An objection arises: if someone is present today but absent tomorrow, does knowledge admit its contradiction? The response specifies the time and subject of the judgment.
“Zayd is present at this gathering today” and “Zayd is absent from it tomorrow” are not contradictory claims about the same time. Both can be true. The original report still needs valid grounds for its assertion about today.
Thus a change in the world must not be confused with a contradiction in knowledge. Contradiction requires fixing the subject, predicate, time, and relevant respect before comparing affirmation with denial.