The theory that some human actions, though conscious and deliberate, are morally indifferent, that is, neither good nor bad. Defended by Duns Scotus (c. 1264-1308) and his followers, it is not commonly held by Catholic moralists. Following St. Thomas Aquinas, they admit that in the abstract a human act can be morally indifferent, but not when considered individually in the concrete. Consequently, every deliberate act performed by a definite individual is always either morally good or bad.
The controversy revolves around the question: must every human action be explicitly directed to a morally good purpose? St. Thomas answers that an implicit intention to do what is right is sufficient for a morally good action, provided it is done with some reflection and exercise of freedom.