 For war to be morally permissible, is it necessary that, in addition to having a just cause, it is also certain that the just cause will be achieved? The Renaissance Thomist commentator, Cardinal Thomas de Vio, known as Cajetan, thought  so.[18]  Suárez considered such absolute certainty to be unachievable, and requiring it to be undesirable: waiting to attain this degree of certainty could result in a dangerous postponement of the business of justice. In addition, he thought that this requirement discriminated against weaker countries by making it more difficult for them to pursue justice as compared to stronger countries (DDB 4.10).