age of reason

The age of reason is the point at which a child becomes capable of moral responsibility and rational thought—traditionally around seven years old in Catholic doctrine.

More broadly, it describes when someone becomes old enough to think independently: She reached the age of reason and started questioning everything.

Capitalized, the Age of Reason refers to the Enlightenment, the 17th- and 18th-century intellectual movement emphasizing rationality over tradition and superstition.