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Logic / Unit 9   Logic 433 worked example, 60 to 90 seconds

Full Reconstruction Walkthrough

Captions available

The idea

Reconstructing an argument means locating the conclusion, striking filler, standard-forming the premises, supplying any missing premise charitably, mapping the structure, and classifying the support on offer.

In practice

The paragraph: our schools are struggling, and frankly it is heartbreaking. Class sizes have grown by a third in five years. Teachers are leaving faster than we can hire. The council must fund the recruitment plan. Locate the conclusion — the council must fund the recruitment plan. Strike the filler. And frankly it is heartbreaking carries feeling and no support, so it goes, struck through but still visible: what the paragraph said, against what it argued. Standard-form the premises. Class sizes have grown by a third in five years. Teachers resign faster than replacements are hired. Supply the missing premise. Nothing connects staffing problems to this particular plan, so charity supplies the most reasonable version: the plan would address the shortfall. Map the structure. The two factual premises converge on the supplied one, and together they support the conclusion. Classify. Nothing claims necessity, so this is inductive and the question is strength. The supplied premise is the weak link, since no evidence is offered that the plan works.

Where people slip

Striking filler and striking a premise you find weak are different operations. Filler offers no support; a weak premise offers support you doubt. Removing the second tidies the argument into one the author never made.

Your place on the trail

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Unlocks

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