The Phone Ban and the Falling Mathematics Scores
At a provincial secondary school, the debate club must advise the principal on a proposed ban on mobile phones during school hours. In 2022 the school allowed phones in senior classes. Since then, the average score in the end-of-term mathematics examination has fallen from 64% to 56%. Teachers report more classroom interruptions, and a parent survey shows 70% support a ban. One student argues: Phones must be causing the drop. If we ban them, marks will return to 64%. Another replies that the school also changed the mathematics syllabus and lost two experienced teachers in the same year. The principal wants a decision within one week and can enforce a ban immediately, but has no budget for a controlled study. The debate club is asked to judge whether the student’s argument is strong enough to justify the ban.
1. Reconstruct the student’s argument in premise-conclusion form and identify the main inferential error. What further evidence would make the causal claim credible?
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Reconstruction: (P1) Phones were allowed in 2022. (P2) Mathematics scores fell from 64% to 56% afterwards. (P3) Teachers report more interruptions. (C1) Phones caused the score drop. (C2) A ban will restore 64%. Error: The argument moves from temporal succession and correlation to causation (post hoc ergo propter hoc) while ignoring confounders named in the setup: the syllabus change and the loss of two teachers. Parent support is irrelevant to the causal claim. What would help: a comparison between classes or schools with and without phones, controlling for syllabus and teacher experience; a plausible mechanism with dose-response evidence; timing data showing interruptions rose before scores fell; and a trial ban with before-and-after measurement. Even a demonstrated causal link would not by itself prove that a ban restores the old average, because the 64% baseline depended on other conditions. The conclusion should be probabilistic and modest.
2. The principal says: Even if we cannot prove phones caused the fall, a ban is justified because 70% of parents support it and teachers report disruption. Assess this appeal using at least one concept from critical reasoning, such as appeal to popularity, precautionary reasoning, or burden of proof.
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Assessment: The principal’s argument is a mixture. The 70% survey is evidence of preference, not of causation or educational harm; treating it as decisive is an appeal to popularity. Teacher reports are relevant but anecdotal and may be biased by expectation. Precautionary reasoning: Where children’s learning is plausibly harmed and a ban is reversible, a temporary, monitored restriction can be justified without conclusive causal proof, provided the burden is proportionate and evidence is reviewed. Burden of proof: The student’s strong causal claim bears the burden, not the sceptic. Decision: A blanket permanent ban on the basis stated would be weakly justified; a trial ban limited to lessons, with interruption logs and score monitoring, is defensible. The principal should announce criteria for ending or extending it. This respects uncertainty without making majority preference the sole foundation of policy.