Unit 8 · Detecting Reasoning Errors
Emu Egg — False Uniqueness & "Up To" Misread
Lesson 5 of 10
About this lesson
Charlotte makes the "false uniqueness" error — matching two traits doesn’t prove the egg MUST be an emu’s. Oliver misreads "up to 13 cm" as a MINIMUM — but it’s a maximum. A 10 cm emu egg is perfectly valid. Both are wrong.
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Question
Facts: An emu’s egg is dark green, speckled with white spots, and can measure up to 13 cm long. Only an ostrich’s egg is larger.
Charlotte says: "This egg is dark green, and fairly large, so it must be an emu’s."
Oliver says: "But it’s only about 10 cm long, so it can’t be!"
If the information in the box is true, whose reasoning is correct?
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