the thing being explained.

“There must have been a storm because the metro was delayed.”
→ Argument — the storm is the thing we are trying to establish.

Shortcut:
Argument = What should I believe?
Explanation = What caused this?

Part 2: Argument by Ear — the Debate

Practice: Argument by Ear

October 2012: President Barack Obama, seeking re-election, debates his challenger Mitt Romney live on TV

a fixture of US elections, where a moderator asks and the voters judge.
The moderator’s question
Romney’s answer
Obama’s reply

Practice: Argument by Ear

Before we discuss, write:
1. Argument — or something else?
2. The conclusion, in your own words.
3. The premises actually offered.
4. Any hidden premise the argument relies on.

NARRATION: Now watch the clip — about two minutes. Before we discuss it, write four things: Is this an argument, or something else? What is Obama’s conclusion, in your own words? What premises does he actually offer? And — hardest — is there a hidden premise doing silent work? Pause here, watch it twice if you need to, and write your answers before moving on. Spoken arguments bury their structure; that is the point of the exercise. ORIENT FIRST, 15 seconds, before pressing play: your students were about five years old in 2012 — say aloud that Obama is the sitting president running for re-election, Romney the Republican challenger, and that US candidates debate live on TV before the vote. Without this, confusion about context masquerades as difficulty with argument. The foreignness is otherwise a feature: nobody in the room has a team. Obama-Romney, third debate, 2012 — teaching cut (2:11): Schieffer’s money question (0:00), Romney’s ships argument (0:11), Obama’s reply (1:02); the “website” zinger is cut. Embedded from Dropbox; OFFLINE BACKUP: media/horses_bayonets.mp4 (embedded captions) — TEST IT EACH TERM. Key passage 1:15-1:46; with weak listeners, play that stretch twice — this session has the time. EN/ES transcripts in media/ to print as handouts. One visible splice at 0:11 — say “I trimmed the detours” up front; it models honest editing. ANSWER KEY (Obama’s reply): Conclusion — “fewer ships than in 1917” is a misleading measure; judge the military by what it can do. Premises: the nature of the military has changed; we now have aircraft carriers and nuclear submarines (and fewer horses and bayonets). HIDDEN PREMISE: strength is measured by capability, not by counting units — never stated, only demonstrated through examples. Bonus precision beat: Romney says “1917,” Obama repeats it as “1916” — even careful listeners mangle premises. Debrief line: spoken arguments drop the indicator words and bury the conclusion mid-sentence — that is why reconstruction is a skill, not a reflex. Honest timebox for the full block (clip + Steps 1-9 + flood pair + Step 8 with real share-outs): ~45 minutes. That is the point of the two-session split — do not sprint it.

Step 1: Romney’s Claim

The moderator: “You want a bigger military… where are you going to get the money?”
Romney: “Our Navy is smaller than 1917… I will not cut our military budget.”

Premise 1: The Navy has fewer ships than in 1917
Premise 2: If the Navy has fewer ships, it has insufficient capability
Conclusion: I will not cut the military budget.

Remember the question: “Where are you going to get the money?”

NARRATION: Step one: get Romney’s argument on the table, fairly. The moderator asks: where will the money come from? Romney’s conclusion: I will not cut the military budget. His reasons: the Navy has fewer ships than in 1917 — and, stronger, the Navy itself says it needs 313 ships and has only 285. Notice Romney is genuinely arguing: a claim, plus reasons. And keep the moderator’s question in your pocket — where is the money coming from? Nobody has answered it yet. ~90 s. The setup slide: establish that Romney argued properly — it makes Obama’s move more interesting and keeps the debrief non-partisan. Cold-call: “Was Romney arguing, or just asserting?” Precision beat if it comes up: Romney never claims imminent danger — his premise is RISK (“less certain and less secure”), not threat. Risk arguments are much harder to refute than threat arguments (you can’t disprove “less safe” by pointing at peace), which is partly why Obama attacks the ship count instead of the safety premise.

Step 2: Obama’s Response

Moderator: “You want a bigger military… where are you going to get the money?”
Romney: “Our Navy is smaller than 1917. I will not cut our military budget.”
Obama: “The question is not about counting ships. It’s: what are our capabilities?”

Premise 1: Military technology has changed since 1917.
Premise 2 (unstated): Fewer ships than in 1917 does not mean that the military is weaker.
Conclusion: The Navy is not weaker or inadequately funded.

Obama proposes a redefinition of the question: “what are our capabilities?”

Step 2 Obama’s Response

Two ways to answer an argument:

“Premise is false”
“Premise is disconnected from the conclusion.”

flowchart LR
  P1["Romney's stated premise<br/>The Navy has fewer ships<br/>than in 1917<br/><i>Obama accepts this</i>"]
  P2["Romney's hidden premise<br/>Fewer ships means<br/>less capability or<br/>inadequate funding"]
  C["Romney's conclusion<br/>Do not cut<br/>the military budget"]

  P1 --> P2
  P2 --> C

  O["<b>Obama attacks here:</b><br/>ship counts across different<br/>technological eras are not<br/>a reliable measure of capability"]
  O -.->|"challenges"| P2

  style P2 stroke:#b00000,stroke-width:3px
  style O fill:#40666e,color:#ffffff,stroke:#40666e

Step 3 — The Hidden Premise

Put the argument together — something is still missing:

P1.	The military has changed since 1917.
	↳ evidence: we now have aircraft carriers and nuclear submarines.
P2.	Having fewer items than in 1917 does not necessarily mean having less military capability.
	↳ evidence: we also have fewer horses and bayonets, without being weaker.
P3.	Raw equipment counts are not reliable measures of strength when equipment has changed.
C.	“Fewer ships than 1917” tells you nothing about strength.

His examples show his premises and how he gets to the conclusion

NARRATION: Now assemble the argument — and notice something is still missing. P1: the military changed since 1917 — and the carriers and submarines are the evidence for that, not a separate premise. P2: fewer horses and bayonets, and no weaker for it. Even with both, the conclusion does not follow — until you add P3: ships are like horses and bayonets; their count does not measure what the military can do. Try it physically: cover P3 with your hand — two facts, no conclusion. Cover P2 instead — P3 has nothing standing behind it. The hidden premise is the bridge. And Obama never says it; his examples only show it. That is what makes hidden premises hard to catch, and worth catching. This is question 4’s answer. The evidence-vs-premise point is worth a beat: “carriers and submarines” backs P1; it is not a third reason for the conclusion. The cover-it-with-your-hand move is the teachable gesture — reuse it in Part 3. P3 is deliberately worded as the ANALOGY LICENSE (“ships are like horses”), not as the general principle “strength = capability” — the general principle would entail C on its own and leave P1–P2 idle. Worded this way, the cover test works in both directions, and Step 5’s Problem 3 attacks exactly this premise (horses were replaced; ships were not).

Step 4 — Potential Problems, Both Sides

Now the argument is laid out — and you can see exactly where to attack it:

The reframe: Obama declares that navy counts don’t measure strength.
The ignored premise: he rebuts the weak point (“1917”) and dodges the strong one: Navy needs 313 ships, has 285.
The analogy: horses were replaced by tanks; ships were replaced by nothing. Does it carry over?
Romney assumes too: that a 1917 ship and a 2012 ship are the same unit. They aren’t.
The small insult: the reply also includes a jab at Romney — the person, not the claim.

NARRATION: With the argument laid out, the attack points become visible — on both sides. One: the reframe. Who decided the question “is not about counting ships”? Announcing the question just asserts P3 — that counts don’t measure strength — without arguing for it. Two: the ignored premise — Romney’s strongest point was the Navy’s own 313-versus-285 assessment, and Obama never answers it; he mocks the weak premise instead. Three: the analogy — horses were replaced by tanks and trucks; ships were not replaced by anything. Four: Romney’s side has a hidden premise too — that a 1917 ship and a 2012 ship are the same kind of unit. And five: a small insult, riding along. Both men argued; both arguments have soft spots; the tools found them without taking a side. Balance is the point: both men argued, both arguments have soft spots, and the tools found them without taking a side. PAYOFF of the money question from Steps 1–2: the moderator asked WHERE THE MONEY COMES FROM. Romney answered “why the military needs more”; Obama answered “why counting ships is wrong”. Nobody answered — the whole exchange is a double reframe. Cash this after Problem 1 if the room is following.

Step 5 — Two Deeper Lessons

Refuting is not proving.
- Breaking Romney’s argument does not make Obama’s budget right.
They agree more than they admit.
- Both want a strong military.
The real dispute is narrow:
- how do we measure military strength

NARRATION: Two deeper lessons before we move on. First: refuting is not proving. Even if Obama completely breaks Romney’s argument, that does not make his own budget right — winning the attack does not win the argument. Second, and stranger: they agree more than they admit. Both want a strong military; the real dispute is narrow — which measure, and who pays. That is what a reconstruction gives you: not who won, but where the battle actually is, and how much was shared ground all along. Cold-call to open: “Do Obama and Romney actually disagree? About what, exactly?” Let the room discover the shared premise before revealing bullet 2. Lesson 1 is the general principle to name slowly: winning the attack does not win the argument — students will meet it again as “argument from fallacy” territory in a future session. If pressed on lesson 1, the concrete version: even if counting ships IS the wrong measure, “adjust to needs” could just as well mean MORE ships — the Navy’s own 313-ship figure is itself a needs claim.

Your Turn: Repair the Debate

A new job. - Until now you reconstructed - Now you repair: - build the stronger argument he could have made.

You are Obama’s debate coach. Rewrite his 30-second reply — three sentences. It must:

Answer Romney’s strongest premise — the Navy’s assessment: 313 ships needed, 285 in the fleet. (Answer it — don’t counterattack it.)
Answer the moderator: where does the money come from?
Show the conclusion with a visible because.

Facts you may use (or invent a plausible number):

The 313 target dates from 2005.
The Joint Chiefs review military needs regularly.
A 5% cut elsewhere saves ~$30B/year.
Romney’s plan costs ~$200B/year.

5 minutes.

NARRATION: Now it is your turn — and notice the job changes. Until now you were reconstructing: making explicit what was said. Now you will repair: build the stronger argument he could have made. You are Obama’s debate coach. Rewrite his thirty-second reply in three sentences. It must answer Romney’s strongest premise — the Navy’s own 313-ship assessment — not counterattack it. It must answer the moderator’s money question. And it must show its conclusion with a visible “because.” Use the fact bank on the slide, or invent plausible numbers — we grade the shape, not the policy. Pause here and actually write it. This is the skill. This is the session’s construction moment (repair is an activity, not a formal outcome): Steps 1-6 run backwards — each constraint is a Step 5 problem turned into a requirement. The fact bank exists because constraint 2 otherwise demands US policy knowledge they don’t have — the skill being graded is assembly of reasons, not fiscal expertise. Circulate for the counterattack failure anyway; the parenthesis on the slide won’t stop everyone. During share-outs, cold-call a listener per reading for the three-box verdict — that is the evaluation rep. In this session there is TIME: take five or six pairs, not two.

The Repaired Debate

MODERATOR: “You want a bigger Navy — where are you going to get the money?”

ROMNEY, repaired (our repair — built from material he used elsewhere in the debate):

Answers the question: “From cuts elsewhere: I will cut 5% of what the government spends outside the military, and hand some programs to the states, which run them more cheaply.”
Gives his strongest reason: “And the Navy needs it, because the Navy’s own 2005 assessment set the requirement — 313 ships for its missions — and today it has only 285.”

OBAMA, repaired (our repair):

Engages the strongest premise: “That 313 figure is seven years old. The Joint Chiefs re-examined the missions with today’s capabilities and set the fleet my budget funds — because the requirement should come from current missions, not from a 2005 target.”
Attacks Romney’s money answer: “Do the math with me: that 5% saves about $30 billion a year. His military promise costs about $200 billion a year. Thirty does not pay for two hundred — the math doesn’t work. Mine keeps spending steady, fully paid for.”

What the Repair Changed

Still opponents. They disagree about:
- the requirement (valid or outdated?)
- the arithmetic (does the money cover it?).

But both answer the question asked.
Both attack the strongest version of the other side.
Both leave their because visible.

NARRATION: Look at what the repair changed — and what it did not. They are still opponents: they disagree about the requirement and about the arithmetic. But now both answer the question asked; both attack the strongest version of the other side; both leave their “because” visible. Good arguing did not produce agreement — it produced a disagreement worth having. And notice what vanished: the 1917 comparison and the bayonets joke. The famous lines belonged to the bad version. The viral moments were the bad-argument moments. Show AFTER pairs share, never before — it anchors. Present as “one way,” not “the answer”: different money answers (other cuts, taxes) are equally valid if the constraints are met. Honesty beat worth saying aloud: Romney’s repaired money answer is REAL — he gave it in the part of the debate we trimmed, before the moderator pulled him back to the military. The repair is partly a restoration — and both are labeled as REPAIRS on the slide, not reconstructions; keep the vocabulary clean. Full taxonomy if a student asks: RECONSTRUCTION makes explicit what was said or presupposed; REPAIR builds the better argument they could have made; ADVOCACY supplies new evidence and argues it yourself — today stops at repair. Complicate the cynicism: politicians do sometimes answer; editing (including ours) shapes what you see. Also point out what VANISHED in the repair: the 1917 comparison and the bayonets joke — both famous lines, both gone, because both belonged to the bad version. The viral moments WERE the bad-argument moments. (This is why Obama’s repaired reply engages the 313 requirement directly: a current needs figure already counts carriers and submarines, so no cross-era comparison can answer it.) “The math doesn’t work” is also real Obama, restored from the trimmed segment — both repairs recycle authentic material. The 2005 date is factual too: the 313-ship goal comes from the Navy’s 2005 Force Structure Assessment, and by 2012 the Navy had revised its target — Romney never said the year; the repair adds TRUE specificity, which is what charitable reconstruction is allowed to do. The money numbers are round but real: US non-military “day-to-day” spending was ~$600B/yr in 2012 (5% ≈ $30B); Romney’s 4%-of-GDP defense pledge was estimated at ~$2 trillion over a decade (≈ $200B/yr). The slide deliberately avoids the words “discretionary” and “Medicaid” — the arithmetic 30-vs-200 IS the argument, and students can check it themselves. And note the repaired debate is STILL a fight: good arguing did not produce agreement; it produced a disagreement worth having.

The Flood

How many checkable claims did you hear in the video?

1917 · 313 ships · 285 ships · “the low 200s” · sequestration · the Air Force since 1947 · FDR · two conflicts at once · a trillion dollars · Congress proposed it · “it will not happen” · maintaining spending · 1916 · horses · bayonets · aircraft carriers · nuclear submarines · the Joint Chiefs · veterans’ support · “your budget doesn’t work”

In those keywords: a claim about every 7 seconds.

Checking one claim takes longer than making ten.
Every unchecked claim feels like a point scored
When checking is hard, what decides is confidence (and joke).

Some debaters use flooding to their advantage

NARRATION: Now, the uncomfortable part. In those two minutes you heard a checkable claim roughly every seven seconds — look at the wall of them. Some of those terms mean nothing to you: sequestration, FDR, the Joint Chiefs. Here is the thing — they meant little to most American viewers too, at that speed. Feeling lost in the wall is not a language problem; it is the flood doing exactly what floods do. Checking one claim takes longer than making ten. Every unchecked claim feels like a point scored. And when checking is impossible, what decides? Confidence and jokes. You needed a pause button and fifteen minutes to do what the audience had two minutes to do live. This is the raw material of the Gish gallop — volume as smokescreen; a later session gives it its name and its CRITERIA. Caution if you preview the name: many claims alone is NOT a gallop — a dense policy answer can be many legitimate claims, and the wall shows the CHECKER’S experience, convicting neither debater. Refuting costs ~10x asserting (Brandolini’s law), so in a timed format every unanswered claim reads as a point scored, and volume is the dominant strategy for BOTH sides. Connections: it is WHY the double reframe went unnoticed (a flood of claims hides a dodged question), and it is Kahneman System 1 taking over when System 2 is flooded — they will read Kahneman for a later session; this is his thesis live on stage, early. Let the claim-wall fragment sit in silence for a few seconds before the count appears; the visual does the arguing. THE NUMBER SURVIVES CHECKING: the wall lists 20 checkable items over the 2:11 cut ≈ one per 6.5 seconds. If a student counts and challenges you, that IS the teaching moment — congratulate them for checking a claim about unchecked claims. NAME THE DOUBLE OPACITY, aloud: “sequestration,” “FDR,” “the Joint Chiefs” are foreign to this room — and that is the point, not a problem. American viewers couldn’t check these at speed either; feeling lost in the wall is the flood working on you, not a language gap. Say this explicitly, or some students will conclude they’re lost because it’s foreign. The three bullets are not just intuitions — each is a documented psychological finding; the next slide names the three, and the research itself belongs to a future session. BIG-PICTURE PREVIEW if wanted, one sentence (Zaller 1992): across decades of survey data, public attitudes track the RELATIVE intensity of competing message streams — what often decides is which stream is louder, not which is right. A later session harvests this properly (the misinformation and persuasion sessions).

Why Flooding Works?

Three reasons — each a documented psychological finding:

too fast to reject
too much to evaluate
too confident to dismiss

The research behind each — and the defense — comes in a future session.

Part 3: The Toolkit, Named

Standard Form: Why and How

Numbering the premises and stating the conclusion — standard form, or the Quick Logic Check written down:

one line per premise (including potential hidden premises)
conclusion at the end

P1.	The Navy has fewer ships than in 1917.
P2. (unspoken)	Fewer ships means insufficient capability.
C.	Don’t cut the military budget.

The Same Steps, on the Page

You found the debate’s premises — and its hidden premise — by ear.

We can also do the same with text to find:

premises
conclusion

“We regulate television advertising, we regulate campaign finance, and we regulate defamation. AI-generated political videos can deceive far more people far faster than any of these. It would be absurd to leave them as the one unregulated channel. Congress must act.”

The Reconstruction

P1.	We already regulate TV ads, campaign finance, and defamation.
P2.	AI political videos can deceive more people, faster, than any of those.
P3.	(implicit) Channels at least as harmful as regulated ones should also be regulated.
C.	Congress must regulate AI-generated political videos.

Notice P3, which was nowhere in the text - argument would not work without it

Typical arguments leave premises unstated: enthymeme.

Enthymemes

You already took two apart today:

“Our Navy is smaller than 1917 — I won’t cut the military budget.”
- hidden premise: fewer ships means insufficient capability
“We already regulate TV ads, campaign finance, and defamation — Congress must regulate AI”
- hidden premise: AI is as harmful as TV ads, campaign finance, and defamation

Hidden premises stay unstated because stating them invites scrutiny.

The Principle of Charity

When you reconstruct someone’s argument, you choose which hidden premise to attribute.

Charity says: attribute the strongest plausible one.

Reconstruct the argument its author would endorse, not the dumbest version you can refute.
Refuting the weak version wins nothing: the strong version is still standing.
Charity is also self-interest: you only learn something when you beat the best case against your view.

The limit: if no plausible premise can bridge the gap, say so — the argument fails.

NARRATION: One rule governs how you fill in hidden premises: charity. When you reconstruct someone’s argument, attribute the strongest plausible premise — the argument its author would actually endorse, not the dumbest version you can knock down. Refuting the weak version wins nothing; the strong version is still standing. And charity is self-interest: you only learn something when you beat the best case against your view. But charity has a limit. If no plausible premise can bridge the gap, say so — the argument fails. Your job is to make arguments fair, not good. DO NOT NAME THE FALLACY HERE. “Refuting the weak version” is the un-named preview of the straw man, which gets its name, its family, and its same-claim test in session 10 (fallacy 5 of 12). If a student supplies the name, confirm it and park it: “right — that one gets its name and a proper test later in the course.” Today it stays a rule about how YOU reconstruct, not a label for what THEY did. Procedure to say aloud (Vaughn, The Power of Critical Thinking 2019, pp. 76–77): write the premise that would make the argument airtight and that the author would accept; too strong to believe, weaken to plausible; still unbelievable, the argument fails. Vaughn’s canonical example (p. 73): “assault rifles should be banned — they can kill people” hides “everything that can kill people should be banned” — stated aloud, obviously false: the limit in action. Reconstruction-with-charity is what next session’s team activity grades.

Charity in the Debate

Romney gave two reasons. Obama answered one.

Romney: fewer ships than 1917 — and the Navy says it needs 313, it has 285.
Obama: “We also have fewer horses and bayonets.”

The version he answered: ship counts measure strength. One joke ends it.

The version left standing: the Navy’s own current requirement — 313 needed, 285 in the fleet.
- No cross-era count. Horses and bayonets never touch it.

That is the uncharitable move — and you already fixed it. The Step 8 repair was charity.

NARRATION: You do not need a new example for this — you spent an hour on one. Romney gave two reasons: the Navy is smaller than in 1917, and, separately, the Navy’s own assessment says it needs 313 ships and has 285. Obama answered the first: we also have fewer horses and bayonets. And that answer is devastating — against the counting premise. Now ask the charity question: was that the strongest version of Romney’s argument? No. The 313 figure is a current needs assessment; it already counts carriers and submarines, so no comparison across eras can answer it. The joke never touches it. Obama beat the version of Romney that was easiest to beat, and the strong version was still standing when the segment ended. That is the uncharitable move, and now it has a name. And here is the part to feel good about: you already fixed it. When you rewrote his reply in Step 8, the rule you were following was charity — both repaired arguments answer the strongest thing the other side said. That is what the repair was. This slide cashes the promise made at the top of Part 3: “charity — how you repaired the debate.” Point back at “What the Repair Changed”: “Both attack the STRONGEST version of the other side” IS the definition of charity, already on the board in their own words. BALANCE, say it aloud so this does not read as partisan: Romney is not the charitable one here either — Step 4 already showed his own hidden premise (a 1917 ship and a 2012 ship are the same unit), and the repair fixed BOTH sides. The charge is against the move, not the man; in a two-minute timed format, both sides reach for the weakest version of the other. PRECISION if a sharp student pushes: strictly, the charity rule governs hidden premises you ATTRIBUTE, and Romney stated the counting premise out loud — so this is the second bullet of the previous slide (“refuting the weak version wins nothing”), not the first. Concede the distinction, then note they travel together: Obama’s reconstruction treats the count as the load-bearing premise, which is precisely the choice charity constrains. If a student names the fallacy here, park it (see the note on the previous slide): the name arrives in session 10.

Exit Check (4 minutes, closed notes)

“Electric scooters should be banned from campus. Two students were injured last month, and the university is responsible for keeping students safe.”

Alone, on a slip of paper:

The conclusion.
The stated premises — one line each.
One plausible hidden premise.

NARRATION: Last task, and this one is yours alone — closed notes. Read the scooter argument. Write three things: the conclusion; the stated premises, one line each; and one plausible hidden premise. Pause the slides now and give it four honest minutes. This is the whole session in miniature — if you can do this on an argument you have never seen, today worked. The independent check the session otherwise lacks: fresh material, no scaffolding, closed notes. Collect the slips — they are your fastest read on who can do it alone, and the same skill the next session’s warm-up will retrieve. DEBRIEF once the slips are in, 60 seconds and spoken only: “So — is the weak spot a false premise, or the therefore?” That is where the weak-spot line in the key gets used. Keeping it oral rather than written is what keeps four tasks from eating a four-minute clock, and the room answers it together.

ANSWER KEY

Conclusion: scooters should be banned from campus.
P1 (stated): two students were injured last month.
P2 (stated): the university is responsible for keeping students safe.
Hidden premise: a ban is the appropriate response to those injuries.
Weak spot: the THEREFORE. Grant both premises and the causal claim — injuries + duty still don’t entail a BAN. Helmets, speed limits and bike lanes all satisfy the duty.

Also strong, if it comes up: poking P1’s base rate — two injuries out of how many riders? And the helper premises behind the hidden one: that scooters caused the injuries, and that two a month is a significant danger.

Credit: any well-argued verdict earns full marks. The skill being tested is locating the weakness, not matching this key.

What You Leave With: Two Moves

Practiced today on a live presidential debate:

Spot the argument — reasons for a disputed claim, or just noise?
Rebuild it — standard form, hidden premises said aloud, charitably.
- Then find the weak spot: a premise, or the therefore.
- And when it is worth it, repair it — the version they should have made.

Live speech comes too fast to check in real time — these two moves let you slow it down and check it.

NARRATION: Two moves are now yours. Spot the argument: reasons for a disputed claim, or just noise? And rebuild it: standard form, hidden premises said out loud, charitably — and then the part you just did on the scooter slip: point at the weak spot, a premise or the therefore. And when an argument is worth the effort, go one step further and repair it — build the version they should have made, the way you coached Obama’s reply. Live speech will always flood you — but the pause button is yours now. Next session, two more moves: sorting premises into kinds, and probing exactly where arguments break. Keep the toolkit warm — we open next time by reconstructing from memory. Close by pointing back at the Quick Logic Check from the start: same three questions, now trained on real material. The pause-button line calls back Step 7 — floods win live, standard form wins on paper. The teaser matters: the next session opens with a from-memory reconstruction, so tell them to keep the toolkit warm. End there; don’t add content after the teaser.