Premise:
"Far more convincing than Mr. Inglethorp's stony denials!" I could not help laughing. "
Hypothesis: I could not help myself from laughing.

yes

Premise:
"From now on, every Ser and Sather will protect you with the lower and the upper magic."
Hypothesis: Each Ser and Sather are bound by magic to protect you with it.

it is not possible to tell

Premise:
"The history does not explicitly address the possibility that the 20."
Hypothesis: The history does not address that.
yes