ST Suppl., q. 21
Of the Definition, Congruity and Cause of Excommunication
Supplement — compiled posthumously from Aquinas's early Sentences commentary
We must now treat of excommunication: we shall consider: (1) the definition, congruity and cause of excommunication; (2) who has the power to excommunicate; (3) communication with excommunicated persons; (4) absolution from excommunication.
Under the first head there are four points of inquiry:
(1) Whether excommunication is suitably defined?
(2) Whether the Church should excommunicate anyone?
(3) Whether anyone should be excommunicated for inflicting temporal harm?
(4) Whether an excommunication unjustly pronounced has any effect?