Presumptive
Part of speech: adjective
Definition: based on presumption, probability, conjecture, hypothesis or belief making presumptions; behaving as one who presumes, who assumes that which they perhaps shouldn't.
Credible
Part of speech: adjective
Definition: believable or plausibleauthentic or convincing
Example sentence: The logical man must either deny all miracles or none, and our American Indian myths and hero stories are perhaps, in themselves, quite as credible as those of the Hebrews of old.