Appearance versus reality. Who is truly virtuous, charitable, chaste, knowledgeable, just, etc. and who merely pretends to be and/or has the reputation of being so? Characters say one thing and mean another, or they act at variance with their speech. How, in Fielding's view, can the reader distinguish the person who pretends out of vanity or who is hypocritical from the truly good man/woman?
Abuse of power, by individuals, classes, institutions.
Inhumanity of individuals and society.
Lust versus chastity.
The nature of goodness. Fielding admired honesty, integrity, simplicity, and charity, believed that virtue is seen in an individual's actions, but recognized the difficulty of making moral judgments. How is the reader to judge the postilion who gave Joseph his coat but was later convicted of stealing chickens? or Betty, who is charitable and promiscuous? Nor do good men necessarily have harmonious relationships or understand each other, as is seen in Adam's interactions with the Catholic priest and the innkeeper previously hoodwinked by the "generous gentleman."
Charity. (This theme is related to the issue of faith versus works.)
Vanity. Are there degrees or kinds of vanity? The vanity of a Leonora is destructive, but what is the effect of Adams's vanity (his pride in his worldly knowledge derived from books, his pride in his sermons, and his pride in his excellence as a teacher)?
City living versus living in retirement in the country. This was a common theme in eighteenth century literature, as it had been in classical Roman literature. Wilson's story contrasts the useless, aimless, destructive life of London with the idyllic, simple pleasures of living in the country.