Here is a premise:
On the other hand, Mrs. Cavendish believed that the slip of paper to which her mother-in-law clung so tenaciously was a written proof of her own husband's infidelity.

Here is a hypothesis:
Mrs. Cavendish's mother-in-law had been holding on to a slip of paper.

Is it possible to conclude that if the premise is true, then so is the hypothesis?
yes