Salb al-ʿumūm denies that a predicate applies universally.
لَمْ يَقُمْ كُلُّ إِنْسَانٍ
It was not the case that every person stood.
The statement is true if nine out of ten stood and one did not. It can also be true if nobody stood, since universal standing is still false. Only in the first scenario is the standing of some people additionally established.
Hence denial of universality is not equivalent to asserting that some definitely stood.
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Fronting, Kull and Negation: Denial of Universality versus Universal Denial
Salb al-ʿumūm denies that a predicate applies universally.
لَمْ يَقُمْ كُلُّ إِنْسَانٍ
It was not the case that every person stood.
The statement is true if nine out of ten stood and one did not. It can also be true if nobody stood, since universal standing is still false. Only in the first scenario is the standing of some people additionally established.
Hence denial of universality is not equivalent to asserting that some definitely stood.