لكن النهار ليس بموجود
But daytime is not present.
The previously accepted conditional states that sunrise entails daytime. The exceptive premise denies daytime, so the textbook concludes:
فالشمس ليست بطالعة
Therefore the sun has not risen.
The conclusion does not arise because “sun” and “day” have the same meaning. It follows from the connection asserted by the original conditional.
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Exceptive Syllogism: Valid Inferences from Connected and Disjunctive Conditionals
لكن النهار ليس بموجود
But daytime is not present.
The previously accepted conditional states that sunrise entails daytime. The exceptive premise denies daytime, so the textbook concludes:
فالشمس ليست بطالعة
Therefore the sun has not risen.
The conclusion does not arise because “sun” and “day” have the same meaning. It follows from the connection asserted by the original conditional.