Delineate a speaker's argument and evaluate its reasoning, relevance and sufficiency

Learning goal: Listen to a speaker, delineate the argument into its overall claim, specific claims, evidence and reasoning, and evaluate the soundness of the reasoning and the relevance and sufficiency of the evidence. Identify the moments when irrelevant evidence is introduced, and explain why it is irrelevant even when it is true.

Original speech transcript — Remarks to the Cedar Hollow Student Council on the Lunch Period. The school, the speaker (an eighth grader named Dev) and every figure are invented. Read the transcript once for the shape of the argument; then have it read aloud while you take notes without looking.

"Thank you for hearing me. I am asking the council to recommend that our lunch period grow from 25 minutes to 35 minutes, starting next semester. I have three reasons.

"First, we do not have enough time to eat. For five school days in October I stood at the cafeteria door with a stopwatch and timed how long the last person in line waited to be served. The waits were 8, 11, 9, 10 and 7 minutes, an average of 9 minutes. Subtract 9 from 25 and the last students in line have 16 minutes to sit down, eat and clear their trays. The health teacher told our class that eating too fast is bad for digestion, and 16 minutes is fast.

"Second, a longer lunch would improve afternoon learning. My cousin goes to Milford Bend Middle School, where lunch is 40 minutes, and last year her school won the regional science fair. Also, I asked six friends at my table whether they would pay better attention in sixth period after a longer lunch, and all six said yes. Everyone knows that a hungry, rushed student cannot concentrate.

"Third, this change costs nothing. The cafeteria was repainted over the summer, and it looks wonderful, so the space is ready. The extra ten minutes could come from shortening each of our six class periods by two minutes, which no one would notice. Wait: six times two is twelve, so we would shorten five periods by two minutes. The schedule already changes for assemblies, so the office can change it.

"Some people will say the teachers need every minute. But our teachers are excellent. Last spring the eighth-grade team was named a district team of the year, and excellent teachers can make up two minutes.

"In short: the line data show that students have too little time to eat; a longer lunch will help us learn; and the cost is nothing. I ask the council to vote yes."

Delineate before you judge. To delineate an argument is to trace its parts and lay them out so that each can be examined on its own. Listening does not allow you to reread, so the layout has to be built from notes: an overall claim, the specific claims that support it, the evidence offered for each, and the reasoning that is supposed to connect evidence to claim. Dev's overall claim is that lunch should grow to 35 minutes. His three specific claims are that students lack time to eat, that a longer lunch would improve afternoon learning, and that the change costs nothing. He also answers one objection. Only after this map exists can you evaluate fairly; judging a speech from a single striking sentence is how listeners are misled in both directions.

Three tests, applied separately. Relevance asks whether a piece of evidence bears on the claim it is attached to. Sufficiency asks whether there is enough evidence, and evidence of the right kind, to support the claim's size. Soundness asks whether the reasoning that connects evidence to claim is valid and whether what it rests on is true. A piece of evidence can pass one test and fail another. The stopwatch data are relevant to the eating-time claim and the arithmetic is correct: 25 minus 9 is 16. But the arithmetic establishes only that, on those five days, the last student in line had on average 16 minutes left; the step from 16 minutes to "not enough time to eat" rests on "16 minutes is fast," which the speech asserts without any standard. Sufficiency is where the data are weakest. Five days in one month, timing only the last person in line, tells you about the worst case on those five days; it does not tell you how many students face it. That is a limit to state, not a reason to discard the data.

Recognizing irrelevant evidence. Irrelevant evidence is often true, pleasant and delivered with confidence, which is exactly why a listener must be able to name it. The repainted cafeteria is real in the story and looks wonderful, and it has no bearing on how many minutes anyone has to eat. The eighth-grade team's award is a genuine compliment; it is evidence for Dev's side claim that the teachers are excellent, but it says nothing about whether teachers need their minutes, which is the objection he is answering. Both are introduced at moments when the argument is thin, and each invites the audience to transfer a good feeling onto an unsupported claim. The test is simple: if this evidence were false, would the claim be any weaker? If not, the evidence is irrelevant.

Unsound reasoning and insufficient evidence. The cousin's school is relevant in the loose sense that it concerns lunch length and learning, but the reasoning is unsound: a science-fair win could have dozens of causes, one school is one case, and the speaker never shows that the longer lunch produced the win. Correlation is offered as cause. The six friends are relevant, but six self-selected people answering a leading question at one table cannot support a claim about the whole school; the evidence is insufficient. "Everyone knows" is not evidence at all; it asks the audience to supply the support the speaker has not found. The third claim contains a contradiction the speaker does not notice: taking ten minutes from class periods is a cost, so "costs nothing" rests on a false premise, and "no one would notice" is asserted without evidence. To his credit, Dev corrects his own arithmetic in mid-speech, six times two being twelve, and lands on five periods; the honest listener records the correction rather than the error.

A worked model of the full evaluation. Overall claim: extend lunch to 35 minutes. Claim one is relevantly supported by measured waits, with correct arithmetic, but its key step, that 16 minutes is too little, is asserted, and the sample is insufficient. Claim two is supported by one loosely relevant comparison treated as cause, one insufficient poll, and one appeal to common belief; it is unsupported as stated. Claim three rests on an irrelevant detail about paint and a premise that is false, since lost class time is a cost. The rebuttal introduces an award that supports only the side claim that the teachers are excellent. Conclusion: the argument's strongest part is its first claim, and a council that wanted to act on it would ask for wait times across a whole month and for the number of students affected. Notice that evaluating the argument as weak is not the same as concluding the proposal is bad. A weak argument for a proposal leaves the proposal unproven, not refuted, and a good council would say which evidence would settle it.

Worked delineation of claim one: Claim: students lack time to eat. Evidence: five timed waits of 8, 11, 9, 10 and 7 minutes, average 9; the health teacher's statement about digestion. Reasoning: 25 minus 9 leaves 16 minutes, which is "fast." Relevance: high, the data concern the lunch period directly. Sufficiency: limited, five days, one line, worst case only, and "16 minutes is fast" is asserted rather than supported by any standard. Soundness: the subtraction is valid, but the step from 16 minutes to "too little" is unsupported; the digestion point is second-hand and vague. Verdict: the best-supported claim in the speech, with stated limits.

Worked identification of irrelevant evidence: "The cafeteria was repainted over the summer, and it looks wonderful, so the space is ready." Apply the test: if the cafeteria had not been repainted, would the claim that a longer lunch costs nothing be any weaker? No. Appearance has no relationship to minutes. The word "so" makes it sound like reasoning, but it connects two things that do not bear on each other. Record it as irrelevant and move on; do not let the pleasant fact stand in for support.

Worked evaluation of the rebuttal: Objection anticipated: teachers need every minute. Response offered: the team won an award, and excellent teachers can make up two minutes. The award supports the side claim that the teachers are excellent, but it is irrelevant to whether minutes are needed. "Can make up two minutes" is a new claim with no evidence. A sound rebuttal would need something like a comparison of what is taught in a 45-minute period and a 43-minute one, or teachers' own statements about the loss. The rebuttal changes the subject from time to quality.

Argument map: While the transcript is read aloud, build a map with the overall claim at the top, the three specific claims beneath it, and under each claim its evidence and reasoning. After the reading, mark every piece of evidence with R for relevant or I for irrelevant, S for sufficient or N for not sufficient, and mark each piece of reasoning as sound or unsound with a one-phrase reason. Compare your map with a partner's and resolve any difference by returning to the transcript.

Independent performance: Listen to a second short original speech prepared by a classmate or teacher on a different proposal, containing at least one irrelevant piece of evidence and one unsound inference. Without a transcript, delineate the argument, evaluate each claim on the three tests, and identify the irrelevant evidence with the "would the claim be weaker" test. Then write a 200-word evaluation that names the strongest claim, the weakest, and the evidence that would be needed to settle the proposal. Success criteria: every specific claim is listed; every piece of evidence receives a relevance and a sufficiency judgment with a reason; every irrelevant item is identified and explained; the evaluation distinguishes a weak argument from a bad proposal.