words are Ælflæd of Duckford's unless specified otherwise, or unless clearly dictionary quotations
Probity is integrity, but more. Probity is honesty, but in a form more related to trustworthiness. When a person has probity, it is easy for others to trust his words and to have faith in his judgment.
Buddha said [or someone said]:
Do not believe in anything simply because you have heard it. Do not believe in traditions because they have been handed down for many generations. Do not believe in anything because it is spoken and rumored by many. Do not believe in anything simply because it is found written in your religious books. Do not believe in anything merely on the authority of your teachers and elders. But after observation and analysis, when you find that anything agrees with reason, and is conducive to the good and benefit of one and all, then accept it and live up to it.
Still, nice whoever said/wrote it.
The "live up to it" is the hardest of all. When you find that another person *is* worthy of trust and you have discovered that on your own by your own observation and test, THEN the person has probity with you. Don't take anyone's word for the probity of another.
From Webster's Revised Unabridged Dictionary (1913) [web1913]:
Probity (from French probité, from Latin probitas, from probus: “good, honest”):
Complete and confirmed integrity; uprightness (synonyms at “honesty”) (American Heritage Dictionary) That's the definition used by Word of the Day when they featured "probity."
Virtue or integrity tested and confirmed; strict honesty (synonyms under “virtue) (Funk & Wagnall)
Moral excellence, integrity, rectitude, uprightness, conscientiousness, honesty, sincerity (Oxford English Dictionary)