Lesson 4 — Hidden Assumptions: Reading the Unsaid

Summary

Learners learn to critique a moral argument by finding its hidden assumptions and bias — the part that is said without being said. Using an iceberg image, they separate a stated claim from its unstated premises, test those premises, and name where bias slips in.

Objectives

• Critique a moral argument for hidden assumptions or bias, by separating its stated claim from its unstated premises. (D09.S1.10.02)

Connection

Every argument is like an iceberg: only a little of it is above the water. Above the water is what the speaker says out loud — “this phone is good for everyone.” Below the water is what the speaker assumes without saying it — that everyone can afford a phone, that everyone has a network, that “good” is measured the same way for everyone. An argument can look complete and still rest on parts no one ever said out loud. Finding those parts — and asking whether they are true and whether they are fair — is the heart of reading an argument critically. It is a skill you can use on an advertisement, a speech, a news report, or your own reasoning.

Materials

• Argument iceberg sheet
• Two short moral arguments

Preparation

• Copy the iceberg sheet and the two arguments.
• Retrieval: from Grade 9, recall the difference between a fact, a belief, and a value; and that a moral argument has premises and a conclusion. Today we look for the unstated premises.
• Prepare one worked example of finding a hidden assumption.

Facilitator note

This lesson is written to the learner (“you”). The idea to land: an argument’s visible part is small; its hidden assumptions and bias are the part below the water — find them, test them, and the argument is no longer invisible. Teach the skill with a worked example, then guided practice (S-011). Frame critique as care, not attack: we read an argument closely to understand it better, and to notice who is left out. The critical-thinking lens is the spine: ask “what must be true for this to be true, and is it?” The egalitarian lens: bias often hides in the question of who is assumed to matter — “everyone” can silently mean “people like the speaker.” The global lens: arguments are shaped by where they are made; an assumption that is obvious in one place is strange in another, and that difference is information, not a mistake. Keep questions open (philosophy §11) and distinguish evidence from values (philosophy §5): finding an assumption is a claim about what the argument says; judging whether that assumption is fair is a question of values. Preview: next lesson we rebuild the argument with the assumptions brought into the light.

Procedure

1. Recall (5 min). From Grade 9: what is the difference between a premise and a conclusion? Give a one-sentence example.
2. Meet the iceberg (10 min). Look at the iceberg sheet. Above the water: the stated claim. Below the water: the hidden assumptions — the things that must be true for the claim to hold. Read one short argument together and mark where the waterline is.
3. Worked example (10 min). Watch one critique done step by step for “Everyone should switch to smartphones; they make life better for all of us.” (a) What is said? (b) What is assumed? — that everyone can afford one; that everyone has a network and the skills to use it; that “better” is the same for everyone. (c) Test each assumption: is it true for everyone? (d) Where does bias slip in? — the argument speaks for “all of us” while assuming a life like the speaker’s.
4. Guided practice (15 min). In a pair, take the second argument and repeat the four moves. Write down at least two assumptions, then test each one. Swap and compare what you found.
5. Independent practice (10 min). In your journal, choose one argument and write: the stated claim, two hidden assumptions, and where bias slipped in. Mark “not yet” and retry if you only found one.
6. Close (5 min). Share one hidden assumption you found. Notice how the same sentence looked different once the waterline was drawn.

Differentiation

• Support: Provide a half-filled iceberg (claim written, one assumption already placed) to complete.
• Extension: Find a counterexample — one real person or place where the assumption fails — and say how it changes the argument.
• Expression: Learners who do not speak aloud can write the claim and assumptions on the iceberg, point to the hidden parts, or have a partner read their written critique — no step requires the voice.

Assessment

• Formative (peer + self): Can the learner separate a stated claim from its hidden assumptions, test one assumption, and name where bias slips in?
• Portfolio artifact (unit): The completed iceberg, kept as the first page of the “critique” section of the portfolio.

Home connection

Find a claim in an advertisement or a headline at home. Ask: what must be true for this to be true? Name one assumption together.

Resources

• On worked examples and guided practice: Kirschner, Sweller & Clark (2006), https://doi.org/10.1207/s15326985ep4102_1 (S-011).
• On asking “who made this and why” about any message: NAMLE, “Key Questions to Ask When Analyzing Media Messages,” https://namle.org/resources/key-questions/ (S-151).