The innī example can be arranged as follows:
Minor premise: Zayd has a fever.
Major premise: According to the historical theory assumed in the textbook, every feverish person has corrupted humors.
Conclusion: Zayd has corrupted humors.
“Fever” is the ground on which the conclusion is inferred, yet within the same theory it is not the real cause of the alleged corruption.
Logical entailment still depends on accepting the major premise. A fever does not diagnose “corrupted humors” in modern medicine.